HVAC Thumprule Handbook

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Thumb rules for HVAC design

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HEAT LOAD DETAILS

1. DBT, WBT, RH and daily range from ISHRAE handbook P. No – 1.1 to 1.3

Outside Conditions Month DBT WBT RH GR/LB

BangaloreSummer April 96 78 45 116Monsoon September 82 78 82 140Winter January 58 54 78 56

ChennaiSummer May 103 82 41 132Monsoon November 83 80 88 152Winter January 65 57 60 58

MumbaiSummer April 95 83 60 151Monsoon July 85 82 88 162Winter January 65 58 65 60

HyderabadSummer May 106 78 28 100Monsoon September 85 81 82 154

Winter December 55 48 60 39

New DelhiSummer May 110 75 20 75.81Monsoon Aug 95 83 60 154.37Winter January 45 41 70 31.93

Kolkatta

Summer May 100 83 49 144Monsoon July 90 83 85 161

Winter December 56 48 55 37

2. Eq. temp diff for wall (∆T F) = 4 PM eq. temp value (ISHRAE handbook table 9 in P. No – 1.14) +

correction to eq. temp (Table 11P. No – 1.15)

3. Q wall(BTU/Hr) = U x A x ∆T 1

4.

Solar heat gain through glass (BTU/Hr Sft) = 4 PM value (ISHRAE handbook table 7 in P. No – 1.8

to 1.10)

5. QGlass(BTU/Hr) = (U x A x ∆T) + (SHG x A x SF) where (∆T = OA Temp – IA Temp)

6. Fresh air CFM can be derived with the sample sheet attached (ASHRAE Ventilation Standard

62_1_2004 Table 6.1)

7. Fresh Air CFM = (Volume x ACPH) / 60

8. Sensible Fresh air infiltration load = Fresh Air CFM x ∆T x 1.08 x Coil BF (ISHRAE handbook

table 14 in P. No – 1.16)

9.

Latent Fresh air infiltration load = Fresh Air CFM x ∆G x 0.68 x Coil BF (ISHRAE handbook table14 in P. No – 1.16)

10. Typical bypass factors - Three Row coil BF=0.176 (17.6 %), Four Row coil BF=0.12 (12 %), Six

Row coil BF=0.06 (6%)

11. Optimum velocity of air through coil is 450 fpm

12. HRW ηηηη = (OSA Temp – Temp after HRW) / (OSA Temp – Return Air Temp)

13. Sensible lighting load = W/sft x Area


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6. Various types of camera were used for monitoring as per the requirement for 24 x 365. Namely

Fixed dome, Varifocal, PTZ(Pan Tilt Zoom) Camera.

7.

CCTV also can be linked with FPCP in modern system to know exactly how the fire or smokecondition.

Public addressable system

1. Also a security system runs all the floors and parking’s and used for announcements etc….

2. Systems consist of various models of speakers, amplifiers and micro phones.

3. System can be integrated with FACP and CCTV

4. Three type of speaker namely ceiling mounted, wall mounted, horn speaker can be used.

Access Control System

1. Smart card reader, Proximity card reader or Biometric card reader can be used. Biometric can be

retina or finger print reader

2. From card reader signal is sent to controller, which can be connected to software for monitoring

and for report generation using access control software.

3. Controllers to PC cat 5 cables are used. Controller to reader / push button 4c x 0.75 sq mm cable

is used

Building Management System

1. Field devices are connected to DDC (Digital Direct Controller), which has digital or analog input

and output. Analog input is for sensors and digital input is for switches.

2. DDC can be 16 or 32 bits. Various inputs are connected to it. It acts as a interface and converts

them into binary language which a system can understand.

3. This is then transferred to Router using RS 485 cable, which is then connected to PC using RS

232 cable.

This also provides facility for third party integration such as electrical, plumbing, DG, energy meter, ups, VFD etc .

SITE ACTIVITIES

1. Duct size as per dwg

2. Duct supports for every 8 to 10 feet

3. Duct to duct flange gap should be arrested properly


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P a r t i c u l a r s

N O R T H

S O U T H

E A S T

W E S T

N E

S E

S

N W

B A N G A L O R E

S u m m e

r

S o l a r H e a t G a i n T h

r o u g h G l a s s ( B T U / H r S f t )

