ENGLISH FOR AIRCONDITIONING AND HEATING
Edwin Molina Lascar English Teacher
DESCRIPCIÓN DEL CURSO En idioma ingles se ha posicionado como una de las lenguas mas habladas alrededor del mundo y con el cual muchos aspectos de la vida se desarrollan. En nuestros trabajos y oficios se ve cada día más la necesidad de aprender dicha lengua y hoy por hoy se constituye como una necesidad y una herramienta que nos impulsa a desarrollarnos y superarnos en nuestros trabajos. El presente curso esta dirigido a trabajadores y estudiantes de refrigeración los cuales poseen un nivel básico en la lengua inglesa y que por su necesidad requieren de un programa adaptado a su campo laboral. El curso tiene una intensidad horaria de 40 hrs durante diez sesiones por un periodo total de 2 meses y medio con una frecuencia de 4 hrs por sesión.
OBJETIVOS GENERALES Los estudiantes serán capaces de: 1. Comprensión al leer e interpretar textossencillos relacionados con su campo laboral. 2. Describir en forma sencilla situaciones, problemas y procesos. 3. Interpretar manuales informativos e instructivos reconociendo los elementos gramaticales y el vocabulario técnico referente a su área laboral.
OBJETIVOS ESPECÍFICOS El alumno será capaz de: 1. Seguir instrucciones sencillas. 2. Responder y formular preguntas en inglés a nivel básico. 3. Comprensión e interpretación de textos. 4. Responder en forma oral y por escrito a preguntas sobre un texto sencillo escrito en ingles. 5. Utilizar estructuras gramaticales y ortografía adecuadas. 6. Comunicar situaciones, necesidades y experiencias utilizando un vocabulario adecuado.
METODOLOGÍA Las clases serán principalmente presenciales y participativas. El profesor tendrá un rol rol de modelo y facilitador. Se creará un clima clima de confianza y creatividad donde los alumnos podrán participar activamente en situaciones de aprendizaje 2
DESCRIPCIÓN DEL CURSO En idioma ingles se ha posicionado como una de las lenguas mas habladas alrededor del mundo y con el cual muchos aspectos de la vida se desarrollan. En nuestros trabajos y oficios se ve cada día más la necesidad de aprender dicha lengua y hoy por hoy se constituye como una necesidad y una herramienta que nos impulsa a desarrollarnos y superarnos en nuestros trabajos. El presente curso esta dirigido a trabajadores y estudiantes de refrigeración los cuales poseen un nivel básico en la lengua inglesa y que por su necesidad requieren de un programa adaptado a su campo laboral. El curso tiene una intensidad horaria de 40 hrs durante diez sesiones por un periodo total de 2 meses y medio con una frecuencia de 4 hrs por sesión.
OBJETIVOS GENERALES Los estudiantes serán capaces de: 1. Comprensión al leer e interpretar textossencillos relacionados con su campo laboral. 2. Describir en forma sencilla situaciones, problemas y procesos. 3. Interpretar manuales informativos e instructivos reconociendo los elementos gramaticales y el vocabulario técnico referente a su área laboral.
OBJETIVOS ESPECÍFICOS El alumno será capaz de: 1. Seguir instrucciones sencillas. 2. Responder y formular preguntas en inglés a nivel básico. 3. Comprensión e interpretación de textos. 4. Responder en forma oral y por escrito a preguntas sobre un texto sencillo escrito en ingles. 5. Utilizar estructuras gramaticales y ortografía adecuadas. 6. Comunicar situaciones, necesidades y experiencias utilizando un vocabulario adecuado.
METODOLOGÍA Las clases serán principalmente presenciales y participativas. El profesor tendrá un rol rol de modelo y facilitador. Se creará un clima clima de confianza y creatividad donde los alumnos podrán participar activamente en situaciones de aprendizaje 2
diseñadas para la práctica del idioma en un contexto real.El desarrollo de los contenidos
temáticos
incluye
contenidos
gramaticales,
ortografía
y
pronunciación.Se utilizaran videos, diapositivas y lecturas para apoyar el logro de las habilidades.
EVALUACIÓN El logro de los objetivos de producción y comprensión será evaluado a través de todo el proceso de enseñanza
– aprendizaje y las evaluaciones serán
principalmente escritas. Ƀ PRIMER TEST = 25 % Ƀ SEGUNDO TEST= 25%Ƀ FINAL TEST= 40 %
REQUISITOS Asistencia a clases.
Asistencia a evaluaciones.
El alumno deberá presentar la totalidad de los exámenes y aprobarlos con 75% o mas y cumplir por lo menos con el 75% de asistencia para aprobar el curso.
CONTENT Present tense + - ? Verb to be
Motor, loads, Solenoid
Introduction:
Central Hydronic Air Conditioning
Air conditioning types of Air Conditioning systems Nouns – plural The article –the, a, an, some Refrigeration cycle
Systems English Grammar – Part of Speech Psychrometrics English Grammar – Verbs
Description of the refrigeration
Tools and Equipment
The adjective
Numbers and Spelling (Numerical
Selecting the refrigerant
Applications)
Refrigerant cylinder color codes
asking For Help, Directions.
Prefix - Suffix Loads Motors
Signal lights Health & Safety and Machinery Contactors and relays English grammar – Adjective Color, Shapes, Sizes and Materials 3
Magnetic Starter (Switch)
actuators
English Grammar - Present and
Comparative and superlative
Present continuous
Adjective
Tables measure and conversion
Heating System Symbols and Codes
English Grammar – Adverbs
Conjunction
Schematic Diagram
Refrigeration System
English grammar – past- past continuous
Modal verbs
Describing Systems
Objective pronouns
English Grammar – Preposition
Present - past Perfect continuous
Water System Centrifugal pumps English Grammar – Future and future continuous Water control valves and valves
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Simple Present Tense Structure To form the Present Simple Tense we use the verb's base form (go, work, speak, study). In 3rd person singular (he, she, it), the base form of the verb takes -s/es. (Auxiliary verbs "be," "do," "have", which can also be used as main verbs, are exceptions.) Affirmative form I, you work we , they he/she/it
works /-s/
go - goes / -es / watch - watches / -es / play - plays / -s / study - studies / -es / !Remember: to beI/you/we/they are he/she/it is
to doI/you/we/they do he/she/it does to haveI/you/we/they have he/she/it has Negative form I you DO NOT /don't/ we WORK they he/she/it DOES NOT /doesn't / WORK 1. She doesn't often go to the cinema. 2. I don't get up early at the weekend. 3. They don't speak English very well. Interrogative form I DO you WORK? we they DOES he/she/it
Examples 1. Philip gets up at 6 o'clock every morning. 2. I go to school every day. 3. She sometimesgoes out on Friday night. 4. I usuallysleep late on Sunday morning. 5. Peter works for 8 hours every day. 6. We usuallystart work at 8 o'clock. 7. My children oftenwatch TV in the afternoon. 8. He alwaysforgets his keys.
Use the Present Simple Tense:
when we talk about things that happen repeatedly or habitually With Present Simple Tense we often use time expressions such as always, often, sometimes, usually, seldom, on Saturdays, rarely, never , every day, etc.
1. I work in a bank. 2. Kate speaks English very well. 3. Tom lives in London.
when we talk about permanent or long-lasting situations
1. People make choices because they can't have everything they want. 2. Nurses work in clinics and hospitals. 3. Football is a very popular sport in Bulgaria.
when we talk about people or things in general
1. The Earth is spherical. 2. My birthday is in May. 3. California is in the Unated States. 4. The sun rises in the east. 5. Water freezes at 0°C (32°F).
to indicate general truths, facts and scientific laws
1. We arrive in Rome at 6 p.m. 2. The train leaves in five minutes. 3. The course starts next Thursday.
when we talk about travel plans and timetables (mainly with verbs such as go, leave, arrive, start, come, return etc.)
1. She loves jazz music. 2. My aunt hates travelling by train. 3. I like ice cream. I don't like spinach. 4. I think she is a wonderful person. 5. Do you believe in God? 6. I have no money at the moment. 7. My brother has a new car. 8. That bicycle belongs to me.
with state (or stative) verbs such as like, dislike, love, think, seem, look, know, feel, understand, want, need, hate, remember, forget, prefer, believe, mean, taste, hear, see, have(when the meaning is "possess"), own, belong, etc. These verbs are not normally used in the Continuous Tense (but there are exceptions).
1. Pour all ingredients into a mixing bowl and mix until smooth. 2. Walk down the street to the corner and then turn right.
to give instructions/directions
WORK?
1. Do they speak foreign languages? 2. Do you want a banana? 3. Does your sister play the piano? Questions and short answers: Do you like spaghetti? Yes, I do. No, I don't. Does she know Bulgarian? Yes, she does. No, she doesn't.
The Present Simple Tense is also used in : sentences after"when", "after", "while", "till" / "until", "before", "as soon as" - When the rain stops, we'll go out.I'll call you back as soon as I return home. zero conditional sentences (when the result of the condition is always true) - If you heat water to 100°C (212°F), it boils. first conditional sentences(Often called the "real" conditional because it is used for real (or possible) situations. These situations take place if a certain condition is met.) - If you finish your homework I'll bring you to the zoo.
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Notes about formation of the 3rd person singular (he, she, it): If the verb ends in consonant + y change y to i and add -es: study - studies, copy - copies, try - tries, carry - carries
If the verb ends in -ss, -sh, -ch, -x or -o, add -es to the base form: kiss - kisses, finish - finishes, watch - watches, mix - mixes, go - goes
Chose the correct
5. We ____________ to school every day.
form of the verb to be - am/is/are. 6. I ____________ walk to school every day. 1.It ___ cold today.
7. You don’t ____________ to school every day.
2. I ___ at home now.
8. He/She/It ____________ walk to school
3. They ___ Korean.
every day.
4. There ___ a pen on the desk.
9. They ____________walk to school every day.
5. My name ___ Nikita.
10. We don’t ____________ to school every
6. We ___ from Ukraine.
day.
