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.
The Temperature And Pressure Relief Valve:
•
Must be connected to an adequate discharge line.
•
Must not be rated higher than the working pressure
shown on the data plate of the water heater.
The Discharge Line:
•
Must not be smaller than the pipe size of the relief valve
or have any reducing coupling installed in the discharge
line.
•
Must not be capped, blocked, plugged or contain any
valve between the relief valve and the end of the dis-
charge line.
•
Must terminate a maximum of 300mm (12 in.) max
(Canada) or 150mm (6 in.) max (U.S.A.) above a floor
drain or external to the building.
•
Must be capable of withstanding 121°C (250°F) without
distortion.
•
Must be installed to allow complete drainage of both the
valve and discharge line.
•
Must not discharge so as to come in contact with any
electrical part or wiring.
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.
– 12 –
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.
