John Wood Commercial - AJWSC - Manual (Page 14)

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 & Pressure Relief Valve:
• Must not be in contact with any electrical part.
• 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 BTUH rating of the T&P valve must be greater than,
or equal to, the input rating 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 152mm (6 in.) 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.
– 14 –
Figure 10 Commercial Unit with Auxiliary Storage Heater - Forced Circulation With or Without Building Recirculation -
Front Inlet/Outlet Connections
Note: Install a vacuum
relief valve if required
by local codes.
45mm (1 1/2 in.)
Cold water supply
Shut-off Valve Shut-off Valve
Shut-off Valve
Heater
Thermometer
Temperature and
Pressure Relief Valve
Temperature
and Pressure
Relief Valve
Thermal
Expansion
Tank
Pressure
Reducing
Valve
Hot Water
Outlet
Storage Tank
Plug
Cock
Circulating
Pump
Check
Valve
Figure 9 T&P Relief Valve
Temperature
and Pressure
Relief Valve
Discharge line
152mm (6 in.)
above drain.
Drain
Drain line 19mm
(3/4 in.) min.