7. That ___ right. 8. I ___ OK, thanks. 9. Clara and Steve ___ married.
11. Do I ____________ to school every day?
10. She ___ an English teacher.
12. ____________ you walk to school every day?
The following sentences express possession,
13. Does he/she/it ____________ to school
senses, emotions or mental activity. Verbs of
every day?
possession, senses, emotions and mental
14. ____________ they walk to school every
activity must be used with the simple present.
day? 15. Do we ____________ to school every day?
Put the verbs into the correct form. 16. Yes, I ____________. 17. No, 1.
I (like) _____ pizza.
I_______________.
2.
He (hate) _____ garlic.
18. Yes, you ____________. 19. No, you
3.
My sister (prefer)______ tea to coffee.
____________.
4.
I (want)_______ to get away from here.
20. Yes, he/she/it ____________. 21. No,
5.
She (not / understand)______ me.
he/she/it ____________.
6.
I (not / believe)_____ it.
22. Yes, we ____________. 23. No, we
7.
I (not / know)_____ why you are so
____________.
mean.
24. Yes, they ____________. 25. No, they
We (not / think)_____ that this is
____________.
8.
right. 9.
What (mean / it)_____?
10. (you / hear)____ the music?
26. When do you ___________ to school every day? 27. Why do ___________ walk to school every day? 28. Where ___________ she go to school every
Fill in the blank with the correct form of the verb OR the correct ―helping‖ verb.
day? 29. How does ___________ get to school every day?
1. I ____________ to school every day.
30. What ___________ they do in school every
2. You ____________ to school every day.
day?
3. He/She/It ____________ to school every day. 4. They ____________ to school every day.
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1. I _____ (read) a very interesting book now.
16. Let's change the conversation. It
2. Joanne ______ (work) eight hours a day.
_______(get) too serious.
3. Tonight we _____ (see) a play at the
17. Leap year _______(come) every four years.
thereatre.
18. My grandfather _______(grow) tomatoes in
4. Who ______ you _____ (speak) to just now?
his garden this summer.
5. I ________ (not know) him very well.
19. He ______(grow) them every summer.
6. What will you do if she _______ (come)
20. The children _________(leave) for school
late?
right now.
7. My wife ________ (like) coffee for breakfast.
21. The children ________(leave) at 8:30 every
8. What _____ Tom usually ______(have) for
morning of the week.
breakfast?
22. Shu! The baby _______(take) her nap.
9. Your train ______ (leave) at 17.25 from
23. In the north the season _________(change)
platform 3.
four times a year .
10. What ______ Mary _____ (do) ? She's a
24. Unfortunately, the patient ______ (die).
student.
25. The monsoon ______(come) once or twice
11. My whole family _______(go) to church
a year.
once a week.
26. It's spring and the days _____(get) longer.
12. My wife and I ______(go) to the beach in
27. The weather _____(get) very cold in
the summer.
Moscow in the winter.
13. Listen! The phone _____(ring) in the other
28. It _______(rain) hard, and I don't have an
room.
umbrella.
14. Rain seldom ______(fall) in the Sahara.
29. It's November and the birds _____(fly)
15. He is thirteen years old now, and his voice
south.
________(change).
. John___ (get up) at 7.00 and ___ (go) into the bathroom to wash. He___ (wash) his face and___(brush) his teeth. Then he___ (put on) his clothes. John's mother and father___ (have) coffee in the morning, but John ___(drink) orange juice to drink. At 7.45, John ___ (leave) his house and ___(walk) to the bus-stop. He___ (try) not to be late
Introduction Air-Conditioning Air-conditioning is a process that simultaneously conditions air; distributes it combined with the outdoorair to the conditioned space; and at the same time controls and maintains the required space’s temperature,humidity, air movement, air cleanliness, sound level, and pressure differential within predeterminedlimits for the health and comfort of the occupants, for product processing, or both. The acronym HVAC&R stands for heating, ventilating, air-conditioning, and refrigerating. The combinationof these processes is equivalent to the functions performed by air-conditioning.Because I-P units are widely used in the HVAC&R industry in the U.S., I-P units are used in thischapter. A table for converting I-P units to SI units is available in Appendix X of this handbook. Air-Conditioning Systems An air-conditioning or HVAC&R system consists of components and equipment arranged in sequentialorder to heat or cool, humidify or dehumidify, clean and purify, attenuate objectionable equipment noise,transport the conditioned outdoor air and recirculate air to the conditioned space, and control and maintainan indoor or enclosed environment at optimum energy use. The types of buildings which the air-conditioning system serves can be classified as: • Institutional buildings, such as hospitals and nursing homes • Commercial buildings, such as offices, stores, and shopping centers • Residential buildings, including single -family and multifamily low-rise buildings of three or fewerstories above grade • Manufacturing buildings, which manufacture and store products . Types of Air-Conditioning Systems
7
In institutional, commercial, and residential buildings, air-conditioning systems are mainly for theoccupants’ health and comfort. They are often called comfort air-conditioning systems. In manufacturingbuildings, air-conditioning systems are provided for product processing, or for the health and comfortof workers as well as processing, and are called processing air-conditioning systems.Based on their size, construction, and operating characteristics, air-conditioning systems can beclassified as the following. Individual Room or Individual Systems. An individual air-conditioning system normally employseither a single, selfcontained, packaged room air conditioner (installed in a window or through a wall)or separate indoor and outdoor units to serve an individual room, as shown in Figure 9.1.1. “Selfcontained, packaged” means factory assembled in one package and ready for use.
FIGURE 9.1.1 An individual room air-conditioning system
Space-Conditioning Systems or Space Systems. These systems have their air-conditioning — cooling,heating, and filtration — performed predominantly in or above the conditioned space, as shown in Figure9.1.2. Outdoor air is supplied by a separate outdoor ventilation system. Unitary Packaged Systems or Packaged Systems. These systems are installed with either a single selfcontained,factory-assembled packaged unit (PU) or two split units: an indoor air handler, normally withductwork, and an outdoor condensing unit with refrigeration compressor(s) and condenser, as shown inFigure 9.1.3. In a packaged system, air is cooled mainly by direct expans ion of refrigerant in coils calledDX coils and heated by gas furnace, electric heating, or a heat pump effect, which is the reverse of arefrigeration cycle. Central Hydronic or Central Systems.A central system uses chilled water or hot water from a central plant to cool and heat the air at the coils in an air h andling unit (AHU) as shown inFigure 9.1.4. Forenergy transport, the heat capacity of water is about 3 400 times greater than that of air. Central systemsare built-up systems assembled and installed on the site.Packaged systems are comprised of only air system, refrigeration, heating, and control systems. Bothcentral and space-conditioning systems consist of the following. Air Systems.An air system is also called an air handling system or the air side of an air -conditioningor HVAC&R system. Its function is to condition the air, distribute it, and control the indoor environmentaccording to requirements. The primary equipment in an air system is an AHU or air handler; both ofthese include fan, coils, filters, dampers, humidifiers (optional), supply and return ductwork, supplyoutlets and return inlets, and controls. Water Systems. These systems include chilled water, hot water, and condenser water systems. A water system consists of pumps, piping work, and accessories. The water system is sometimes called the water side of a central or spaceconditioning system. Central Plant Refrigeration and Heating Systems . The refrigeration system in the central plant of a central system is usually in the form of a chiller package with an outdoor condensing unit. Therefrigeration system is also called the refrigeration side of a central system. A boiler and accessories make up the heating system in a central plant for a central system, and a direct-fired gas furnace is often the heating system in the air handler of a rooftop packaged system. Control Systems. Control systems usually consist of sensors, a microprocessor-based direct digitalcontroller (DDC), a control device, control elements, personal computer (PC), and communicationnetwork. Based on Commercial Buildings Characteristics 1992, Energy Information Administration (EIA) ofthe Department of Energy of United States in 1992, for commercial buildings having a total floor area of 67,876 million ft2, of which 57,041 million ft2 or 84% is cooled and 61,996 million ft2 or 91% is heated, the air-conditioning systems for cooling include: Individual systems 19,239 million ft2 (25%) Packaged systems 34,753 million ft2 (49%) Central systems 14,048 million ft2 (26%) Space-conditioning systems are included in central systems. Part of the cooled floor area has been counted for both individual and packaged systems. The sum of the floor areas for these three systems therefore exceeds the total cooled area of 57,041 million ft2.
8
QUESTIONS:
1. The acronym HVAC&R stands for:
b. Heating Systems
a. Heating, Ventilating, Air-Conditioning, and
c. Mechanical Systems
Refrigerating. b. Hot, Ventilating, Air-Condensing, and
4. The acronym DDC stands for: a. direct digital controller (DDC)
Refrigerating. c. Heating, Ventilating, Air and Refrigeration
b. direct department controller(DDC) c. direct duct controller (DDC)
System. 2. The types of buildings which the airconditioning system serves can be classified as: a. Institutional buildings, shopping centers, Institutional
buildings,
normally employs either a single, selfcontained, packaged room air conditioner. a.Water Systems
ships and vehicles b.
5. The individual air-conditioning system
buildings,
Commercial
Residential
buildings,
b.Central Systems c. Individual Systems
Manufacturing buildings c.
Government
buildings,
Commercial
buildings, Houses, Manufacturing buildings
6. These systems have their air-conditioning — cooling, heating and filtration—performed predominantly in or above the conditioned
3. The following is not a Type of Air-
space.
