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Water Piping
Chapter4.–Installation
This appliance is suitable for combination potable water and heating applications. Do not use this appliance if any part has been underwater.
Immediately call a qualied service technician to inspect the appliance and replace any part of the control system and gas control which
has been under water.
If the Combi Boiler is installed with a return line that includes backow preventer, such as one having a backow preventer in the DHW
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 on the heating pressure relief connection and near DHW outlet that is rated in accordance with
and complying with either the Standard for Relief Valves and Automatic Shutoff Devices for DHW Supply Systems, ANSI Z21.22, or 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 199,000 Btu/h. Multiple valves may be used. The pressure relief capacity in DHW pipe must not exceed
150 psig. (The pressure relief capacity on the heating pressure relief valve connection must not exceed 30 psig.) No valve shall be placed
between the relief valve and the Combi Boiler. The relief valve must be installed such that the discharge 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 temperature and pressure relief valve. This valve must also comply with The Standard for Relief Valves
and Automatic Gas Shutoff Devices for DHW 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 ow of water. This may cause unwarranted discharge of the valve.
DHW piping and components connected to the Combi Boiler shall be suitable for use with potable water. Toxic chemicals, such as those
used for Combi Boiler treatment, shall not be introduced into the potable water. A Combi Boiler used to supply potable water may not be
connected to any heating system or components previously 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.
1. 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.
2. Make sure that there are no water leaks from the cold and DHW supply pipes, then insulate the pipes completely.
3. Be sure to also completely insulate the water supply valve and the cold and DHW connections on the Combi Boiler.
4. Do not cover the water drain plug with insulation so that water in the pipe can be drained.
• Use a union coupling or exible 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 the inlet water pressure is too high, insert a pressure regulating 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 in a attic:
About lower-level DHW supply.
If the unit is installed in a attic 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.
4-4. Water Piping
Installation must be performed by a qualied plumber. In the Commonwealth of Massachusetts, this
product must be installed by a licensed plumber or gas tter in accordance with the Massachusetts
Plumbing and Fuel Gas Code 248 CMR Sections 2.00 and 5.00. Observe all applicable codes.
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