John Wood Direct Vent Models No Longer in Production - Manual (Page 7)

VI) TEMPERATURE & PRESSURE RELIEF
VALVE
For protection against excessive pressure and/or tem-
peratures, a temperature and pressure relief valve has
been installed in the water heater.
ANY REPLACEMENT VALVE MUST NOT EXCEED
THE TEMPERATURE AND PRESSURE RATING.
FAILURE TO INSTALL AND MAINTAIN A NEW, PROP-
ERLY LISTED TEMPERATURE AND PRESSURE
RELIEF VALVE WILL RELEASE THE MANUFACTUR-
ER FROM ANY CLAIMS WHICH MIGHT RESULT
FROM EXCESSIVE TEMPERATURE OR WATER
PRESSURE.
Pressure rating of the valve must not exceed the working
pressure shown on the rating plate of the water heater.
The discharge capacity must be equal to or greater than
the input to the water heater. Temperature and Pressure
Relief valve piping must terminate 152mm (6 in.), no
more than 305mm (12 in.) (reference the applicable
code) above a floor drain or external to the building. Do
not thread, cap, or plug the end of this discharge line. Be
certain that no contact is made with any live electrical
part. Do not connect discharge line directly to drain (see
Figure 2A). To prevent bodily injury, hazard to life or dam-
age to property, the relief valve must be allowed to dis-
charge water in the event of excessive temperature or
pressure developing in the water heater. The function of
the temperature and pressure relief valve is to discharge
water in quantities should circumstances demand. If the
discharge pipe is not directed to drain as shown in Figure
2A, or other suitable means, the water flow may cause
property damage.
The discharge line:
1. must not be smaller than the outlet pipe size of the
relief valve,
2. must not be plugged or blocked,
3. must be material capable of withstanding 99°C
(210°F) without distortion,
4. must be installed so as to allow complete drainage of
both temperature and pressure relief valve,
5. must terminate at an adequate drain, and
6. must not have any valve between the relief valve and
the water heater.
PRESSURE BUILD-UP IN A WATER SYSTEM
During the heating cycle of the water heater the water
expands, creating a pressure build-up in the water sys-
tem. The water supply meter may contain a check valve
or back flow preventer. This will create a closed water
system. A temperature and pressure relief valve must be
installed on the water heater (1034 kPa (150 psi) maxi-
mum pressure setting. See temperature and pressure
relief valve).
If a water heater is installed in a closed water supply sys-
tem, the relief valve will discharge water as the volume
of water expands with rising water temperatures. This is
normal and indicates normal functioning of the relief
valve. Do not plug the relief valve. Only if the discharge
from the relief valve is continuous or for an extended
period of time would this indicate a malfunction. Have
the operation of the heater checked by a qualified serv-
iceman.
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Do not attempt to operate this water heater
with the cold water inlet valve closed.
Manually operate the Temperature and
Pressure Relief valve at least once a year.
Standing clear of the outlet (discharge water
may be hot), lift and release the lever handle
on the Temperature and Pressure Relief
valve to make the valve operate freely.
NEVER OPERATE THE HEATER IF IT IS
NOT COMPLETELY FILLED WITH WATER.
TO MAKE SURE THE HEATER IS FILLED,
OPEN A HOT WATER TAP UNTIL A FULL
FLOW OF WATER IS VISIBLE WITH NO
AIR ESCAPING.
WARNING
1. Have the vent location limitations and minimum
height for vent termination and maximum vent
length been checked?
2. Are the terminal and vent pipes installed and
sealed properly?
3. Has the gas piping been leak tested?
4. Is there at least a 25mm (1 in.) clearance
between the water heater and combustible
materials, 508mm (20 in.) at the top and 25mm
(1 in.) around the vent pipe?
5. Have you taken steps to prevent water damage
in case of leaks?
6. Is the diptube installed in the cold water inlet
connection?
7. Is the water heater completely filled with water?
8. Does the gas piping conform with the recom-
mendations of your Local Gas Utility Company?
9. Is the vent terminal opening unobstructed?
10.Is a temperature and pressure relief valve
installed?
11. Is the drain pipe from the T&P valve unobstruct-
ed?
12.Has all plastic and cardboard packaging
material been removed from the heater and
venting?
Check Here
IF the answer to all of the above questions is “YES” pro-
ceed with lighting the heater.
INSTALLATION CHECK LIST