Conditioning Systems:
a.Space Systems
a. Individual Systems
b. Heating Systems c.Control Systems
Nouns also denote abstract and intangible concepts. For example:
NOUNSA noun is a word used to re fer to people, animals, objects, substances, states,
BirthhappinessEvolutiontechnology.
events and feelings. Nouns can be a subject or an object of a verb, can be modified by an
We are going to explain some
adjective and can take an article or
rules that will help you to form the plural
determiner. For example:
forms of the nouns. The general rule is to add "-s" to the noun in singular. For exaample:
The
A white
9
Book – Book House – House Chair -
the noun already has an -s ending to mark
Chair
the plural, then the genitive marker appears only as an apostrophe after the plural form.For example:
When the singular noun ends in: we form their plural form by adding "-es". For exaample:
sandwi
–sándwich
bu – bus
potat - potato
bru
my girlfriend
brotherJohn
house
The Browns houseThe boys pens
- brush The genitive marker should not be confused
bo - box
with the " John
" form of contracted verbs, as in
a good student = John
a good
student.
When the singular noun ends in "y", we change the "y" for "i" and then add "-es" to
Many common nouns, like
form the plural form. But do not change the "y" for "ies" to form the plural when the
"engineer" or "teacher", can refer to men or
singular noun ends in "y" preceded by a
women. Once, many English nouns would
vowel. For example:
change form depending on their gender. For example: A man was called an "author" while
napp – napp
d
– da
t
a woman was called an "authoress". For
- to
example: However, there are many which do not form the plural in this way: For
exaample:
David Garrick was a very prominent eighteenth-century
Woman – WomenChild - Children
Sheep - Sheep
Sarah Siddons was at the height of her career as an
. in the 1780s.
The manager was trying to write a want ad, but he couldn't decide whether he
Nouns may take an " "
was advertising for a "
" ("apostrophe s") or
" to indicate
"
. If
" or a
"
Activity1: Circle the nouns and cross the rest words in the next list.
Compressor heart
When from
system
refrigerate pressure
discharges
temperature degrees water cycle capacity evaporator machine evaporation
design flow
heat
into
airdots refrigerant represent Vapor will Most diagram freezer
refrigerator
above
happy
Activity 2: Use the nouns to complete the following text on the next page.
10
is the _____1____.It takes refrigerant vapor in from the low __2___ side of the circuit, and discharges it at a much higher pressure into the high pressure side of the circuit. The compressor is the ___3__ of the system; it keeps the refrigerant flowing through the ___4___ at specific rates of flow, and at specific pressures. The rate of flow through the system will depend on the size of the unit,And the operating pressures will depend on the ____5_____ being used and the desired evaporator temperature. in this refrigeration cycle diagram is the condenser.The red __6___ inside the piping represent discharge vapor.The solid red color represents high pressure liquid refrigerant. Most air cooled refrigeration systems are designed so that the refrigerant will condense at a _____7________ about 25 to 30 _____8____above the ambient air temperature around the condenser.Most ____9___ cooled systems are designed for 75° to 95° entering condenser water temperature, with 85° being the design temperature.With water cooled condensers, refrigerant should condense at a temperature about 10° above leaving condensing water temperature, or 20° above entering condenser water temperature.When the hot refrigerant vapor discharged from the compressor travels through the condenser, the cool ___10____ or water flowing through the condenser coil absorbs enough heat from the vapor to cause it to condense. If the outside air temperature is 80°, an air cooled system is designed so that the temperature of the refrigerant, right at the point where it first condenses, will be about 105° to 115°.If the entering condenser water temperature is 85°, a water cooled system is designed so that the temperature of the refrigerant, right at the point where it first condenses, will be about 105°. Why do we want the refrigerant to condense at this relatively high temperature?So that the air or water flowing through the condenser will be very cold relative to the temperature of the discharge ____11______,Which will allow the heat energy in the vapor to move into that relatively cold air or water,And cause the refrigerant to condense. At this stage in the refrigeration cycle, high pressure liquid refrigerant will flow down the liquid line, through a filter drier that is designed to prevent contaminants from flowing through the system, and on to the metering device. The metering device, on this refrigeration ____12____ diagram, is the dividing point between the high pressure and low pressure sides of the system,and is designed to maintain a specific rate of flow of refrigerant into the low side of the system.If the wrong ____13________ of metering device is used, or if there is a problem with the metering device,An incorrect quantity of refrigerant will flow into the evaporator.When the high pressure liquid refrigerant passes through the metering device, its pressure will drop to a low pressure that will be equivalent to about 10° to 15° below the design temperature of the ______14_______.It starts evaporating immediately,and it wouldn't be too inaccurate to imagine it acting like warm soda when you shake the bottle and pop the top off.It shoots out into the evaporator foaming, bubbling, and boiling,And remember, it's at a low pressure, so for a freezer it would be boiling at about -10° to -15°, and for a medium temperature refrigerator it would be boiling at about 25°. And that brings us to the evaporator, in the refrigeration cycle ___15_______.There will be relatively warm air (or water, if the unit is an ice machine) flowing over the evaporator coil. The refrigeration system is designed so that the refrigerant will evaporate in the evaporator at a temperature that's about 10° to 15° below the temperature setting if it's a refrigerator or ____16______, and the temperature will drop to around 0° in the evaporator of an ice machine or ice cream ____17____.The system is designed so that the heat in the relatively warm air, water or ice cream mix flowing over the evaporator will move into the cold evaporating refrigerant. This process will continue to cool the air, water, or ice cream mix that's flowing over the evaporator until it reaches the ___18_____ set point or thermostat setting.So, when you turn on the ____19_____, freezer, ice machine or ice cream machine, the system is designed so that the evaporator will stay colder than whatever it's cooling, and will continuously remove ___20____ from it and cool it.
11
Fill in the gaps with ,
,
,
or
(if
no article is required).
A, an, some, any and the A and an are used with singular countable nouns. A is used before consonants; an, before vowels. A cat An ocean An orange bike Have a look at the following examples:
I need __________ volunteer to sweep the sitting-room and the kitchen. Let's buy __________ grapes for the party. May I have __________ water, please? There aren't __________ strawberries.
An hour (Please note that the h is silent; therefore, hour starts with a vowel sound.) A hot dog (The h is not mute here.) A university student ("University" does not begin with a vowel sound, but, with a consonant sound. It is equivalent to saying you in English.) An unusual situation (The letter u has a vowel sound here.)
It was __________ easy exam. Everybody The plural of a or an is some: Some cats Some oceans
passed it. There is __________ lady at the door who asks
Some is also used with uncountable nouns: some milk.
for you.
In questions and in negatives sentences, any is used instead of some: There wasn't any milk. Has she sent you any photos?
We don't have __________ coke. She hasn't got __________ friends "Are there __________ trees?" "No, there aren't __________ (trees). It's a desert place." __________ elephants never forget.
Fill in the gaps with ,
,
,
,
or
(if no article is required).
__________ onions aren't in __________ cellar. They are in __________ kitchen. __________ whales and __________ elephants are __________ biggest mammals on earth. There were __________ books and __________
However, when we expect a positive reply or when we are offering or asking for something, we use some instead of any: Would you like some coffee? Is there some ham in the fridge, mum? I'm very hungry. (The speaker wants to eat some ham, so he expects that his or her mother will say "yes".) The is used to refer to things previously mentioned or to refer to something unique: A man and a woman were walking along the path. The man was wearing a red jumper and the woman, a pink jacket. I would like to go to the moon. Some, any and the are omitted when the n ames express a general idea: I love bananas. Milk is very good for children.
REGLA 1 No se utiliza el artículo con nombres de países nombres de los continentes, ciudades, lagos, montañas y calles. Sin embargo existen algunas excepciones a esta regla, por ejemplo: the United States , the Netherlands , the Philippines .
REGLA 2
No se utiliza el artículo con determinadas expresiones de tiempo:
►
Pero con muchas expresiones de tiempo comunes, utilizamos el artículo 'THE': ►
12 REGLA 3 No se utiliza el artículo cuando hacemos referencia al nombre de un deporte:
Description of the Refrigerator
Parts 1. “Ice twister” 2. Ice storage recipient 3. Retractable shelf 4. TURBO-FREEZING compartment 5. Freezer compartment bulb 6. Freezer shelf 7. Fast drink cooling drawer 8. Bottle or container support 9. Electronic panel 10. Freezer door shelves 11. Fresh foodstuff compartment 12. Refrigerator compartment bulbs 13. Refrigerator temperature control selector switch 14. Deodorizer 15. Removable glass shelves (2 per refrigerator) 16. Folding glass shelf 17. Partition 18. Multi-use drawer 19. Egg-holder
20. Multi-use drawer 21. Extra fruit drawer 22. Humidity control 23. Fruits/vegetables drawer 24. Mobile partition of the fruits/vegetables drawer 25. Leveling feet 26. Dairies-holder 27. Removable container-holder 28. Small multi-use shelf 29. Medium Multi-use shelves 30. Condiments shelf 31. Bottle holder shelves 32. Freezer door shelf 33. Large bottles lock 34. Small bottles lock 35. Water Reservoir 36. Water Reservoir cover 37. Water tap 38. Water tap lock 39. Water-drop collector 40. Stainless-steel doors
Electronic Panel
1.ALARM OFF key: The refrigerator has four types of alarm: 1.1 OPEN DOOR Alarm After about 2 minutes of the door being open the alarm is triggered.The alarm is automatically turned off when closing the door. To silencethe alarm while leaving the door open, press the ALARM OFF key. The alarm will remain off for 5 minutes. Note: In case of any the doors remaining open, the alarm will again betriggered after the silence period is over. 1.2 TURBO-FREEZING Alarm (Periods of 1:00, 1:30 and 2:30)At the end of the selected TURBO FREEZING period, the alarm willbe triggered, sounding for about 10 seconds. To turn off the alarm, justopen and close the
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freezer door.The alarm can also be turned off pressing the ALARM OFF key (notneeding to open the door in this case). 1.3 Freezer Food Alarm (Periods of 30 to 45 minutes) This alarm cannot be deactivated by the “ALARM OFF” key. At the end of the selected TURBO FREEZING period, the alarm will betriggered, sounding for about 1 minute. In this case, if the door is notopened, an alert “bip” will sound every minute. The only way to silencethis “bip” would be to open the freezer door. 1.4 Fast Drinks Cooling Alarm (DRINK EXPRESS) This alarm cannot be deactivated by the “ALARM OFF” key. At the end of the pre-set period for the chosen drink express cooling,the alarm will sound for one minute. To turn off the alarm, remove thedrink and close the door. If this procedure is not followed, after 1 minute,5 alert “bips” will sound every minute.
