A.H.U / Fan Room (p1 of 2)
M1
(approx. sizing using rules of thumb) ARE32OL Design 2 Museum / Classroom Project H.V.A.C. Preliminary Design
STEP 1 Determine air flow req'd for each space, for total size of fan unit(s) in tons. Equation: Area (program) / (sf/ton) = tons req'd for space Classroom
8100sf
Museum
8100
Office Lobby
/
350sf/ton
=
/
Classroom
8100sf
450
18
Museum
8100
450
18
1100
400
2.75
Office
1100
400
2.75
2700
350
7.7
Lobby
2700
350
15.4
(Note: not including Freight for now)
This could be adequate for a Lobby that is less than 50% glass
350sf/ton
=
23.2 tons
Assuming that the Lobby is mostly glass, and exposed on 3 sides, we will DOUBLE the air requirement in the Lobby...
23.2 tons
59.35 tons
TOTAL Bldg. Cooling Load:
60 TONS Discuss: - Methods of approximating / rough-sizing. Final design process much more involved. - What is a "ton" in HVAC. - Where do these numbers come from (sf/ton by use). - 10 cfm/person outside air included in numbers.
Quick check: Overall Area / Tons = ? 20,000 / 60 = 333.3
A.H.U / Fan Room (p2 of 2)
M2
(approx. sizing using rules of thumb) ARE32OL Design 2 Museum / Classroom Project H.V.A.C. Preliminary Design
STEP 2 Size the fan unit by approximating the size of the coil. o
T, use 400 cfm/ton (rule of thumb) for air capacity: A. For 20 Calculate: 60 tons x 400 cfm/ton = 24,000 cfm B. Use (rule of thumb) 500 ft./min. for air speed at coil: Calculate: 24,000 cfm / 500 ft/min. = 48 sf SIZE OF COIL = Hdim x Wdim of A.H.U. = 48
SF
LENGTH OF A.H.U. = ~ 2 x COIL SIZE 1 unit:
48 sf =
2 units: (2) at
6.9' .... use 1 unit with 7' x 7' coil x 14'L 24 sf = 4.9' .... use 2 units with 5' x 5' coil ea. x 10'L
3 units: (3) at 16 sf = 4' .... use 3 units with 4' x 4' coil ea. x 8'L Discuss: - Delta T for Austin: 75F to 55F - Speed at air coil. - Machine access / maintenance.
STEP 3
1 unit option:
24sf = 4.9' .... use 5' x 5' duct (big!)
2 unit option: 12sf ea. = 3.46' .... use 3.5' x 3.5' duct ea. 3 unit option: 8sf ea. = 2.83 .... use 3' x 3' duct ea. NOTE: Main Duct dimension can vary up to 2:1 ratio in section.
min.
min.
From Step 2: 24,000 cfm / 1000 ft/min = 24sf coil area
coil
coil width
A. Max. velocity for forced air = 1,000 ft/min.
~ 4'
Size the coil area and initial supply duct: coil min.
2 x coil width A.H.U.
Fan Room - Preliminary Design Plan Size
Boiler / Boiler Room (p1 of 2)
M3
(approx. sizing using rules of thumb) ARE32OL Design 2 Museum / Classroom Project H.V.A.C. Preliminary Design
Single-unit design: Determine heat req'd for each space, for total heat in btu's.
x
28 btu/sf
=
Classroom
8100sf
Museum
8100
24
194,400
Office
1100
25
27,500
Lobby
2700
35
94,500
4'-0" min.
for shallow, wide unit:
Equation: Area (program) / (btu/sf)5 = heat req'd for space 4'-0"
226,800 btu
min.
Boiler
4'-0"
Pumps 4'-0"
min.
min.
Boiler Room - Preliminary Design Plan Size
TOTAL HEAT:
Discuss: - BTU values for spaces by use (typ. range 24 - 30). - Units (sizing boiler): 1 mbh = 1000btu - If > 400,00 btu = "boiler" = required 1-hour rated enclosure, and periodic inspections. - If < 200,000 btu = "hot water heater"
divide by 1,000 = ~ 543 mbh unit needed.
Example: HydroTherm ID-85A Boiler 500 mbh 1'-6"W 3'-6"L 2'-6"H
Lochinvar 750 btu/hr unit: (Revit module for class) 2'-0"W, 2'-4"L, 4'-4"H for deep unit:
Boiler ?
4'-0" min.
543,200 BTU
Pumps
4'-0"
4'-0"
4'-0"
min.
min.
min.