3 9

1 1

1 1

1 6 3

1 1

1 1

9 4

1 3 0

M o n s o

o n

1 1

1 3

1 1

1 6 4

1 1

1 1

1 2 7

1 0 3

W i n t e r

9 6 5 9

1 4 3

9 9 1 5 3

3 7

C H E N N A

I S u m m e

r 3 9

1 1

1 1

1 6 3

1 1

1 1

9 4

1 3 0

M o n s o o n

1 1

1 3

1 1

1 6 4

1 1

1 1

1 2 7

1 0 3

W i n t e r

9 6 5 9

1 4 3

9 9 1 5 3

3 7

M U M B A I S

u m m e

r 1 1

1 1

1 1

1 6 5

1 1

1 1

1 1 3

1 1 8

M o n s o

o n

1 1

2 2

1 1

1 6 3

1 1

1 1

1 3 6

8 7

W i n t e r

8 6 9 8

1 2 8

8 8 1 4 4

2 6

H Y D R A B A D

S u m m e r 1

1 1 1

1 1

1 6 5

1 1

1 1

1 1 3

1 1 8

M o n s o

o n

1 1

2 2

1 1

1 6 3

1 1

1 1

1 3 6

8 7

W i n t e

r 8 6 9 8

1 2 8

8 8 1 4 4

2 6

N e w D e l h i S

u m m e r 1

4 1 2

1 2

1 6 4

1 2

1 2

1 0 0

1 2 3

M o n s o

o n

1 1

1 3

1 1

1 6 5

1 1

1 1

1 2 7

1 0 0

W i n t e r

6 6 8 6 1 0 9 6 6 1 2 7 1 6

K o l k a t t a

S u m e r 2

3 1 2

1 2

1 6 3

1 2

1 2

8 5

1 3 8

M o n s o

o n

2 3

1 2

1 2

1 6 3

1 2

1 2

8 5

1 3 8

W i n t

e r 7 7 4 7

1 1 8

7 7 1 3 9

1 8


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40 sq.ft/person for Corridors in other floors & Hypermarket

Lighting :

5 Watts/sq.ft for Shops, Hypermarket

3 Watts/sq.ft for Common areas, Foodcourt,Café, Restaurant

1 Watts/sq.ft for Theatres & Projector rooms.

Equipment load :

1 Watts/sq.ft for Shops

1.2 Watts/sq.ft for Café, Restaurant, Foodcourt

2 Watts/sq.ft for Anchor Shops & Departmental store

3.7 Watts/sq.ft for Hypermarket

10 kW/projector

Fresh Air CFM :

15 cfm/person for Hypermarket & Theatres

1 ACPH for others

1200 cfm/projector for Projector room

Hotels :

Occupancy :

- 2 person/room

- 25 sq.ft/person - for Dining rooms, Training Rooms, GYM, SPA & Business Center

- 12 sq.ft/person - for Banquet Hall & Pre function & Bar.

- 100 sq.ft/person - for Corridor.

Lighting :

1.5 Watts/sq.ft

Equipment :

- 1.2 Watts/sq.ft for Coffee shop&Gym

- 5 kW for Banquet hall

- 3 kW for Pre function

- 150 Watts/Computer for Offices

Fresh Air CFM :

25 cfm/person - for Rooms,GYM


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11. Human comfort chart

ELECTRICAL

1. For electrical load calculation – Lighting 1.5 W/sft, Power load – 0.75 W/sft, Socket power (5 A)

-100 W and for 15A – 500 W


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21 20 2 3 24 21 23 27 1 2525 20 49 3 16 25 23 25 2 1729 21 30 2 51 29 23 17 3 7

DeclinationEquationof time Declination

Equationof time

Date Deg Min Min Sec Date Deg Min Min SecJuly 1 23 10 -3 31 Aug 1 18 14 -6 17

5 22 52 4 16 5 17 12 5 599 22 28 4 56 9 16 6 5 33

13 21 57 5 30 13 14 55 4 5717 21 21 5 57 17 13 41 4 1221 20 38 6 15 21 12 23 3 1925 19 50 6 24 25 11 2 2 1829 18 57 6 23 29 9 39 1 10

Declination Equationof time Declination Equationof timeDate Deg Min Min Sec Date Deg Min Min SecSep 1 8 35 0 15 Oct 1 -2 53 10 1

5 7 7 1 2 5 4 26 11 179 5 37 2 22 9 5 58 12 27

13 4 6 3 45 13 7 29 13 3017 2 34 5 10 17 8 58 14 2521 1 1 6 35 21 10 25 15 1025 0 32 8 0 25 11 50 15 4629 2 6 9 22 29 13 12 16 10

Declination

Equation

of time Declination

Equation

of timeDate Deg Min Min Sec Date Deg Min Min Sec Nov 1 -14 11 16 21 Dec 1 -21 41 11 16

5 15 27 16 23 5 22 46 9 439 16 38 16 12 9 22 45 8 1

13 17 45 15 47 13 23 6 6 1217 18 48 15 10 17 23 20 4 4721 19 45 14 18 21 23 26 2 1925 20 36 13 15 25 23 25 0 2029 21 21 11 59 29 23 17 -1 39

5. The position of the sun is generally given as azimuth and altitude angle

6.

Azimuth represents horizontal angle of the sun relative to the north.