2.Open
door Indicator:This indicator stays on as an alert while any of the doors (refrigeratoror freezer compartment) remains open.
3.DRINK EXPRESS key (for express drink cooling):By pressing this key you can select the type of drink to be cooled morerapidly during the pre-set time for each drink. In case you wish to interruptthis function, just press the DRINK EXPRESS key again unti l theindicator displays 0:00 minutes. Attention: The “Drink Express” function may suffer time alteration dueto electrical power fluctuation and environment temperature. Avoidopening the freezer door too often when this function is in use.
4.Drinks Indicator:Shows the drink selected for Rapid Cooling: wine, soft drink or beer. 5.TURBO
FREEZING or DRINK EXPRESS time selection display:In case of having chosen the TURBO FREEZING or DRINK EXPRESSfunction, this display shows the time remaining to conclude the operation.e.g. 30, 29, 28 minutes and successively on until zero (0:00).Should you wish to use the two functions simultaneously (cool drinksand freeze food), the counter will show the remaining time to concludeeach function with a respective display light for 30 seconds and then remainalternating in-between functions until one of them is concluded. When the display is not active, three bars (---) will remain in motionfrom bottom to top.In case you wish to turn off the three bars (---), just press the ALARMOFF key for 5 seconds. Should you wish to turn them back on, repeatthe operation for 5 additional seconds. Attention: This will not turn off the product and just the motionbars will disappear!
6.TURBO FREEZING Indicator:Remains on when the function is active. 7.TURBO FREEZING key: Allows for faster food cooling or freezing . This function’s operationtime can be set to 30 minutes (minimum) and up to 2 hours and 30minutes (maximum). Other periods that may be selected: 45 minutes, 1 hour and 1 hour 30minutes. In case you wish to interrupt this function, just press the TURBOFREEZING key again until the i ndicator displays0:00 minutes. Attention: The TURBO FREEZING function will not run while the DRINK EXPRESS function is active or had been selected first.
8.Freezer Compartment Temperature Selection Displays:They indicate the selected temperature in the freezer compartment.Pressing the FREEZER TEMP. Key makes the setting.When the freezer is turned on for the time, for example, reconnectedafter cleaning, the control will always display MEDIUM position.
9.FREEZER
TEMP. Key:This key allows the freezer compartment temperature to remain betweenMinimum, Medium or Maximum.
Questions: How many types of alarm does this refrigerator have and what are they? What is the function of the open door indicator? When isthe TURBO FREEZING Indicator OFF? What are the MINIMUN and MAXIMUN set for the TURBO FREEZING key?
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What does the Freezer Compartment Temperature Selection Displays show? How many sets does the FREEZER TEMPERATURE KEY have? THE ADJECTIVE An adjective makes the meaning of a noun or a pronoun more specific by highlightingone of its qualities (descriptive adjective) or by imposing boundaries on it (limitingadjective). a hot iron. (descriptive)ten computers. (limiting)his desk. (limiting) Limiting Adjectives Limiting adjectives include these categories: Articles (a , an, the) Demonstrative adjectives (this, that, these, those) Numerical adjectives (two, first )
Possessive adjectives (my, your, his, her, its, our, their ) Indefinite articles (all, none, some, any)
Also, we can say that an adjective is a word used to modify a noun or a pronoun. Tomodify: means “to describe or make more definite” the meaning of a word. Adje ctivesmay modify nouns or pronouns in one of three different ways. 1. By telling what kind:personal computer, operating systems, power electronics 2. By pointing out which one:those pumps, this project 3. By telling how many: ten boxes, several books
TIPS FOR USING ADJECTIVES Unlike many other languages, adjectives in English have only one form. Do not add – s or – es to an adjective to make it plural. The long trip.The long letters. Capitalize adjectives of origin (city, state, nation, continent). The Venetian canals.The Mexican hat.The French government.The African desert. In English, verbs of feeling (for example, bore, interest, surprise) two adjectival forms:the present participle (-ing) and the past participle (-ed). Use the present participle todescribe what causes the feeling. Use the past participle to describe the person whoexperiences the feeling. We heard the surprising election results. Only the candidate was surprised by the election [The election results cause thefeeling.] results. [The candidateexperienced the feeling of surprise.] Adjectives follow the noun in English in only two cases: when the adjective functions as a subjective complement, as in That project is not finished
And when an adjective phrase or clause modifies the noun, as in The project that was suspended temporarily……. In all other cases, adjectives are placed before the noun.
When there arte multiple adjectives, it is often difficult to know the right order. The guidelines illustrated in the following example would apply in most circumstances, but there are exceptions. (Normally do not use a phrase with so many stacked modifiers.)
Quantifier
Article Possessive Demonstrative
Number Sequence
Quality Size
Shape
Color
Origin
Material
Some of All of Both
the, a, an this, that my, his
three second next
wonderful clean large
round square flat
red yellow black
Japanese Italian French
metal ceramic wood
Examples: Some of the hungry gentlemen
The beautiful Japanese ceramic vase
The last great civilization
Either of the small green apples
Ten big round metal rings
My three lovely daughters
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An interesting wooden statue
The third red plastic container
Selecting the refrigerant Originally when the modern refrigerating system concept was developed in the middle of the 19th Century, a small number of fluids were used as the working fluid, or “refrigerant”. These included ammonia (NH3, R717), carbon dioxide (CO2, R744), sulphur dioxide, methyl chloride and ethyl ether. However, because of the combination of toxicity, flammability and pressure issues, these refrigerants were largely replaced with to a “new” group of fluorinated chemicals which exhibited little reactivity, low -toxicity and no flammability. However, during the 1980s, it was found that these chemicals contributed to the depletion of the ozone layer, which lead to the development of the Montreal Protocol in 1987. The Montreal Protocol requires the cessation of the consumption and production of all chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) and since its introduction, the refrigeration and air conditioning (RAC) industry has been engaged with the chemical community to establish substitutes for ozone depleting refrigerants. Throughout this time a large number of refrigerants have been introduced worldwide, of which some are long term alternatives, and others are “transitional” substances. With the increasing attention paid to the issue of global warming a nd climate change, there is now a stronger push towards adopting alternative refrigerants with low or no global warming potential (GWP), as well as zero ozone depleting potential (ODP). With the continued attention on replacement refrigerants, coupled with the ever growing market for RAC, there are now several hundred refrigerants that are currently commercially available. Such a diversity of refrigerants and their variety of different characteristics can create difficulties in handling and servicing practices for many RAC technicians. This section aims to introduce an overview of refrigerants and their characteristics, classifications, applications, identification and lubricants. There are usually two situations that necessitate refrigerant selection, the first being for manufacture of systems, and the second being equipment servicing. For manufacturing RAC equipment, the refrigerant selection process is theoretically complex, involving the consideration of huge number parameters. Chemical properties and stability The stability of a refrigerant is linked to the way it behaves in the presence of other substances, particularly within the refrigerating system. It is important that the refrigerant will not react with, or act as a solvent with, any of the materials within the system. These include metals used for pipes and other components, compressor oils and associated additives, plastic motor materials, elastomers in valves and fittings, and desiccants within filter dryers. This should also be considered with respect to the small quantities of contaminants such as moisture and air. In general CFCs, HCFCs, hydrofluorocarbons (HFCs) and HCs are compatible with most materials (since most components are designed for these refrigerants). However, many components are designed using proprietary mixtures and additives, so there is always a possibility of incompatibility with certain materials if an unspecified refrigerant is used. Carbon dioxide has some compatibility problems with certain elastomers, which is why only dedicated components for R744 should be used with this refrigerant. Ammonia is not compatible with many materials, such as copper, copper alloys and many electrical wiring insulation materials. Therefore construction metals inside ammonia systems are normally limited to carbon steel and stainless steel. In all cases, component manufacturers should be consulted to check that their materials are compatible with a non-standard refrigerant. Operating pressures It is important to consider the likely operating pressures in both the suction and discharge sides of the system. Ideally, a refrigerant is chosen that will have an evaporating pressure above atmospheric pressure under normal operating conditions, so as to avoid air and moisture being drawn into the system in the event of a leak. Thus, a refrigerant should be chosen with a normal boiling point (NBP) that is lower than the anticipated evaporating temperature. A selected refrigerant should also have a condensing pressure that does not exceed the pressure that the system components are designed for, as this can have safety implications. Thermodynamic and transport properties The most important performance criteria for a refrigerating system are cooling (or heating in the case of heat pumps) capacity and efficiency, or coefficient of performance (COP). These performance characteristics are influenced by a number of properties, including: • saturation pressure-temperature characteristics • critical temperature • latent heat • density • viscosity • thermal conductivity • specific heat capacity
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It is important to consider the likely operating pressures in both the suction and discharge sides of the system. Ideally, a refrigerant is chosen that will have an evaporating pressure above atmospheric pressure under normal operating conditions, so as to avoid air and moisture being drawn into the system in the event of a leak. Thus, a refrigerant should be chosen with a normal boiling point (NBP) that is lower than the anticipated evaporating temperature. A selectedrefrigerant should also have a condensing pressure that does not exceed the pressure that the system components are designed for, as this can have safety implications. The capacity and COP are mainly dictated by the design and control of the system itself (compressor, heat exchangers, piping, etc), although the properties of the refrigerant play a part in this. The COP can be affected by the compression ratio (which is dictated by the saturation pressure-temperature characteristic), heat exchanger performance and pressure losses around the system, which are all influenced by latent heat, density, viscosity, thermal conductivity, specific heat. For a given evaporating and condensing temperature, the cooling (or heating) capacity of a system is strongly influenced by the latent heat and density of the gas entering the compressor. For conventional systems, a fairly high critical temperature is preferred (at least 20K above the condensing temperature), unless the system is specially designed for operation near or above the critical temperature, such as with R744 system
Refrigerant cylinders or drums are often colour coded. The colour code is normally a voluntary precaution followed by refrigerant suppliers. However, it should be noted that different colour codes are used in various parts of the world. Refrigerant cylinder colour codes according to ARI (2008)
Match the following concept to de correct definition ___a.carbon dioxide ___ b. Refrigerant ___d. global warming ___e. fluid ___g. viscosity ___ h. temperature ___i. pressure ___ j. density ___k. heat ___ l. boiling
___c. ozone ___f. pipe
1.The application of heat to change something from a liquid to a gas. 2. A colorless, odorless, incombustible gas, formed during respiration, combustion, and used in food refrigeration. 3. Substance used in refrigerating systems. 4.The current rise in the average temperature of Earth' s oceans and atmosphere. 5. Highly reactive oxidizing agent used to deodorize air, purify water, and treat industrial wastes. 6. A substance, such as a liquid or gas that can flow. 7. A long tube of metal, plastic, etc., used to convey water, oil, gas, etc. 8. The state or property of being viscous. 9.The transfer of energy from one body to another as a result of a difference in temperature. 10. Force applied uniformly over a surface. 11. It’s a measure of how much mass is contained in a given unit volume. 12. a measure of the quantity of heat in an object, usually as measured on a thermometer.