Boiler Room - Preliminary Design Plan Size
Boiler / Boiler Room (p2 of 2)
M4
(approx. sizing using rules of thumb) ARE32OL Design 2 Museum / Classroom Project H.V.A.C. Preliminary Design
Multiple-unit design: Total btu reqd. = 543,000 3 units under 199btu has advantages. Lochinvar mfg. 1 unit option: 1 at 500 btu, or 2 unit option: 2 at 300 btu ea., or 3 units option: 3 at 165 btu ea. (199 btu and under = hot water heater status)
4'-0" min.
2'-0" Clear, typ.
3 water heaters
Manuf: Lochinvar 4'-4"H, 2'-4"L, 2'W
Water Heater Room - Preliminary Design Plan Size + 2 pumps in adjacent Chiller Room
Chiller / Chiller Room
M5
(approx. sizing using rules of thumb) ARE32OL Design 2 Museum / Classroom Project H.V.A.C. Preliminary Design
STEP 1 Determine efficiency / life-span of unit: Least efficient
Most efficient
York chiller, 118 tons
10 - 12 year life
DX system
$3200/ton
25 year life
air-cooled system
$4800/ton
35 year life
water-cooled system
$6800/ton
(Source: S.Allen, rules of thumb based on project histories) Typically, building will have an air-cooled system if below 300 tons. Water is better (more efficient, longer life-span), typical on big commercial systems over 300 tons.
5'-0"
STEP 2
Bell & Gosett PUMPS: 1'-5"W, 4'-7"L, 1'-9"H Each (2) HW (2) CW (2) condensor
Choose unit.
4'-0"
60 ton req'd, min. size water unit is 100 ton (oversized, but fine) York manufacturer, 100 ton unit: 138" L (11'-6) 44" W (3'-8) 73" H
Chiller: McQuay Int. 6'-2"W, 11'-8"L, 8'H
Plan for Tube replacement
Discuss: - Difference between 3 systems: how they work.
4'-0"
Chiller
Chiller Room Plan Preliminary Design Size
4'-0"
Cooling Tower + Enclosure
M6
(approx. sizing using rules of thumb) ARE32OL Design 2 Museum / Classroom Project H.V.A.C. Preliminary Design
Choose unit based on # tons required. For our project, 60 ton req'd, min. size unit is 100 ton. This oversized, but fine as most units run best at about 75% capacity). Manuf: Marley, 100 ton unit: 12' L 4' D 10' H Min. clear around cooling tower: 6' for small units. More clearance for larger units.
Cooling Tower
8'-0" Typ. clearance all around + must be open to sky.
Cooling Tower: Morley 12'-10"L, 10'-7"W, 10'-2"H
Cooling Tower Enclosure - Preliminary Design Plan Note: THIS UNIT IS OUTSIDE (ROOF OR GROUND LEVEL) Discuss: 2 How cooling towers work, types of systems, vibration and weight.
Note: Revit files and product pdf: http://seek.autodesk.com/product/latest/agg/spxcoolingtechnologies/SPX-Cooling-Technologies/SPX0001
Electrical and Other Service Rooms
M7
(approx. sizing using rules of thumb) ARE32OL Design 2 Museum / Classroom Project H.V.A.C. Preliminary Design
OUTSIDE DOOR
10'-0"
MIN.
Main Electrical Room
Water Service + Fire Protection Room
ELECTRICAL TRANSFORMER: 6'W X 6'L X 6'H
8'-0" MIN.
Pump(s)
MIN.
3'x3' PAD (METER)
8'-0"
10'-0" CONC. PAD
4'-0"
1'-0"
MIN.
MIN.
CITY ELECT SERVICE: 12,000 VOLTS STEP DOWN 1ST OUTSIDE, THEN AGAIN INSIDE MAIN ELECT. RM.
10'-0"
MIN.
ELEC. PANELS, SECURITY, TEL, A.V.
5'-0" MIN.
10'-0"
10'-0"
MIN.
10'-0"
ELECTRICAL TRANSFORMER: 3'W X 3'L X 5'H
PANELS
OUTSIDE DOOR
Secondary Elec. Room
For Hydraulic elevators (70' max lift): Locate machine room near bottom landing. (hydraulic fluid pumps and panels) For Electric elevators: Locate machine room at roof above top of cab. (electric motorized hoist and panels)
Hydraulic Elev. Machine Room OUSTIDE PAD-MOUNTED ELEC. TRANSFORMER
I.T. Room:
Many buildings will have one I.T. Room per floor (8'x10') with it's own DX cooling system (for internet servers).
