Install Instructions

57
Installation & Service Manual
7 Domestic water heaters (continued)
Figure 7-6_Relief Valve - Water heater
Figure 7-7_Water Flow Switch, Water heater
Relief Valve
RELIEF
VALVE
FLOW
SWITCH
FLOW
This appliance is supplied with a relief valve sized in accordance
with ASME Boiler and Pressure Ves sel Code, Section IV
(“Heating Boilers”). The re lief valve is mounted directly into
the heat ex chang er inside the header (see FIG.’s 7-6 and 7-7).
To pre vent water damage, the dis charge from the relief valve
shall be piped to a suit able floor drain for disposal when relief
occurs. No reducing couplings or other restrictions shall be
installed in the discharge line. The discharge line shall allow
complete drainage of the valve and line. Relief valves should
be manually operated at least once a year.
⚠ CAUTION
Avoid contact with hot discharge water.
A water flow switch is available as a factory sup plied option
on all water heaters. The flow switch should be wired
between terminals X and B. Remove the jumper between
the X and B terminals on the terminal strip. This wiring
connection installs the flow switch in the 24 VAC safety
cir cuit to prove water flow before main burner ig ni tion. A
flow switch installed with the fac to ry sup plied minimum
adjustment setting requires a spe cif ic minimum flow to
make the switch and start burner operation. The flow rate
required is a function of the diameter of pipe and tee used for
installation. Ensure that the pump installed water heater will
supply adequate flow to make the flow switch con tacts and
operate the water heater.
Pressure Only Relief Valve
This water heater/hot water supply boiler is nor mal ly supplied
with a temperature and pressure re lief valve sized in accordance
with applicable codes. Units may be supplied with an optional
pres sure only relief valve. When a water heater/hot water
supply boil er equipped with this optional re lief valve is piped to
a separate storage vessel, the storage vessel must have a properly
installed tem per a ture and pressure relief valve which complies
with local codes.
Thermal Expansion
A relief valve which discharges periodically may be due to
thermal expansion in a closed system. A hot water supply
boiler installed in a closed sys tem, such as one with a backflow
preventer or check valve in stalled in the cold water supply,
shall be provided with means to control expansion. Con tact the
water sup pli er or local plumbing inspector on how to correct
this situation. Do not plug or cap the relief valve discharge!
Cathodic Protection
Hydrogen gas can be produced in a hot water sys tem that has
not been used for a long period of time (gen er al ly two weeks
or more). Hydrogen gas is ex treme ly flammable. To prevent
the pos si bil i ty of injury under these conditions, we rec om mend
the hot water faucet be open for several minutes at the kitch en
sink before you use any electrical ap pli ance which is connected
to the hot water sys tem. If hydrogen is present, there will be
an un usu al sound such as air escaping through the pipe as the
hot water begins to flow. There should be no smoking or open
flames near the faucet at the time it is open.
Water Flow Switch (if equipped)