31
insulation does not interfere with the lever of the T&P valve. Secure
all insulation using tape.
T&P Relief Valve
T&P Relief Valve
Drain Line
Manual Relief Lever
T&P Relief Valve Insulation
(Outlet opening on underside)
Figure 37. Installing Insulation Over T&P Valve
TEMPERATURE-PRESSURE RELIEF VALVE
This water heater is provided with a properly rated/sized and certified
combination Temperature-Pressure Relief Valve (T&P relief valve) by
the manufacturer. The valve is certified 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
, and the code
requirements of ASME. If replaced, the new T&P valve must meet
the requirements of local codes, but not less than a combination
Temperature-Pressure Relief Valve rated/sized and certified as
indicated in the previous paragraph. The new 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 Btu/hr or kW input
rate as shown on the water heater’s model rating plate.
Note:
In addition to the factory installed Temperature-Pressure
Relief Valve on the water heater, each remote storage tank
that may be installed and piped to a water heating appliance
must also have its own properly sized, rated and approved
Temperature-Pressure Relief Valve installed.
Explosion Hazard
Temperature-Pressure Relief Valve
must comply with
ANSI Z21.22-
CSA 4.4
and
ASME
code.
Properly sized temperature-
pressure relief valve must be
installed in opening provided.
Can result in overheating and
excessive tank pressure.
Can cause serious injury or death.
For safe operation of the water heater, the Temperature-Pressure
Relief Valve must not be removed from its designated opening
nor plugged. The Temperature-Pressure Relief Valve must be
installed directly into the fitting of the water heater designed for the
Temperature-Pressure Relief Valve. Install discharge piping so that
any discharge will exit the pipe within 6” above an adequate floor
drain, or external to the building. In cold climates it is recommended
that it be terminated at an adequate drain inside the building. 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’ , 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
Temperature-Pressure Relief Valve and the tank. Do not connect
discharge piping directly to the drain. To prevent bodily injury, hazard
to life, or property damage, the temperature-pressure relief valve
must be allowed to discharge water in adequate quantities should
circumstances demand. If the discharge pipe is not connected to a
drain or other suitable means, the water flow may cause property
damage.
Note:
The purpose of a Temperature-Pressure Relief Valve is to
prevent excessive temperatures and pressures in the storage
tank. The T&P valve is not intended for the constant relief of
thermal expansion. A properly sized thermal expansion tank
must be installed on all closed systems to control thermal
expansion. See
Closed Water Systems
and
Thermal Expansion
(page 30).
T&P VALVE DISCHARGE PIPE
Water Damage Hazard
Temperature-Pressure Relief Valve discharge
pipe must terminate at adequate drain.
•
CAUTION
•
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 not be exposed to freezing temperatures.
•
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.
•
Must terminate a maximum of 6” above a floor drain or other safe
place. In cold climates, it is recommended that the discharge
pipe be terminated at an adequate drain inside the building.
•
Shall not have any valve or other obstruction between the
Temperature-Pressure Relief Valve and the drain
DANGER
•
Burn hazard.
•
Hot water discharge.
•
Keep clear of Temperature-
Pressure Relief Valve
discharge outlet.
STORAGE TANK INSTALLATION
Note:
If tank temperature is set above 49°C (120°F) and water is
supplied for domestic use (hand washing, showering, etc.)
install Thermostatic Mixing Valve at each point-of-use to limit
the risk of scald injury. Installation must conform to local code
requirements. If a check valve is installed in the cold water
supply line, an expansion tank must be installed between
the check valve and the water heater’s cold water inlet. Set
