ahu room size.pdf

(1)

Assuming that the Lobby is mostly glass, and exposed on 3 sides, we will DOUBLE the air requirement in the Lobby...

TOTAL Bldg. Cooling Load:

60 TONS

Quick check:

Overall Area / Tons = ? 20,000 / 60 = 333.3

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 Museum Office Lobby

(Note: not including Freight for now) 8100sf 8100 1100 2700 350sf/ton 450 400 350 / 23.2 tons 18 2.75 7.7 = Classroom Museum Office Lobby 8100sf 8100 1100 2700 350sf/ton 450 400 350 / 23.2 tons 18 2.75 15.4 = This could be adequate for a Lobby that is less than 50% glass

59.35 tons

ARE32OL Design 2 Museum / Classroom Project H.V.A.C. Preliminary Design

M1

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.

A.H.U / Fan Room (p1 of 2)

(2)

M2

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 = 6.9' .... use 1 unit with 7' x 7' coil x 14'L

2 units: (2) at 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

Size the coil area and initial supply duct: A. Max. velocity for forced air = 1,000 ft/min.

From Step 2: 24,000 cfm / 1000 ft/min = 24sf coil area 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.

A.H.U / Fan Room (p2 of 2)

(approx. sizing using rules of thumb)

2 x coil width co il w id th ~ 4 ' _coil coil

Fan Room - Preliminary Design Plan Size A.H.U. m in . min. min.

(3)

Single-unit design:

Determine heat req'd for each space, for total heat in btu's. Equation: Area (program) / (btu/sf) = heat req'd for space5

TOTAL HEAT:

543,200 BTU

Classroom Museum Office Lobby 8100sf 8100 1100 2700 28 btu/sf 24 25 35 x 226,800 btu 194,400 27,500 94,500 = ARE32OL Design 2 Museum / Classroom Project H.V.A.C. Preliminary Design

M3

Boiler / Boiler Room (p1 of 2)

(approx. sizing using rules of thumb)

?

Example:

HydroTherm ID-85A Boiler 500 mbh

1'-6"W 3'-6"L 2'-6"H

divide by 1,000 = ~ 543 mbh unit needed.

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"

Lochinvar 750 btu/hr unit: (Revit module for class) 2'-0"W, 2'-4"L, 4'-4"H

Boiler Room - Preliminary Design Plan Size Boiler

4'

-0

" _Pumps

for shallow, wide unit:

4'-0" min. 4'-0" min. 4'-0" min. m in .

Boiler Room - Preliminary Design Plan Size Boiler _4'-0"

m

in

.

Pumps for deep unit:

4'-0" min. 4'-0" min. 4'-0" min.

(4)

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)

M4

Boiler / Boiler Room (p2 of 2)

(approx. sizing using rules of thumb)

Water Heater Room - Preliminary Design Plan Size 3 water heaters

+ 2 pumps in adjacent Chiller Room

4' -0 " m in . 2'-0" Clear, typ. Manuf: Lochinvar 4'-4"H, 2'-4"L, 2'W

(5)

STEP 1

Determine efficiency / life-span of unit:

Least efficient 10 - 12 year life DX system $3200/ton

25 year life air-cooled system $4800/ton

Most efficient 35 year life water-cooled system $6800/ton

(Source: S.Allen, rules of thumb based on project histories)

M5

Chiller / Chiller Room

(approx. sizing using rules of thumb)

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.

STEP 2

Choose unit.

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

Discuss:

- Difference between 3 systems: how they work.

York chiller, 118 tons

Chiller Room Plan - Preliminary Design Size

Chiller 4' -0 " 4' -0 " 4'-0" Plan for Tube replacement 5' -0 " PUMPS: (2) HW (2) CW (2) condensor

Bell & Gosett

1'-5"W, 4'-7"L, 1'-9"H Each

Chiller: McQuay Int. 6'-2"W, 11'-8"L, 8'H

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M6

Cooling Tower + Enclosure

(approx. sizing using rules of thumb)

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

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

Cooling Tower Enclosure - Preliminary Design Plan

Note: THIS UNIT IS

OUTSIDE

(ROOF OR GROUND LEVEL)

Cooling Tower 8'-0" Typ. clearance all around + must be open to sky. Min. clear around

cooling tower: 6' for small units. More clearance for larger units.

Cooling Tower: Morley 12'-10"L, 10'-7"W, 10'-2"H

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M7

Electrical and Other Service Rooms

(approx. sizing using rules of thumb)

10'-0" 10 '-0 " ELECTRICAL TRANSFORMER: 3'W X 3'L X 5'H OUTSIDE DOOR

Main Electrical Room

ELEC. PANELS, SECURITY, TEL, A.V.

CITY ELECT SERVICE: 12,000 VOLTS STEP DOWN 1ST OUTSIDE, THEN AGAIN INSIDE MAIN ELECT. RM.

M IN . MIN. 10'-0" 10 '-0 " ELECTRICAL TRANSFORMER: 6'W X 6'L X 6'H

OUSTIDE PAD-MOUNTED

ELEC. TRANSFORMER

3'x3' PAD (METER) CONC. PAD 10'-0" 10 '-0 " OUTSIDE DOOR

Water Service +

Fire Protection Room

MIN. M IN . 4'-0"

Secondary

Elec. Room

1'-0" P A N E LS 5' -0 " M IN .

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). 8'-0" 8' -0 "

Hydraulic Elev.

Machine Room

P um p (s ) M IN . MIN.

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)