John Wood 6-120, Instruction Manual

9

TEMPERATURE- PRESSURE RELIEF VALVE

This water heater is provided with a properly certi

fi

 ed combination 

temperature - pressure relief valve by the manufacturer.

The valve is certi

fi

 ed by a nationally recognized testing laboratory 

that maintains periodic inspection of production of listed equipment 
of materials as meeting the requirements for Relief Valves for Hot 
Water Supply Systems, ANSI Z21.22/CSA 4.4-current edition, and 
the code requirements of ASME.

If replaced, the valve must meet the requirements of local codes, but 
not less than a combination temperature and pressure relief valve 
certi

fi

 ed as indicated in the above paragraph.

The valve must be marked with a maximum set pressure not to 
exceed the marked hydrostatic working pressure of the water 
heater (150 psi = 1,035 kPa) and a discharge capacity not less 
than the water heater input rate as shown on the model rating plate 
(Electric heaters - watts x 3.412 equal BTU/hr rate).

For safe operation of the water heater, the relief valve must not 
be removed from its designated opening nor plugged.

The temperature-pressure relief valve must be installed directly into 
the 

fi

 tting of the water heater designed for the relief valve.  Position 

the valve downward and provide tubing so that any discharge will 
exit only within 12 inches (300 mm) above an adequate drain,  or 
external to the building or structure.  Be certain that no contact is 
made with any live electrical part.  The discharge opening must not 
be blocked or reduced in size under any circumstances.  Excessive 
length, over 30 feet (9.14 m), or use of more than four elbows can 
cause restriction and reduce the discharge capacity of the valve.

No valve or other obstruction is to be placed between the relief valve 
and the tank.  Do not connect tubing directly to discharge drain 
unless a 12 inch air gap is provided.  The relief valve must be allowed 
to discharge water in suf

fi

 cient quantities, should circumstances 

demand, to prevent bodily injury, hazard to life, or property damage.  
If the discharge pipe is not connected to a drain or other suitable 
means, the water 

fl

 ow may cause property damage.

The Discharge Pipe:

•  Shall not be smaller in size than the outlet pipe size of the valve,
  or have any reducing couplings or other restrictions.

•  Shall not be plugged or blocked.

•  Shall be of material listed for hot water distribution.

•  Shall be installed so as to allow complete drainage of both the 
  temperature-pressure relief valve, and the discharge pipe.

•  Shall terminate a maximum of 12 inches (300 mm) above a 

fl

 oor drain or external to the building.  In cold climates, it is 

recommended that the discharge pipe be terminated at an 
adequate drain inside the building. 

•  Shall not have any shut-off valve between the relief valve and
  tank nor in the discharge pipe.

The temperature-pressure relief valve must be manually operated 
at least once a year.  Caution should be taken to ensure that (1) no 
one is in front of or around the outlet of the temperature-pressure 
relief valve discharge line, and (2) the water manually discharged 
will not cause any bodily injury or property damage because the 
water may be extremely hot.

FIGURE  4.