John Wood Power Direct Vent (ENERGY STAR) - Manual (Page 13)

Water Supply
Piping Installation
Piping, fittings, and valves should be installed according to
the installation drawing (Figure 12). A pressure-reducing
valve and/or an expansion tank may be required for installa-
tions where the water pressure is high. The pressure-reduc-
ing valve should be located on the supply to the entire house
in order to maintain equal hot and cold water pressure.
Important: Heat cannot be applied to the water fittings on
the heater as they may contain nonmetallic parts. If solder
connections are used, solder the pipe to the adapter before
attaching the adapter to the hot and cold water fittings.
Important: Always use a proper grade of joint compound
and be certain that all fittings are drawn up tight.
1. Install the water piping and fi ttings as shown in Figure 12.
Connect the cold water supply to the fi tting (3/4” NPT)
marked “COLD” (or “C”). Connect the hot water supply
to the fi tting (3/4” NPT) marked “HOT” (or “H”).
Important: Some models may contain energy saving heat
traps to prevent the circulation of hot water within the pipes.
Do not remove the inserts within the heat traps.
2. The installation of unions in both the hot and cold water
supply lines is recommended.
3. The manufacturer of this water heater recommends
installing a tempering valve in the domestic hot water line
as shown in Figure 13. These valves reduce the point-
of-use water temperature by mixing cold and hot water.
Contact a licensed plumber or the local plumbing authority.
4. If installing the water heater in a closed water system,
install an expansion tank in the cold water line as specifi ed
under “Closed System/Thermal Expansion”.
5. Install a shut-off valve in the cold water inlet line. It
should be located close to the water heater and be easily
accessible. The owner/operator must be shown the
location of this valve and be given instructions on how to
use it to shut off the water to the heater.
Please note the following:
DO NOT install this water heater with iron piping. The sys-
tem should be installed only with piping that is suitable for
potable (drinkable) water such as copper, CPVC or polybu-
tylene. DO NOT use PVC water piping.
DO NOT use any pumps, valves, or fittings that are not com-
patible with potable water.
DO NOT use valves that may cause excessive restriction to
water flow. Use full flow ball or gate valves only.
DO NOT use any lead based solder in potable water lines.
Use appropriate tin-antimony or other equivalent material.
DO NOT tamper with the gas control/thermostat, igniter,
thermocouple, or temperature and pressure relief valve.
Tampering voids all warranties. Only qualified service tech-
nicians should service these components.
DO NOT use with piping that has been treated with chro-
mates, boiler seal, or other chemicals.
DO NOT add any chemicals to the system piping which will
contaminate the potable water supply.
Closed System/Thermal Expansion
COLD WATER
INLET
COLD WATER SUPPLY
TO FIXTURE
PRESSURE
REDUCING
VALVE
WITH
BYPASS
TEMPERATURE AND
PRESSURE RELIEF VALVE
HOT WATER
OUTLET
COLD WATER
INLET VALVE
THERMAL
EXPANSION
TANK
UNION
DRAIN PAN CONNECT TO
PROPERLY OPERATING
FLOOR DRAIN.
DISCHARGE LINE 305mm
(12 in.) max (CANADA) OR
150mm (6 in.) max (U.S.)
ABOVE DRAIN
Figure 12. Water Piping Installation
IN SOME JURISDICTIONS:
INSTALL A VACUUM RELIEF
IN COLD WATER LINE.
COLD
WATER
INLET
HOT
WATER
OUTLET
TEMPERING
VALVE (SET
TO 49°C
(120°F))
TEMPERED
WATER TO
FIXTURE
Figure 13. Tempering Valve Installation
FOLLOW THE
TEMPERING VALVE
MANUFACTURER'S
INSTRUCTIONS
T&P VALVE
AND
DISCHARGE
LINE
COLD W
ATER
Periodic discharge of the temperature and pressure relief
valve may be due to thermal expansion in a closed water
supply system. The water utility supply meter may contain a
check valve, backflow preventer or water pressure-reducing
valve. This will create a closed water system. During the
heating cycle of the water heater, the water expands caus-
ing pressure inside the water heater to increase. This may
cause the temperature and pressure relief valve to dis-
charge small quantities of hot water. To prevent this, it is
recommended that a diaphragm-type expansion tank (suit-
able for potable water) be installed on the cold water supply
line. The expansion tank must have a minimum capacity of
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