7. Altitude represents the vertical angle the sun makes with the horizontal ground plane.


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SHAFT SIZING

1. Pipe sizing can be done both using Chart and formula.

2.

Pipe dia (mm) = Sqrt (Gpm x 0.000011) x 2000 for 6 fps velocity3. Pipe dia can be calculated using ∆P = (4 x f x L x V2) / 2 x g x D, Where f is the friction

factor, L is the Equivalent Length, g is the acceleration due to gravity 9.8 m/s2 and V is the

velocity in m/s

4. Pipes going outside the building, Underground and diameter greater than 350mm should be

provided the insulation thickness of 3”. Others should be insulated by 2”.

5. For example, if the pipe dia is 14”, shaft size required will be 14”+6”(insulation on pipe

dia)=20” (supply) + 20” (return) + 18”(Space in between). So shaft length will

be(6”+20’+6”+20”+6”)=58”. (20”+6”+6” )= 32” will be the width of the shaftAHU SIZING

1. Select AHU Size for the given CFM & TR

2. Provide 1.5m space in piping side and 1m space in filter side. Minimum of 150mm in all

other sides.

3. CFM = Velocity x Area

4. Coil face velocity is limited to 500 FPM

VENTILATION AIR CHANGES

1.

Toilet, Electrical – 15ACPH

2. Basement – 6 ACPH (normal) 30 (Fire mode)

3.

Kitchen – 45 to 60 for big – 15 for small 15 ACPH is sufficient

4. Fresh air has to be supplied at 80% of exhaust air in order to maintain negative pressure

5.

For kitchen hood exhaust, CFM = Hood Area x 120 fpm. 80% of exhaust will be ducted as

a fresh air into the kitchen


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2. Primary pump head = Pipe eq. length till secondary pump + primary pump outlet valves +

chiller evaporator valves + secondary pump inlet valves + evaporator pressure drop

3.

Secondary pump head = pipe length till farthest AHU + AHU coil pressure drop + AHUvalves + Secondary pump outlet valves + Pipe length till Primary pump + Primary pump

inlet valves

4. Condenser pump head = Pipe length till cooling tower + Nozzle pressure loss + clearance

height + chiller condenser + condenser pump valves + Chiller condenser side valves

5. Valve Losses

Isolation Valve Balancing/ 2way valve NRV Y Strainer

Diameter EquivalentLength Diameter EquivalentLength Diameter EquivalentLength Diameter EquivalentLength25 29 25 15 25 10 25 1032 38 32 20 32 14 32 1440 43 40 24 40 16 40 1650 55 50 30 50 20 50 2065 69 65 35 65 25 65 2580 84 80 43 80 30 80 30100 100 100 50 100 35 100 35125 120 125 58 125 40 125 40150 140 150 71 150 50 150 50200 170 200 88 200 60 200 60

250 220 250 115 250 80 250 80300 280 300 145 300 100 300 100350 320 350 165 350 120 350 120400 360 400 185 400 135 400 135450 410 450 210 450 150 450 150500 460 500 240 500 165 500 165550 520 550 275 550 200 550 200600 610 600 320 600 240 600 240

6. Closed circuit friction loss


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LIGHTING LOAD TO BE CONSIDERED AS PER ECBC

ELECTRICAL LOAD

1. Air cooled chiller – 1.3KW/TR

2.

Water cooled centrifugal chiller – 0.65KW/TR, Water cooled screw chiller – 0.75 Kw/TR

3. Primary Pump = TR x GPM x Head x 0.745

3960 x Efficiency

4. AHU = CFM x Static x 0.745

6356 x Fan Efficiency

5.

Cooling tower = TR x 300 x 1x 0.745


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PUMP HEAD CALCULATION

1. Pipe friction can be calculated from the chart below


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11. Where hv = (V / 4005) ^ 2


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6356 x 0.6

=TR x 0.117

6. Split AC, Ductable split, Package unit = 1.2KW/TR

7. Ventilation (inlet fan) = Vent.Cfm x 1.2 x 0.745

6356 x 0.6

8. Kitchen (supply) = Vent.Cfm x 1.5 x 0.745

6356 x 0.6

9. Kitchen (exhaust) = Vent.Cfm x 4 x 0.745

6356 x 0.6

GENERAL APPLIANCES LOAD


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DUCT STATIC PRESSURE CALCULATION

1. Filter pressure drop can be calculated from the table below

2. Coil side pressure drop can be calculated from the table

3. Volume Control Damper – 7.5 mm

4.

Grill – 2.5 mm

5. Silencer – Max allowable pre drop is 7.5 mm

6. Diffuser – 2.5 mm

7. Nozzle – From catalogue


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8. VAV – 2 mm

9. Duct pressure from the chart below or using duct sizer

10. Equivalent bend length and taper length can be calculated from the chart below


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HVAC Thumprule Handbook

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