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WARNING: Plumbing should conform to proper plumbing methods, and in conformance with local codes
or regulations.
A licensed plumber familiar with local codes and ordinances should install the OM-128HH.
CAUTION:
An ANSI (AMERICAN NATIONAL STANDARD INSTITUTE) listed temperature and pressure
relief valve should be installed at the hot water outlet connection of the heater at the time of
installation. Local codes should govern the installation of the relief devices.
If a check valve or one-way valve is required on the cold water supply line, it is recommended
that an expansion tank (100 psi, 8 gal. Min.) should be installed on the hot water supply line.
When the unit is to be installed as a replacement water heater, it is important to determine
whether a check valve has been installed or not.
Remove the check valve before installation of the unit unless a check valve is required by local code.
In order to prevent the water heater from being damaged or develop-
ing a leak, regardless of being used in a cold, warm or hot region, the
cold water supply piping, hot water supply piping, drain pipe, check
valve, valves, expansion tank, and temperature and pressure relief
valve should be protected with sufficient insulation materials to pre-
vent freezing (by wrapping with heat insulation or by equipping with a
freeze prevention heater).
Do not use a smaller pipe for connection at the hot water outlet. Using
a smaller pipe for connection will cause a greater air layer in the top of
the heat exchanger not allowing water to cover the temperature sensor.
Install a pipe as shown in the diagram when using a smaller pipe.
HEATING SYSTEM PLUMBING
NOTE: Select a place where the heating piping for the water heater and end convector can shortened as
much as possible.
NOTE: Make sure the piping for the convector is laid-out properly, and also check for leakage with a pres-
sure test.
NOTE: Circulation pump capacity should be selected in accordance with the water head loss caused by the
required maximum flow and the longest piping.
1.
Install heat insulation material on the hot water piping to prevent heat loss.
2.
In closed systems we recommend the use of an antifreege solution to prevent freezing and corrosion.
Check with the plumbing installer for the proper mix.
3.
Copper or stainless steel or cross-linked polyethylene pipe should be used for the main and branch pipes.
4.
Be sure to connect a hot water pipe with the Expansion Tank, and install at the inlet side of the
Circulation Pump.
5.
Install an Air Separator and Air Release Valve in the hot water pipe to release air inside of the pipe.
6.
Be sure to install a bypass circuit. (Closing the hot water pipe with a thermal valve or temperature con-
trol valve may cause problems in the Circulation Pump.)
7.
Be sure to install unions in the inlet and outlet sides for easy connections and/or removal.
8.
Be sure to install a pressure relief valve on the intake side of the circulation pump used for the heating
piping. Set the pressure relief valve pressure to correspond to the capacity of the expansion tank. See
the items related to setting the pressure relief valve pressure and selection of the expansion tank con-
cerning the capacity of the closed expansion tank.
9.
Use the following water quality when filling the system.
Description
Maximum Levels
7
PLUMBING
pH
Chloride
0.0067 Oz/gal.
6.5 to 8.5
(50 mg/L)
Hot water
outlet
Change to a
smaller pipe here
Hardness
Residual Chlorine
0.0208 Oz/gal.
0.00027 Oz/gal.
(150 mg/L)
(2 mg/L)
Air release
valve
Tee
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