American Water Heater DCG - Manual (Page 12)

12
Figure 8: Commercial Unit with Auxiliary Storage Heater - Forced Circulation
With or Without Building Recirculation - Top Inlet/Outlet Connections
Closed System/Thermal Expansion
Periodic discharge of the temperature and pressure
relief valve may be due to thermal expansion in a
closed water supply system. The water utility supply
meter may contain a check valve, backflow preventer or
water pressure reducing valve. This will create a closed
water system. During the heating cycle of the water
heater, the water expands causing pressure inside the
water heater to increase. This may cause the
temperature and pressure relief valve to discharge
small quantities of hot water. To prevent this, it is
recommended that a diaphragm-type expansion tank
(suitable for potable water) be installed on the cold
water supply line. The expansion tank must be properly
sized for the application. Contact the local water suppli-
er or plumbing inspector for information on other meth-
ods to control this situation.
Important: Do not plug or remove the temperature
and pressure relief valve.
Please note the following:
DO NOT install this water heater with iron piping. The
system should be installed only with piping that is suit-
able for potable (drinkable) water such as copper,
CPVC, or polybutylene. DO NOT use PVC water piping.
DO NOT use any pumps, valves, or fittings that are not
compatible with potable water.
DO NOT use valves that may cause excessive restric-
tion to water flow. Use full flow ball or gate valves only.
DO NOT use 50/50 tin-lead solder (or any lead based
solder) in potable water lines. Use 95/5 tin-antimony or
other equivalent material.
DO NOT tamper with the gas valve/thermostat, igniter,
or temperature and pressure relief valve. Tampering
voids all warranties. Only qualified service technicians
should service these components.
DO NOT use with piping that has been treated with
chromates, boiler seal, or other chemicals.
DO NOT add any chemicals to the system piping which
will contaminate the potable water supply.
1 1/2” Cold
water supply
Pressure
Reducing
Valve
Thermometer
Temperature and
Pressure Relief Valve
Hot Water
to Fixtures
Pre-Heater
Pre-Heated
Water to
the Booster
Outlet
Boosted
Temperature
Temperature and
Pressure Relief Valve
Typical
Booster
Heater
Shut-off valve
Thermometer
Thermal
Expansion
Tank
Shut-off
valve
Check valve
Note: Install a vacuum
relief valve if required
by local codes.
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