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Word formation
Prefix
Meaning
Example
before
They will show a sneak preview of the movie.
not
The cafeteria will be unavailable tomorrow morning.
not
Mark disagreed with John's philosophy.
again
Are you going to renew your subscription?
not
He has mismanaged the company.
not
With hard work and determination, nothing is impossible .
two
Henry recently received his first pair of bifocals .
not
Many ecologists are concerned about the deforestation of our world's rain forests.
Suffixes
Meaning
Example
doer
I work as a computer programmer .
able
These glass bottles are recyclable .
full of
Driving on the freeway can be dangerous .
state of being
At night, the earth is covered in darkness .
full of
The witness gave an honest and truthful testimony.
like
James whistled happily on his way home from school.
state of
Mary sighed with contentment .
A. Match prefixes on the left to their meanings on the right.
___Multi- (multiple) ___ Re- (renew) ___ Pre- (preview) ___ Mis- (misbehave) ___ De- (deforestation) ___Tele- (television) ___ Un- (unhappy) ___ Bi- (biweekly) ___Uni- (uniform) ___Sub- (subway)
1) wrong, bad 2) before 3) again, back 4) eight 5) one, same, whole 6) remove or reduce 7) twice, (two times) 8) far, distant
9) many, (usually more than two)
10) under or low 11) not
B. Circle the best available answer for each of the following :
1) This newspaper is a BIWEEKLY. a) the newspaper is published once a week b) the newspaper is published three times a week c) the newspaper is published twice a week 2) This medicine is a nasal DECONGESTANT. a) the medicine helps to reduce nasal congestion b) the medicine causes nasal congestion c) the medicine makes your nose bigger 3) That shopping bag is REUSABLE. a) throw the shopping bag away, we won’t need it again b) don’t throw away the shopping bag because we can use it again. c) if you throw the shopping bag we cannot use it again 4) I’m sorry I MISREAD the notice and therefore MISUNDERSTOOD the message. a) Did not read the notice correctly and therefore did not understand correctly. b) Read the notice and understood the message correctly c) Did not read the notice and therefore did not understand the message. 5) We usually do not publish articles we don’t PREVIEW.
a) we usually read articles before publication b) we do not read articles after publication c) we read articles the day we publish them 6) REFORESTATION will help to RESTORE our environment. a) planting trees again will REPLENISH our environment. b) cutting down trees will further help to worsen the environment. c) forests should be cut to improve the worsening environmental pollution 7) DEFORESTATION will cause environmental DEPLETION. a) Means planting trees will help our environment from DEPLETION b) Means cutting down trees will cause further environmental DEPLETION c) Means too many forests will cause further environmental DEPLETION 8) Why is it called “OCTOBER” when it is not the e ighth month of the year? a) Because this is an exception with the OCTO prefix. b) There is no reason why. c) Because October used to be the eighth month of the Roman Calendar
Loads are electric devices that consume electricity to do useful work. Loads are devices such as motors (Fig. 5.1), solenoids (Fig. 5.2), resistance heaters (Fig. 5.3), and other current-consuming devices. The sizes of loads vary from devices with a small current draw, such as a light bulb, a small fan motor, and solenoids, to large motors that could use upward of 100 amperes .
(left) Electric motor; (right) A solenoid used to operate a contactor
A resistance heater (Courtesy of Indeeco, St Louis, MO
Loads are the most important part of a heating, cooling, or refrigeration system because they do all the work in the system. Loads operate compressors, which compress and transfer refrigerant in a system. They operate fans, which move air. They operate the solenoid part of a relay, which starts and stops loads. Also, loads operate with other devices that perform useful work. Industry technicians should be able to recognize the common symbols for loads and know where to look up the symbols for little-used loads, because each electric wiring diagram is composed of symbols and their interconnecting wires.In the following paragraphs, we will take a close look at several different kinds of loads used in the industry.
A motor is an electric device that consumes electric energy to rotate a device in an electric system. Motors are used in the industry to rotate devices such as compressors (Fig. 5.4), condenser fan motors (Fig. 5.5), pumps (Fig. 5.6), and other devices that require rotating movement. Motors are the largest and most important loads in heating, cooling, and refrigeration systems.
Compressor (Courtesy of Copeland, Sidney, OH); A condenser fan motor on a residential air- conditioning condensing unit (Courtesy of American Standard Air Conditioning)
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The symbols shown in Fig. 5.7 are the most common symbols used to represent motors.
A letter designation tells you what purpose the motor serves in the sys tem. Fig. 5.8 shows several symbolic representations of different uses of motors. Careful attention should be given to symbols representing motors because in some cases, a motor has an internal overload, as shown in Fig. 5.8(e).
FIG. 5.6 A centrifugal pump (Courtesy of Peerless Pump Co., Indianapolis, IN)
FIG. 5.7 Symbols for an electric motor FIG. 5.8 Symbols representing some common uses of motors: (a) Condenser fan motor, (b) Evaporator fan motor, (c) Compressor motor, (d) Compressor motor, (e) Compressor motor with internal overload.
The solenoid is a device that creates a magnetic field when energized and causes some action to an electric component such as a relay or valve. A common solenoid used to operate a relay is shown in Fig. 5.9. The solenoid is considered a load because it consumes electricity to do useful work. Solenoids are devices that control some element in a system. Solenoid valves are valves that open and close, stopping or starting a flow. Solenoid coils used in relays and contactors will be discussed later in this section. Some common solenoid valves are hot-gas solenoids, reversing valve solenoids, and liquid-line solenoids. Fig. 5.10(a) shows a solenoid valve and a solenoid coil, and Fig. 5.10(b) shows its symbol.
FIG. 5.9 Solenoid coil used to operate relay
FIG. 5.10 (a) Solenoid valve with coil (Courtesy of Sporlan) (b) Symbol Heaters Heaters are loads that are found in many systems and wiring diagrams. A heater takes electric energy and converts it to heat. In some cases, electric resistance heaters are used to heat homes. Heaters might also be used to heat a small object or area. The symbol for all heaters is the same. Only a letter designation tells you specifically why the heater is used. Fig. 5.11 shows the symbols used for heaters, along with some common letter designations.
A signal light is a light that is illuminated to denote a certain condition in a system. The letter inside the signal light symbol denotes the color of the signal light, as shown in Fig. 5.12. Signal lights come in a variety of colors and are not limited to the colors
20
shown in Fig. 5.12. A signal light is used to show that a piece of equipment is operating or that it is operating in an unsafe condition. Signal lights are usually energized when a piece of equipment or component is started.
FIG. 5.11 Symbols for commonly used electric heaters: (a) Heater, (b) Crankcase heater, (c) Supplementary heater
FIG. 5.12 Symbols for signal lights showing the color of the light: (a), Red, (b) Green, (c) Blue
Contactors and relays are devices that open and close a set or sets of electric contacts by the action of a solenoid coil. The contactor or relay is com posed of a solenoid and the contacts. A relay is shown in Fig. 5.13. A contactor is shown in Fig. 5.14. When the solenoid is energized, thecontacts will open or close, depending on their original position (that is. if they were open, they will close, and vice versa).
Relay (Courtesy of Siemens Electromechanical Components, Inc.): Mechanical linkage; Solenoid coil; Normally-open contacts; Normally closed contacts
Contactor In an air-conditioning control system, we must have some method of con trolling loads. In most cases, a relay or contactor is used. Relays and contactors are widely used in control systems. Thus, it is essential that industry technicians be able to identify the symbols for relays and contactors. The main difference between a relay and contactor is the size of the device. A contactor is simply a large relay. Usually, the devices are distinguished by their rated current flow. A contactor can carry 20 amperes or more. A relay is designed to carry less than 20 amperes. Contactors are commonly used where the ampere draw of a device is more than 20 amperes. A relay would rarely be used to carry over 20 amperes. Contactors and relays play an important part in the control system of any air conditioner, refrigerator, or heater. For example, contactors and relays are used to stop and start different loads in a refrigeration system. Compressors, in most air-conditioning systems, are controlled by a contactor or magnetic starter. Relays can be used for pilot duty, that is, for con trolling another relay or contactor. The most important fact to remember is that most control systems have many relays and at least one contactor. These relays or contactors always control some load. Relays and contactors are composed of three parts: the contact and the coil, or solenoid, and the mechanical linkage. The contact makes the electrical connections. Fig. 5.15 shows the symbol for a pole, or contact, of a relay or contactor. The term “pole” refers to one set of contacts. However, in some cases the relay or contact might have two or three poles, which means two or three sets of contacts. The coil or solenoid, the second part of the relay, is energized (voltage is supplied) and, through a magnetic field, closes the contact or contacts. Either symbol shown in Fig. 5.17 can be used to represent a relay or contactor coil. The symbol for the relay or contactor is the same if each has the same number of poles and if their purpose is basically the same, with the exception of the ampere rating of the device.
