17
9.
Water Piping
This appliance is suitable for potable water and space heating applications. Do not use this appliance if any part
has been underwater. Immediately call a qualified service technician to inspect the appliance and replace any part
of the control system and gas control which has been under water.
If the water heater is installed in a closed water supply system, such as one having a backflow preventer in the
cold water supply line, means shall be provided to control thermal expansion. Contact the water supplier or a local
plumbing inspector on how to control this situation.
A pressure relief valve must be installed near the hot water outlet that is rated in accordance with and complying with
either The Standard for Relief Valves and Automatic Shutoff Devices for Hot Water Supply Systems, ANSI Z21.22, or
The ANSI/ASME Boiler and Pressure Vessel Code, Section IV ( Heating Boilers ). This pressure relief valve must be
capable of an hourly Btu rated temperature steam discharge of 180,000 Btuh (140,000 Btuh for NR66 series, 120,000
Btuh for NR50 series.) Multiple valves may be used. The pressure relief capacity must not exceed 150 psi. No valve
shall be placed between the relief valve and the water heater. The relief valve must be installed such that the dis-
charge will be conducted to a suitable place for disposal when relief occurs. No reducing coupling or other restriction
may be installed in the discharge line. The discharge line must be installed to allow complete drainage of both the
valve and the line. If this unit is installed with a separate storage vessel, the separate vessel must have its own tem-
perature and pressure relief valve. This valve must also comply with The Standard for Relief Valves and Automatic
Gas Shutoff Devices for Hot Water Supply Systems, ANSI Z21.22. (in the U.S. only). A temperature relief valve is not
required, but if one is used, do not install the valve with the probe directly in the flow of water. This may cause unwar
-
ranted discharge of the valve.
Piping and components connected to the water heater shall be suitable for use with potable water.
Toxic chemicals, such as those used for boiler treatment, shall not be introduced into the potable water.
A water heater used to supply potable water may not be connected to any heating system or components previ-
ously used with a nonpotable water heating appliance.
When water is required in one part of the system at a higher temperature than in the rest of the system, means
such as a mixing valve shall be installed to temper the water to reduce the scald hazard.
• Flush water through the pipe to clean out metal powder, sand and dirt before connecting it.
• Perform the following insulation measures for prevention of freezing.
• Take appropriate heat insulation measures (e.g., wrapping with heat
insulation materials, using electric heaters) according to the climate
of the region to prevent the pipe from freezing.
• Make sure that there are no water leaks from the cold and hot water
supply pipes, then insulate the pipes completely.
• Be sure to also completely insulate the water supply valve and the
cold and hot water connections on the water heater (refer to the fig
-
ure on the right).
• Do not cover the water drain plug with insulation so that water in the
pipe can be drained. (Refer to the figure in the right.)
•
Use a union coupling or flexible pipe for connecting the pipes to reduce the force applied to the piping.
• Do not use piping with a diameter smaller than the coupling.
• When feed water pressure is too high, insert a depressurizing valve, or take water hammer prevention measure.
• Avoid using joints as much as possible to keep the piping simple.
• Avoid piping in which an air holdup can occur.
• If installing the unit on a roof:
• About lower-level hot water supply
If the unit is installed on a roof to supply water to the levels below, make sure that the water pressure supplied
to the unit does not drop below 29 psi. It may be necessary to install a pump system to ensure that the water
pressure is maintained at this level.
Check the pressure before putting the unit into operation.
Failure to supply the proper pressure to the unit may result in noisy operation, shorter lifetime of the unit, and
may cause the unit to shut down frequently.
Installation and service must be performed by a qualified plumber. In the
Commonwealth of Massachusetts, this product must be installed by a licensed
plumber or gas fitter in accordance with the Massachusetts Plumbing and Fuel
Gas Code 248 CMR Sections 2.00 and 5.00. Observe all applicable codes.
Completely insulate
the water inlet and
outlet fittings.
Insulate the water
supply valve completely.
Do not cover the water
drain plug with insulation
so that water in the pipe
can be drained.
