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SECTION F: DOMESTIC HOT WATER PIPING
When designing the water piping system for domestic water applications, water hardness should be considered. Table F-1
indicates the suggested flow rates for soft, medium and hard water. Hardness is specified as grains per gallon.
TABLE F-1
DOMESTIC WATER HEATER
FLOW RATE REQUIREMENTS
DT = Temperature rise, degrees F DP = Pressure drop, ft, through heat exchanger SHL = System head loss, ft.
GPM = Gallons/minute, flow rate MPS = Minimum pipe size, NPT
System head loss based on heater and tank placed no more than 5 ft. apart and equivalent length pipe/fittings as follows:
2” NPT = 75 ft.
* Must use optional cupronickel tubes.
POTABLE WATER AND SPACE HEATING APPLICATION
CAUTION: When this heater is used for both -potable water and space heating- follow the steps below
to insure proper operation.
A. All piping materials and components connected to the water heater for the space heating application
shall be suitable for use with potable water.
B. Toxic chemicals, such as used for boiler treatment, shall not be introduced into the potable water used
for space heating.
C. If the water heater will be used to supply potable water, it shall not be connected to any heating system
or components previously used with a nonpotable water heating appliance.
D. When the system requires water for space heating at temperatures higher than 140°F, a means such as a
mixing valve shall be installed to temper the water in order to reduce scald hazard potential.
SINGLE DOMESTIC HOT WATER HEATER WITH ONE STORAGE TANK
16
Fig. #9224.1
City Water
System Retu
rn
Hot Water Supply