GSW 72090 - Manual (Page 12)

Important: Always use a good grade of joint compound,
approved for use with potable water systems, and be certain
that all fittings are drawn up tight.
Important: Some models may contain energy saving heat
traps to prevent the circulation of hot water within the pipes.
Do not remove, modify or tamper with the heat traps or any
inserts within the heat traps.
Please note the following:
DO NOT install this water heater with iron piping. The sys-
tem should be installed only with new piping that is suitable
for potable (drinkable) water such as copper, CPVC or poly-
butylene. DO NOT use PVC water piping.
DO NOT use any pumps, valves or fittings that are not com-
patible with potable water.
DO NOT use valves that may cause excessive restriction to
water flow. Use full flow ball or gate valves only.
DO NOT use any lead based solder in potable water lines.
Use appropriate tin-antimony or other equivalent material.
DO NOT use with piping that has been treated with chro-
mates, boiler seal or other chemicals.
DO NOT add any chemicals to the system piping that will
contaminate the potable water supply.
Closed System/Thermal Expansion
Periodic discharge from 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. 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 dis-
charge small quantities of hot water. To prevent this from
happening, there are two recommendations:
1. Install a diaphragm-type expansion tank that is suitable
for potable water on the cold water supply line. The
expansion tank must have a minimum capacity of 5.7
litres (1.5 US gallons) for every 190 litres (50 US gal-
lons) of stored water and be rated for 150 psi or the
working pressure of the water heater.
2. Install a pressure relief valve rated at max 125 psi in the
cold water supply line. Make sure the discharge of this
valve is directed to an open drain and protected from
freezing. Contact the local water supplier or plumbing
inspector for information on how to control this situation.
Important: Do not plug the temperature and pressure relief
valve.
Temperature and Pressure (T&P) Relief
Valve
Refer to Figure 12 for a typical T&P valve installation.
Important: Only a new temperature and pressure relief
valve should be used with your water heater. Do not use an
old or existing valve as it may be damaged or not adequate
for the working pressure of the new water heater. Do not
place any valve between the relief valve and the tank.
Figure 11 Typical Tempering Valve Installation
TEMPERING
VALVE (SET TO
49°C (120°F))
FOLLOW THE TEMPERING
VALVE MANUFACTURER'S
INSTRUCTIONS
COLD WATER INLET
PIPE
INSULATION
HOT WATER
OUTLET
TEMPERED
WATER TO
FIXTURE
WARNING
Explosion Hazard
• If the temperature and pressure relief
valve is dripping or leaking, have a
licensed plumber repair it.
• Do not plug valve.
• Do not remove valve.
• Failure to follow these instructions can
result in death or an explosion.
Figure 12 Typical Temperature & Pressure Relief Valve
Installation
TEMPERATURE
AND PRESSURE
RELIEF VALVE
DISCHARGE LINE 19mm (3/4 in.)
MIN. DO NOT CAP OR PLUG.
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