PLUMBING
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-180.
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 developing a leak, regardless of
being used in a cold, warm or hot region, the cold water supply piping, hot water supply pip-
ing, drain pipe, check valve, valves, expansion tank, and temperature and pressure relief valve
should be protected with sufficient insulation materials to prevent
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.
COLD AND HOT WATER PLUMBING
1.
A water softener is recommended in regions where hard water may be a concern.
2. Do not apply any heat to the unit fittings.
3. Use standard copper alloy unions and fittings for the connections to the unit.
4. Copper piping is recommended for the hot water supply line.
Note: Refer to local codes when considering piping materials. Steel piping is not recommended as it
may cause rust in the piping. Use NPT (NATION PIPE THREAD) for piping of hot and cold water.
5.
Connecting plumbing to the unit, hold unit fittings securely with a wrench to prevent damage to the unit.
6. Installation of a water strainer and the air release valve is recommended.
7.
The distance between the water heater and places where the hot water is used should be as short and direct
as possible, and a uniform pipe size of sufficient diameter to carry the full capacity of hot water should be
used.
8. Be sure to connect the water inlet and the hot water outlet as shown on the water heater. Reversing the
two connections will damage the unit.
9. When hot water flows through the supply line there is an inevitable heat loss, regardless of type of
water heater. Thus, insulation or protection of hot water piping is encouraged.
10. Flush the piping before connecting to the unit.
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.
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