HomeMy WebLinkAboutB12-0355 Water Heater Sizing APPENDIX D - Wo�ksheet for Calculating Minimum Hot Water Requirements
The following worksheet is provided to assist operators in calculating hot water usage and sizing of
the water heater required for the operation.
I. Calculate Total Water Required By All Fixtures:
A. Three compartment sink calculation of water usage:
1. Measure dimensions, in inches, of each compartment,if compartments are not the same
dimensions see note below.
Length= Width= Depth=
2. Insert measurements into equation
( x x x3x ..375 )=231 =
Length Width Depth Water Usage
Note: If all the compartment sizes of the sink are not the same, then 3 is taken out of the
equation, and the above calculation is done for each compartment. The volumes are added to
obtain the total gallons per hour of hot water used in the sink.
Enter number into the attached"Table to Calculate Total Water Required By All Fixtures,"
found on page Appendix D-4.
B. Utensil soak sink
1. Measure dimensions, in inches, of the sink
Length= Width= Depth=
2. Insert measurements into equation
( x x x .375 )=231 =
Length Width Depth Water Usage
Enter number into the attached"Table to Calculate Total Water Required By All Fixtures,"
found on page Appendix D-4.
Plan Review Packet
D - 1
C. Dishmachine and conveyor pre-rinse water usage:
Use manufacturer's rating in gallons per hour
Enter number into attached"Table to Calculate Total Water Required By All Fixtures."
Clothes washer water usage:
Use manufacturer's rating, or 32 GPH for 9-12 pound washer, or 42 GPH for 16 pound
washer.
Enter number into the attached"Table to Calculate Total Water Required By All Fixtures,"
found on page Appendix D-4.
D. Use the gallon per hour rating for each type of fixture found in the "Table to Calculate Total
Water Required By All Fixtures" and the number of fixtures in the operation to determine
maximum hourly usage far each type of fixture in the operation.
Total water(gph)required by all fixtures:
IL Calculate Maximum Hourly Hot Water Usage
If gas water heater is used go to Step A; if electric, Step B.
A. Gas Water Heater: If a gas water heater is to be used, calculate the maximum hourly hot
water usage for the facility by adjusting the total water required by all fixtures for altitude.
The altitude adjustment is 4%per 1000 feet of elevation, or 20% at 5000 feet.
Use the following equations to determine the maximum hourly hot water usage when a gas
powered water heater is to be used:
(.04 x = 1000)+ 1 =
elevation of facility adjustment factor
X =
adjustment factor total water required maximum hourly
by all fixtures hot water usage
For example, if the total gallon per hour usage for an establishment at an elevation of 5000 feet is
100 GPH, the adjustment factor is 12. Therefore, a water heater with 120 GPH recovery rate would
be required.
Use this value in the equation to calculate the minimum BTU rating of the water heater.
B. Electric Water Heater: If an electric water heater is to be used, the maximum hourly usage
for the operation is the same as the total water required by all fixtures. Use this value in the
equation to calculate the minimum Kilowatt rating of the water heater.
Plan Review Packet
D -2
C. Insert the value determined in step A or B above in III D (3),Appendix C,Plan Review
Form,Page Appendix C-6. This value is the minimum recovery rate of the water heater
which should be provided for the facility.
III. Calculate the minimum BTU or Kilowatt rating of water heater:
A. For gas water heater, calculate the minimum BTU rating:
(Max hourl_y usage as calculated above)x (100)x(833�=minimum BTU rating
.75 or use manufacturer's thermal efficiency
B. For electric water heater, calculate the minimum Kilowatt rating :
(Max hourly usage as calculated above)x(100)x(833�=minimum Kilowatt rating
3412
C. Select water heater based upon BTU ar Kilowatt rating.
Make: ; Model#:
BTU or Kilowatt Rating:
Recovery rate: gallons per hour at 100°F rise at sea level.
Plan Review Packet
D - 3
Table to Calculate Total Water Required By All Fixtures.
Water Usage Number of Maximum hourly water
Plumbing Fixture usage per type of�xture
(gallons per hour) fixtures (gallons per hour)
example: warewashing 50 1 50
machine
example: handsink(s) 5 4 (5 x 4 =) 20
3-compartment sink
3-compartment sink(bar)
utensils soak sink
warewashing machine
warewashing machine
conveyor pre-rinse
clothes washer
hand operated pre-rinse 32
sprayer
handsink(s), include rest 5
rooms
mop sink 7
garbage can washer 35
showers 14
hose bibb used for 35
cleaning
Total water(gph) required by all fixtures
Plan Review Packet
D -4