John Wood Commercial - AJWS - Manual (Page 12)

Temperature and Pressure Relief Valve
For protection against excessive pressures and tempera-
tures, a temperature and pressure relief valve must be
installed in the opening marked “T & P RELIEF VALVE”
(See Figure 9). This valve must be design certified by a
nationally recognized testing laboratory that maintains peri-
odic inspection of the production of listed equipment or
materials as meeting the requirements for Relief Valves and
Automatic Shut-off Devices for Hot Water Supply Systems,
ANSI Z21.22. (CSA4.4, Temperature, Pressure,
Temperature and Pressure Relief Valves and Vacuum Relief
Valves in Canada). The function of the temperature and
pressure relief valve is to discharge water in large quantities
in the event of excessive temperature or pressure develop-
ing in the water heater. The valve's relief pressure must not
exceed the working pressure of the water heater as stated
on the data plate.
Important: Only a new temperature and pressure relief
valve should be used with this 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 or piping 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.
GAS SUPPLY AND PIPING
Gas Requirements
Read the data plate to be sure the water heater is made for
the type of gas being used. This information will be found on
the data plate located on the front of the water heater. If the
information does not agree with the type of gas available, do
not install or operate the water heater. Call your dealer.
Note: An odourant may be added by the gas supplier to the
gas used by this water heater. This odourant may fade over
an extended period of time. Do not depend upon this
odourant as an indication of leaking gas.
Gas Piping
The gas piping must be installed according to all local and
state codes, or in absence of local and state codes, with the
“National Fuel Gas Code”, ANSI Z223.1 (NFPA 54)-latest
edition. Canadian installations must be performed in accor-
dance with CAN/CSA-B149.1.
Note: If using a flexible gas connector, make sure its rating
tag matches or exceeds the input of the water heater.
Tables 2, 3A, and 3B on page 15 provide a sizing reference
for commonly used gas pipe materials. Consult the
12
Figure 9: T&P Relief Valve
Explosion Hazard
Use a new AGA or CSA approved gas supply line.
Install a shut-off valve.
Do not connect a natural gas water heater to a L.P.
gas supply.
Do not connect a L.P. gas water heater to a natural
gas supply.
Failure to follow these instructions can result in
death, explosion, or carbon monoxide poisoning.
WARNING
Explosion Hazard
If the temperature and pressure relief valve is drip-
ping or leaking, have a qualified service technician
replace it.
Do not plug valve.
Do not remove valve.
Failure to follow these instructions can result in
death, or explosion.
WARNING
Discharge line
152mm (6 in)
above drain.
Drain line 19mm
(3/4 in) min.