Expansion Tank On The Cold Water Supply Line; Domestic Hot Water Pressure Relief Valve; Thermostatically Controlled Mixing Valve (Included) - COMBOMAX ULTRA Installation Use And Care Manual

3.8.2 Expansion tank on the cold water
supply line
Check if there is a device with a backflow
preventer on the cold water supply line before
the tank.
Such items may create a closed system and
prevents the water as it is being heated from
expanding back into the cold water supply line.
Unless there is a device to absorb this volume
increase, the resulting pressure increase could
cause the relief valve operate during a heating
cycle. In the long run, this operation could cause
premature failure of the relief valve and possibly
of the water heater itself.
If plumbing devices on which the Combomax
Ultra is installed don't prevent water hammer on
the network, it could cause the relief valve to
open on the domestic hot water side.
Replacing the relief valve will not correct the
problem. One method of preventing pressure
build-up is to install a domestic water expansion
tank on the cold water supply line before the
Combomax Ultra boiler unit. Contact your
installing contractor, supplier or local plumbing
inspector.
3.8.3 Domestic hot water pressure relief
valve
The COMBOMAX ULTRA boiler is factory
equipped with a pressure relief valve installed on
the domestic hot water outlet. This pressure
relief valve is set at 860 kPa (125 psi). Connect
both the domestic hot water (862 kPa / 125 psi)
and the tank heating system (207 kPa / 30 psi)
pressure relief valves downward toward safe
location.
Relief valve outlet pipe diameter must not be of
smaller diameter than the relief valve outlet. The
oulet pipe end must be visible in order to
observe any relief incident and be protected
from freezing.
3.8.4 Thermostatically controlled mixing
valve (included)
The COMBOMAX ULTRA boiler boiler is factory
equipped with a thermostatically controlled
mixing valve that reduce the risk of scald injury
by lowering the domestic hot water temperature
at the heat exchanger outlet, by mixing cold
fresh water to the hot water coming out of the
heat exchanger.
In order to adjust the mixing valve, hot water
must be consumed. (See section 5.6)
11.
COMBOMAX ULTRA Electric Boiler Installation, Use and Care Manual , Page
(Revision june 2016)