21
All symbols are usually shown in the de-energized position. This means that there is no electric potential to the coil of the device. Fig. 5.15 shows a “normally open” contact in the de-energized position.
FIG. 5.15 Symbol for a normally open pole of a relay . FIG. 5.16 (bottom) Symbol for a normally closed pole of a relay or contactor.
FIG. 5.17 Symbols for relay or contactor coil; either symbol may be used for each device.
FIG. 5.18 Normally closed and open set of contacts (Courtesy of Siemens Electromechanical Components, Inc.) The term normally refers to the position of a set of contacts when the device is de-energized. Fig. 5.15 shows a normally open set of contacts and Fig. 5.16 shows a normally closed set of contacts. Normally open contacts close and normally closed contacts open when the relay or contactor is energized. In Fig. 5.18, a relay is shown with normally open and closed contacts. The terms “normally open,” “normally closed,” “energized,” and “de energized” are important in understanding relays and contactors on wiring diagrams. Fig. 5.19(a) shows a relay with two normally open contacts and one normally closed contact in the de-energized position (with no volt age to the coil). Fig. 5.19(b) shows the same contacts in the energized position (with voltage to the coil). In the de-energized position, the current will not flow through contacts 1 and 2, but current will flow through con tact 3. In the energized position, the current flow is through 1 and 2 but not through 3.
Fig. 5.19 Symbols showing de-energized and energized relays
A magnetic starter is the same type of device as a contactor in terms of the ampere rating of the device. But the magnetic starter has a means of overload protection in it, whereas the contactor has none. Fig. 5.20 shows a picture of the magnetic starter and its symbol. The principle of operation of the magnetic starter will be covered in an upcoming section.
An electric switch is a device that opens and closes to control some load in an electric circuit. Electric switches can be opened and closed by temperature, pressure, humidity, flow, or by some manual means. You must become familiar with the symbols used for switches because in most cases they control the loads in the system. The symbol will also indicate what is initiating the action of the switch.
FIG. 5.20 (a) Magnetic starter (Courtesy of Furnas Electric Company) (b) …and its symbol A manually operated switch is a switch that is opened and closed by manual force. Fig. 5.21 shows a simple manually operated switch. The poles
22
of a manual switch are the number of contacts that are included in the switch. The throw indicates how the switch may be operated. For example, a single-pole—single-throw switch has one set of contacts and two positions: an open and a closed position, as shown in Fig. 5.21. A double- pole—double-throw switch has two sets of contacts and three positions, as shown in Fig. 5.22. Symbols for these two switches and for two other basic types of manual switches are shown in Fig. 5.23.
ingle-throw manual switch FIG. 5.22 Double-pole—single-throw manual FIG. 5.21 Single-pole —s
switch FIG. 5.23 Symbols for manual switches: (a) Single-pole — single-throw switch; (b) Single-pole-double-throw switch; (c) Double-pole-single-throw switch; (d) Double-pole-double-throw switch
FIG. 5.24 Three-pole fusible disconnect: (b) Symbol; (a) Switch There are other types of manual switches used in the industry. The disconnect switch is used to open and close the main power source to a piece of equipment or load. Fig. 5.24 shows a three-pole disconnect switch and its symbol. The push-button switch, as shown in Fig. 5.25, is a switch used to open and close a set of contacts by pressing a button. The symbols for the normally closed and the normally open push-button switches are also shown in Fig. 5.25.
23
The most important type of switch in a control system is the mechanically operated switch. Thermostats are mechanically operated switches used in most control systems. Thermostats are said to be mechanically operated because the temperature-sensing element moves a set of contacts by a mechanical linkag e. Thermostats are designed for heating, cooling, or both. The cooling thermostat is designed to close on a temperature rise and open on a temperature fall. The heating thermostat is designed to open on a temperature rise and close on a temperature fall. The symbols for these two types of thermostats, shown in Fig. 5 .26, indicate their function. Fig. 5.27 shows a modern thermostat.
FIG. 5.27 Thermostat (Courtesy of Honeywell, Inc.)
FIG. 5.28 Symbols for pressure switches: (a) Opens on rise in pressure; (a) Closes on rise in pressure Pressure switches are used for different functions in modern control circuits. The purpose of the pressure switch determines whether it opens or closes on a rise or fall in pressure. The pressure range of the switch i s not part of the symbolic repres entation. Fig. 5.28 shows the symbols for pressure switches. Letter designations in the symbols often denote the pressure ranges and purposes of the switches. Fig. 5.29 shows some common pressure switches used in the industry.
FIG. 5.29 Some common pressure switches
Safety devices are important in today’s modem systems. Components are becoming more expensive each year. Thus, it is vital that these components be protected from adverse conditions such as low voltage, high ampere draw, and overheating. It is for this reason that you should become familiar with symbols for safety devices. Overloads and safety devices are some times a combination of a load and a switch. They differ from the relay in their purpose and overall design. All motors are designed to operate on a certain current draw. If for some reason this rating is exceeded, the motor must be cut off immediately to prevent damage and possible destruction of the component. A burned-out motor is often caused by a malfunction in the safety devices. The fuse is the simplest type of overload device. The fuse is effective against a large overload, but it is less effective against small overloads. The fuse is nothing more than a piece of metal designed to carry a certain load. Any higher load will cause the fuse to break the circuit. Fig. 5.30 shows two symbols for a fuse. Fig. 5.31 shows some common fuses in use today.
FIG. 5.30 Symbols for fuses; FIG. 5.31 Some common fuses The second type of overload device is designed to protect the motor against small and large overloads. This type is divided into two categories: thermal and magnetic. The thermal overload is operated by heat, and the magnetic overload is operated by
24
magnetism, which is directly proportional to the current draw. The thermal overload can be a pilot duty device, which breaks the control circuit and locks the motor out. The pilot duty types of overloads are most common on motors larger than 3 horsepower. The thermal overload can also be a line voltage device, which breaks the power line to the component being protected. The bimetal element is the simplest of the thermal overloads. When it gets warm, it warps to open the circuit, as shown symbolically in Fig. 5.32. Some bimetal elements are furnished with heaters, as shown symbolically in Fig. 5.33. The heater allows the bimetal disc to react to an overload more quickly because the current flow is proportional to heat.
FIG. 5.32 Symbols for bimetal overload (closed and open); FIG. 5.33 Symbol for three-wire bimetal overload The thermal overload relay, whose symbol is shown in Fig. 5.34, is a simple device with a thermal element and a switch that opens on a rise in temperature.
The magnetic overload symbol is the same as the symbol for a relay with one normally closed contact. The current flow is relayed to the overload coil. Since current flow is proportional to the strength of the magnetic field, the relay can be designed to energize only on a high current draw. Fig. 5.35 shows a magnetic overload and its symbol. The letter designation of this device will distinguish between the magnetic overload and the common relay.
FIG. relay;
5.34
Symbol FIG.
for 5.35
thermal Magnetic
overload overload
device
The transformer decreases or increases the incoming voltage to a desired voltage. In most air-conditioning control circuits, it is not practical to pull large wires for a long distance. Therefore, a 24-volt control circuit, which is safer, less expensive, and a better method of control, is used. Fig. 5.36 shows a transformer and its symbol. The voltage is also given with the symbol in some cases.
FIG. 5.36 Transformer: (a) Symbol; (b) Transformer
Most modern heating, cooling, and refrigeration systems are becoming more complex with more controls and safety devices. Advances in controls and control systems require you to be able to read schematic diagrams. If you are able to read schematic diagrams, you will know what the unit should be doing. The schematic diagram is the most useful and easiest to follow of any electric diagram. The schematic diagram tells how, when, and why a sys tem works as it does. In most cases, service technicians use schematic diagrams to troubleshoot control systems. The schematic wiring diagram includes the symbols and the line representations so the user can easily identify loads and switches along with the circuits. All electric circuits contain a source of electrons, a device that uses electron flow, and a path for the electrons to follow. In most cases, the source of electrons is an alternating current voltage supply. The device using the electron flow is a motor, heater, relay coil, or any other load device. The path for the electrons to follow is a wire or any type of conductor.In the schematic diagram, the source of electrons, the power supply, is represented by two lines drawn downward and listed as L1 and L2, as shown in Fig. 5.37. There is a potential difference of 240 volts between L1 and L2. If a path is created between Li and L2, current will flow.
FIG. 5.37 Schematic diagram showing power supply All electrical loads in the unit are placed between L1 and L2, along with the switches controlling the load. Fig. 5.38 shows a complete circuit in schematic form with a compressor and the switch (thermosta t) that controls it. When the switch is closed, the compressor will run. In Fig. 5.38, the source of electrons is from L1 and L2, the path is the connecting wire, and the device using the electron flow is the compressor. The compressor operates when the thermostat is closed.
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Fig. 5.39 shows a full schematic diagram similar to the diagrams you will be using on the job. All schematic diagrams are broken down into a circuit-by-circuit arrangement. Most schematic diagrams contain a legend that cross-references the components and their letter designation to the name of the component. Look at the legend in Fig. 5.39.
FIG. 5.38 Schematic diagram of a complete circuit: Control switch (thermostat); Compressor; run capacitor
Legend:
Symbols:
IF: Indoor fan motor IFR: Indoor fan relay M: Contactor OL: Overload HP: High-pressure switch
Wiring:
LP: Low-pressure switch
FIG. 5.39 Complete schematic diagram for small packaged unit (Courtesy of Westinghouse Electric Corp.)
The pictorial diagram, also referred to as a label or line diagram, is intended to show the actual internal wiring of the unit. The pictorial diagram shows all the components of the control panel as a blueprint, including all the interconnecting wiring. It does not show the unit to scale, however. Components that are not shown in the control panel itself are shown outside the panel and labeled. The pictorial diagram is used to locate specific components or wires when troubleshooting from a schematic diagram. A typical pictorial diagram used in the industry is shown in Fig. 5.40.
