John Wood Commercial - 300-400K BTU - Manual (Page 62)

62
DISCHARGE PIPE
TEMPERATURE-PRESSURE
RELIEF VALVE
Figure 60
If the Temperature-Pressure relief Valve on the water heater
weeps or discharges periodically, this may be due to thermal
expansion.
note:
Excessive water pressure is the most common cause
of Temperature-Pressure relief Valve leakage. Excessive water
system pressure is most often caused by "thermal expansion" in
a "closed system." See Thermal Expansion and Closed Water
Systems on page 14. The Temperature-Pressure relief Valve
is not intended for the constant relief of thermal expansion.
Temperature-Pressure relief Valve leakage due to pressure build
up in a closed system that does not have a thermal expansion
tank installed is not covered under the limited warranty. Thermal
expansion tanks must be installed on all closed water systems.
do not plug the temperature-pressure relief
ValVe opening. this can cause property damage,
serious injury or death.
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.
Vent system
Examine the vent system once a year. Points of inspection are
as follows:
1. Check for obstructions and/or deterioration of the intake air
and/or vent piping and the intake air and vent terminations.
replace immediately where needed.
2. The debris screens in the intake air and vent terminations
should be should be cleaned of foreign material and soot.
See Figure 22 on page 25.
note:
Do not reach inside the vent hood when the heater
is in operation.
3. Check all vent system connections for leakage and repair or
reseal as necessary.
table 14
un-lime® professional delimer
part number description
9005416105
4 - 1 gallon (case)
9005417105 1 - 5 gallon
powered anode rods
To insure a long, trouble-free operating life, the water heaters
covered in this manual are factory equipped with a powered
anode system. The anode rods (2) are of a permanent design
and do not need replacing unless damaged. Inspection and
cleaning should be performed once a year.
note:
Follow the instructions to drain the water heater storage
tank on page 60 first. remove the powered anodes from the
water heater by loosening the 3/4" NPT bushing that forms the
top of the anodes. Do not disassemble the retaining nut and
wire terminal from the top while installed in the water heater, the
anode's electrode may fall inside the tank. remove the entire
anode rod from the water heater prior to inspection. Clean the
anode rods with a soft cloth and reinstall. Follow the instructions
for filling the water heater on page 49 when finished.
drain ValVe and access panels
The water heaters covered in this manual are equipped with a
drain valve, see Features And Components on page 7 for
location. The water heaters covered in this manual are also
equipped with a cleanout opening for sediment and lime scale
removal. See Figure 59 on page 61.
temperature-pressure relief ValVe test
Burn hazard.
Hot water discharge.
Keep clear of Temperature-
Pressure Relief Valve
discharge outlet.
It is recommended that the Temperature-Pressure relief Valve
should be checked to ensure that it is in operating condition
every 6 months.
When checking the Temperature-Pressure relief Valve operation,
make sure that (1) no one is in front of or around the outlet of the
Temperature-Pressure relief Valve discharge line, and (2) that
the water discharge will not cause any property damage, as the
water may be extremely hot. use care when operating valve as
the valve may be hot.
To check the relief valve, lift the lever at the end of the valve
several times, see Figure 60. The valve should seat properly and
operate freely.
If after manually operating the valve, it fails to completely reset
and continues to release water, immediately close the cold
water inlet to the water heater and drain the water heater, see
Draining And Flushing on page 60. replace the Temperature-
Pressure relief Valve with a properly rated/sized new one, see
Temperature-Pressure relief Valve on page 15 for instructions
on replacement.