9
2- PIPING THE COMBINATION HEATER
A-Thermal Expansion
If a backflow preventer, check valve or
pressure reducing valve is piped on cold
water inlet, install an expansion tank on
cold water supply line to prevent nor-
mal thermal expansion from repeatedly
forcing open T&P relief valve.
T&P relief valve is not intended for
constant duty, such as relief of pressure
due to repeated normal system expan-
sion. Correct this condition by
installing a properly sized expansion
tank in domestic water system. Refer
to expansion tank manufacturer’s
instructions for proper sizing.
B- Air Vent
•
Automatic air vent is factory installed on
the heater.
•
Unscrew vent cap on air vent one full
turn. Leave cap unscrewed one turn
for normal venting.
C- Temperature and Pressure Relief
Valve
•
T&P relief valve is factory installed on
inner tank of the heater.
•
T&P relief valve per AGA of 100,000
Btu/hr for G-25.
•
T&P relief valve rated per AGA of
200,000 Btu/hr for G-30.
•
T&P relief valve discharge piping must be:
- made of material serviceable for
temperatures of 250ºF or greater
- directed so that hot water flows
away from all persons.
- directed to a suitable place for
disposal.
- installed so as to allow complete
draining of the T&P relief valve and
discharge line.
•
T&P relief valve discharge piping must
not be:
- excessively long. Using more than 2
elbows or 15 feet of piping can
reduce discharge capacity.
- directly connected to a drain.
Terminate discharge piping within
6” from floor. Refer to local codes.
- plugged, reduced or restricted.
- subjected to freezing.
Do not install any valve between T&P relief
valve and tank connection, or on T&P
relief valve discharge piping. Do not plug
T&P relief valve or discharge piping.
Improper placement and piping of T&P
relief valve can cause severe personal
injury, death or substantial property dam-
age.
D- Pressure Relief Valve
•
Pressure relief valve is factory installed
on outer tank of the heater.
•
30 psig pressure relief valve rated per
AGA of 535,000 Btu/hr.
•
Provide safe discharge through piping
near floor or close to floor drain. Relief
valve must be installed so that the spindle
is vertical.
To avoid scalding or water damage,
relief valve discharge must be piped near
floor or close to floor drain. Do not plug,
valve or place any obstruction in dis-
charge piping.
3. WATER HAMMER
Dishwashers, clothes washers and fast-clos-
ing positive shut-off valves incorporated in
the system all contribute to creating water
shock. Install a water hammer arrester to pre-
vent damage to pipes and appliances. See
manufacturer’s instructions for application
and installation.
WARNING
WARNING
CAUTION
INSTALLATION