FIG. 5.40 A typical pictorial diagram used in the industry (Courtesy of Carrier Corporation, Syracuse, NY)
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1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. (35-47)
BLWR BLWM CAP CPU EAC-1 EAC-2 FRS FSE FU FU2 GV GVR HIILO HG HSIR HUM IDM IDR ILK JB LED LOPS LS OL PCB PL1 PL2 PL3 PL4 PL5 PRS SW S2 TEST/TWIN TRAN
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47.
BLOWER MOTOR RELAY, SPST-(N.O.) BLOWER MOTOR CAPACITOR MICROPROCESSOR AND CIRCUITRY ELECTRONIC AIR CLEANER CONNECTION (115 VAC 1.5 AMP MAY.) ELECTRONIC AIR CLEANER CONNECTION (COMMON) FLAME ROLLOUT SW. -MANUAL RESET, SPST-(N.C.) FLAME PROVING ELECTRODE FUSE. 3 AMP, AUTOMOTIVE BLADE TYPE, FACTORY INSTALLED FUSE OR CIRCUIT BREAKER CURRENT INTERRUPT DEVICE (FIELD INSTALLED & SUPPLIED) GAS VALVE-REDUNDANT OPERATORS GAS VALVE RELAY, DPST-(N.O.) BLOWER MOTOR SPEED CHANGE RELAY, SPDT HOT SURFACE IGNITOR (115 VAC) HOT SURFACE IGNITOR RELAY, SPST-(N.O.) 24VAC HUMIDIFIER CONNECTION (.5 AMP. MAY.) INDUCED DRAFT MOTOR INDUCED DRAFT RELAY. SPST-(N.O.) BLOWER ACCESS PANEL INTERLOCK SWITCH. SPST-(N.O.) JUNCTION BOX LIGHT-EMITTING DIODE FOR STATUS CODES LOW GAS PRESSURE SWITCH, SPST-(N.O.) LIMIT SWITCH. AUTO RESET, SPST-(N.C.) AUTO-RESET INTERNAL MOTOR OVERLOAD TEMP. SW. PRINTED CIRCUIT BOARD 9-CIRCUIT CONNECTOR 2-CIRCUIT PCB CONNECTOR 3-CIRCUIT 1DM CONNECTOR 3-CIRCUIT 1DM EXTENSION CONNECTOR 2-CIRCUIT HSIIPCB CONNECTOR PRESSURE SWITCH. SPST-(N.O.) BLOWER OFF DELAY COMPONENT TEST & TWIN TERMINAL TRANSFORMER-115VAC / 24VAC JUNCTION UNMARKED TERMINAL PCB TERMINAL FACTORY WRING (115VAC) FACTORY WIRING (24VAC) FIELD WIRING (115VAC) FIELD WIRING (24VAC) CONDUCTOR ON PCB FIELD WIRING SCREW TERMINAL FIELD GROUND EOUIPMENT GROUND FIELD SPLICE PLUG RECEPTACLE
It is difficult to determine from a pictorial diagram how a system operates, and only an experienced mechanic can follow a complex pictorial diagram. Thus, most air-conditioning technicians use the schematic diagram to find the cause of the problem. Then they use the pictorial diagram to locate the position of the component at fault. In cases where the wiring is simple, however, a pictorial diagram may be the only diagram furnished with the equipment. The factual diagram consists of a pictorial diagram along with a schematic diagram. Many air-conditioner manufacturers supply factual diagrams so service technicians can locate the relay or component in the control panel.
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The installation diagram is used to help the installation electrician to wire the unit properly. The diagram gives specific information about terminals, wire sizes, color coding, and breaker or fuse sizes. The diagram does not provide details about equipment operation because the electrician has no need for this information. Fig. 5.41 shows an installation diagram. The installation wiring diagram shows little internal wiring and is therefore almost useless to industry technicians.
Loads are devices that use electricity to do useful work. Fig. 5.42 gives a review of the symbols used for solenoids, motors, and heaters, the typical loads found in the industry. Most symbols have some type of letter designation to identify more clearly the component referred to.
FIG. 5.41 A typical installation diagram: To Power Supply 208/240/1/60; 40VA 24V NEC Class 2 Circuit
FIG. 54.2 Review of symbols for loads: Motor, Solenoid, Heater
FIG. 5.43 Review of symbols used for contactors and relays: Relay; Contactor or three pole relay; Magnetic starter Loads are controlled by relays and contactors, which share the same symbol and perform similar tasks. The major difference between relays and contactors is the amount of current each can carry. If a compressor is being operated by a device, you can assume the device is a contactor. If a small fan motor is being operated by a device, you can assume the device is a relay. A relay is used for small loads, and a contactor is used for large loads. Fig. 5.43 reviews the symbols for some of these devices. Relays and contactors are controlled by switches. Some of the switches used in the industry are manual, push-button, thermostat, and pressure. Thermostats are made for two purposes: to operate either a heating or a cooling system. The symbols for thermostats denote whether they are used for heating or cooling. Pressure switches are much the same as thermostats; their
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symbols also denote which way they open or close and under what condition. Pressure switches can be used for low or high pressure and are usually denoted by letter designations. In any system using motors, protective devices are important to prevent damage to the motors or to larger components of the system. The most important type of safety device is for motor protection. A fuse, magnetic overload, thermal overload line break, thermal overload pilot duty, or a thermal overload relay could be used. Many overloads are built directly into the larger components.Transformers are devices that increase or decrease the incoming voltage to some desired voltage. Transformers are used in the industry mainly in control circuits. Schematic diagrams tell air-conditioning, heating, or refrigeration technicians when and why a system works as it does. Schematic diagrams show the symbols for devices and the interconnecting wiring of a unit in a circuit- by-circuit arrangement. Schematic diagrams are used most frequently by service technicians to troubleshoot equipment and systems. Pictorial diagrams show an exact layout of the control panel with the external components shown outside the panel and labeled. The pictorial diagram can be used as a troubleshooting diagram on a simple system, such as a window air conditioner. In most cases, pictorial diagrams are used to find the placement of a component in the panel. Factual diagrams are a combination of the schematic and pictorial, with each shown separately.Installation diagrams are used to help the installation electrician correctly connect the wiring to the unit. See the dedicated section of this guide for most of the electrical symbols used by major refrigeration, heating, and air-conditioning manufacturers.
REVIEW QUESTIONS 1. What are the three types of electrical diagrams used in the heating, cooling, and refrigeration industry? 2. A load is an electrical device that: a. produces electricity
c. assists in the starting of motors
b. directs the flow of electricity
d. uses electricity to do useful work
3. What is the major load of an air-conditioning system? 4. Identify the following symbols for loads:
5. What is the major difference between a contactor and a relay? 6. What do the terms “normally open” and “normally closed” refer to with regard to a switch or set of contacts? Draw a normally open and normally closed contact. 7. What is the difference between a magnetic starter and a contactor? 8. Identify the following symbols for relays and contactors:
9. Draw a heating and a cooling thermostat and explain the difference between them. 10. A three-pole contactor would allow how many paths for current flow? 11. A disconnect switch is used to _____
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a. open and close the main power source to a piece of equipment
c. control the operation of an electric heater d. open when an unsafe condition occurs
b. stop and start a compressor 12. What determines whether a pressure switch opens or closes on a rise of pressure? 13. Identify the following symbols for switches:
14. What is the difference between a thermal overload and a magnetic overload? Draw the symbol for each. 15. What is the purpose of a trans former? Draw the symbols for a transformer. 16. Which of the following is not a requirement for an electric circuit? a. a source
c. a load
b. a path
d. a signal light
17. What is the purpose of a legend on a schematic diagram? 18. A factual diagram is ___ a. a pictorial diagram with wire colors denoted
c. a combination of schematic and pictorial wiring diagrams
b. a combination of pictorial and installation wiring diagrams
d. none of the above
19. Identify the following symbols for safety devices.
20. Which of the following are not components of a contactor or relay? a. a solenoid
c. thermal element
b. contacts
d. mechanical linkage
21. True or False: The schematic diagram tells service technicians how to wire a system. 22. What is the difference between a pilot duty and a line break overload? 23. What type of switch would be used to open or close set of contacts at a certain pressure?
24. What is the purpose of a fuse in an electrical system? 25. True or False: A solenoid valve is a device that opens or closes to control the flow of some element in the system. 26. What is a signal light used for in a control system? 27. Change the following normally open elements from the de-energized position to the energized position. 28. Draw the symbols for the following electrical devices. a. heating thermostat
c. heater
b. pressure switch (closes on rise)
d. motor
e. solenoid coil f. normally open push-button switch 29. Add letter designations to the symbols to indicate the following: a. compressor —O=
d. crankcase heater —/\/\/\—
b. high-pressure switch
e hot-gas solenoid —\/\—
c. evaporator fan motor —O— f. red signal light
30. Draw a symbol for a magnetic starter
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Glossary ABSOLUTE HUMIDITY - The amount of CROSS CHARGED - Two different fluids used moisture that is in the air; it is measured in grains to create the desired pressure-temperature per cubic foot. relationship. ABSOLUTE PRESSURE - Gage pressure plus CRYOGENIC FLUID - An ultra-low temperature atmospheric pressure (see pressure conversion gas or liquid. table). CRYOGENICS - Refrigeration producing ABSOLUTE TEMPERATURE - The temperature temperatures at or below -250° F. that is measured from absolute zero (-460° F., CURRENT RELAY - A relay which makes or zero° R., and -273° C., breaks a circuit depending on a change in current zero° K.) flow. ACCUMULATOR - A tank that is used to keep DALTON’S LAW - The total pressure of a liquid refrigerant from flowing to the compressor. mixture of gases is the sum of the partial ACTIVATED ALUMINA - A chemical pressures of each of the gases in the desiccant. mixture. ACTIVATED CARBON - Processed carbon that DENSITY - The mass of a substance per unit is used for a filter. volume (consistency). ADIABATIC COOLING - Process of changing DEWPOINT - The temperature at which a sensible heat for latent heat without removing saturated vapor will begin to condense. heat (evaporative cooling). DRY ICE - Solid carbon dioxide at approximately ANEMOMETER - An instrument used to -109° F.; it is used in the shipment of produce. measure the rate of airflow. EBULATOR - A sharp-edged material inserted in ATMOSPHERIC PRESSURE - Pressure that is a flooded evaporator for better efficiency. exerted upon the earth by t he atmospheric gases. FLASH GAS - When changing from a highAUTOTRANSFER - Common turns serve both pressure liquid to a low-pressure liquid some of the primary and secondary coils. Different taps the liquid flashes (evaporates) are used to step up or step off and cools the remaining liquid to the desired down the voltage. evaporation temperature. AZEOTROPIC REFRIGERANTS - These are FOOT-POUND - The amount of work done in mixtures of refrigerants that do not combine lifting 1 pound 1 foot. chemically but provide good GRAIN - A unit of weight; 7000 grains equals 1 refrigerant characteristics. pound. BACK PRESSURE - Low side pressure or HEAD, STATIC - Pressure of a fluid measured in suction pressure. terms of height of the column of the fluid. BOYLE’S LAW - The volume of a given mass of HEAT LOAD - The Btus that are removed in 24 gas varies as the pressure varies if the temperature hours. remains the same. HEAT OF COMPRESSION - The transformation BRITISH THERMAL UNIT - The amount of of mechanical energy of pressure into energy of heat required to raise the temperature of 1 pound heat. of water 1° F. HYDROMETER - An instrument used to CALORIE - The quantity of heat required to raise measure the specific gravity of a liquid. the temperature of 1 gram of water 1° C. HYGROMETER - An instrument used to CASCADE SYSTEM - Refrigeration system measure the ratio of moisture in the air. where two or more systems are connected in INDUCTION MOTOR - An ac motor that series to produce ultra-low operates on the principles of a rotating magnetic temperatures. field. CHARLES’ LAW - The volume of a gas varies KATATHERMOMETER - An alcohol directly with the temperature provided that the thermometer used to measure air velocities by pressure remains constant. means of cooling effect. COEFFICIENT OF PERFORMANCE (COP) KELVIN SCALE (K) - A thermometer scale that The ratio of energy applied as compared to the is equal to centigrade but using zero as absolute energy used. zero instead of -273° C. COMPOUND REFRIGERATION SYSTEM - A (absolute centigrade). system with two or more compressors or cylinders LATENT HEAT - Hidden heat; heat energy that a in series. substance absorbs while changing state. CRITICAL PRESSURE - The pressure of the MANOMETER - A U-shaped tube filled with a saturated vapor at the critical te mperature. liquid that is used to measure the pressure of CRITICAL TEMPERATURE - The temperature gases and vapors. at which the liquid and vapor densities of a MEGOHM - One million ohms. substance become equal.
MULLION HEATER - An electrical heating element used to keep the stationary part (mullion) of the structure between the doors from sweating or frosting. MULTIPLE EVAPORATION SYSTEM - A system with two or more evaporators connected in parallel. MULTIPLE SYSTEM - A system with two or more evaporators connected to one condensing unit. OIL SEPARATOR - A device used to remove oil from a gaseous refrigerant. OZONE - A gaseous form of oxygen, usually generated by a silent electrical discharge in ordinary air. PITOT TUBE - Part of an instrument used to measure air velocities. POTENTIAL ELECTRICAL - The electrical force which tries to move or moves the electrons in a circuit. POTENTIAL RELAY - A relay which is operated by voltage changes in an electromagnet. POWER FACTOR - Correction coefficient for ac power. PYROMETER - A device used to measure high temperatures. RANKIN SCALE (R) - A thermometer scale that is equal to Fahrenheit but using zero as absolute zero instead of -460° F. (absolute Fahrenheit). RELATIVE HUMIDITY - The percent of moisture in the air as to what it can hold at that temperature and pressure. SATURATION - When air is saturated it is holding the maximum amount of water vapor at that temperature and pressure. (It may also be applied to other substances.) SENSIBLE HEAT - Heat that can be measured and causes a change in temperature. SOLAR HEAT - Heat energy waves of the sun.
SPECIFIC GRAVITY - Weight of a liquid compared to water. SPECIFIC HEAT - The ratio of the quantity of heat required to raise the temperature of a body or mass 1° to that required to raise the temperature of an equal mass of water 1°. SPECIFIC VOLUME - Volume per unit (one) mass of a substance. STANDARD ATMOSPHERE - When air is at a condition of 14.7 psia and 68° F. STANDARD CONDITIONS - 68° F., 29.92 inches Hg., and R. H. of 30 percent used in airconditioning calculations. STRATIFICATION OF AIR - When air lies in different temperature layers because of little or no air movement. SUBLIMATION - When a substance changes from a solid directly into a gas without becoming a liquid. SUBCOOLING - Cooling of a liquid below its condensing temperature. SUPERHEAT - Adding heat to a vapor above its boiling temperature and at the same pressure. THERM - 100,000 British thermal units. THERMISTORS - An electrical resistor made of a material whose resistance varies with the temperature. TRANSISTOR - An electrical device used to transfer an electrical signal across a resistor. TRIPLE POINT - A condition of pressure and temperature where the liquid, vapor, and solid states can coexist. VAPOR PRESSURE - The pressure exerted by a vapor upon its liquid or solid form. VELOCIMETER - A direct reading air velocity meter, reading in feet per minute. WEB BULB - A dry bulb thermometer with a wick attached to the bulb that is used in the measurement of relative humidity
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VOCABULARY
Though your definitions of "comfort" may be different than your neighbor’s, knowing these terms can help make your search for improved comfort and efficiency much less confusing and much more effective. —Type of compressor that uses a more efficient process for compressing refrigerant for better cooling efficiency. —Annual Fuel Utilization Efficiency. Indicated as a percentage, your furnace’s AFUE tells you how much energy is being converted to heat. For example, an AFUE of 90 means that 90% of the fuel is being used to warm your home, while the other 10% escapes as exhaust with the combustion gases. —British Thermal Unit. Used for both heating and cooling, BTU is a measure of the heat given off when fuel is combusted. Or for cooling, it’s a measure of heat extracted from your home. One BTU is equal to the heat given off by a wooden kitchen match. —The ability of a heating or cooling system to heat or cool a given amount of space. For heating, this is usually expressed in BTUs. For cooling, it is usually given in tons. —Part of the outdoor portion of a split-system air conditioner or heat pump. By converting refrigerant that is in a gas form back to a liquid, the coil sends heat carried by the refrigerant to the outside. —A type of furnace that takes cool air from the top and blows warm air to the bottom — common where your furnace must be located in a second-floor closet or utility area. —An electronic device that filters out large particles and contaminants in indoor air. It then electronically pulls out tiny particles that have been magnetized, such as viruses and bacteria, drawing them to a collector plate. —A series of studies performed to determine the heating or cooling requirements of your home. An energy load analysis uses information such as the square footage of your home, window or door areas, insulation quality and local climate to determine the heating and cooling capacity needed by your furnace, heat pump or air conditioner. When referring to heating, this is often known as a Heat Loss Analysis, since a home’s heating requi rements are determined by the amount of heat lost through the roof, entry ways and walls. —Part of a split-system air conditioner or heat pump located indoors. The evaporator coil cools and dehumidifies the air by converting liquid refrigerant into a gas, which absorbs the heat from the air. The warmed refrigerant is then carried through a tube to the outdoor unit (condenser coil). —An indoor component of a heat pump system, used in place of a furnace, to provide additional heating on cold days when the heat pump does not provide adequate heating.
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—Term used for Heating, Ventilation, and Air Conditioning —The Heating Seasonal Performance Factor is a measure of the heating efficiency of a heat pump. The higher the HSPF number, the more efficiently the heat pump heats your home. —A type of furnace, installed on its "side," that draws in air from one side, heats it and sends the warm air out the other side. Most often used for installations in attics or crawl spaces. —A piece of equipment that adds water vapor to heated air as it moves out of the furnace. This adds necessary moisture to protect your furnishings and reduce static electricity. —A heating and cooling system comprised of products that have been certified to perform at promised comfort and efficiency levels when used together, and used according to design and engineering specifications. —The day-to-day cost of running your home comfort equipment, based on energy use. —Overall measure of the efficiency and value of your home comfort system. By combining your purchase price and ongoing operating costs, a payback analysis determines the number of years required before monthly energy savings offset the purchase price. ™—The Perfect Heat gas furnaces use a two-stage valve and patented control algorithm allowing the furnace to more closely meet the heating needs of the home. A Perfect Heat heat pump controls the airflow across the indoor coil and controls auxiliary heater banks to deliver warmer, more comfortable air to the home. In both cases the end result is even, consistent heating. ™—Perfect Humidity will remove an amazing amount of moisture from indoor air to help eliminate that warm, sticky, uncomfortable feeling you get in high humidity. Add a humidifier and the system provides Perfect Humidity in heating. —Puron is an environmentally sound refrigerant designed to protect the earth's ozone layer. Federal law r equires all manufacturers phase out ozone depleting refrigerants in the next few years. Puron is approved by the US Environmental Protection Agency as a replacement from Freon 22*. —The Seasonal Energy Efficiency Ratio is a measure of the cooling efficiency of your air conditioner or heat pump. The higher the SEER number, the more efficient the system is at converting electricity into cooling power. —A state-of-the-art electronic thermostat with a built-in memory that can be programmed for different temperature settings at different times of the day. —Refers to an air conditioner or heat pump that has components in two locations. Usually, one part of the system is located inside (evaporator coil) and the other is located outside your home (condenser coil).
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