Relief Valve; Water Flow Switch - Primera 400B Installation & Maintenance Manual

Cathodic Protection
In hot water systems utilizing cathodic protection, Hydrogen gas can be produced when the hot water system has not
been used for a long period of time (generally two weeks or more). Hydrogen gas is extremely flammable. To pre-
vent the possibility of injury under these conditions, one of the hot water system faucets should be opened for several
minutes before using any electrical device connected to the hot water system. If hydrogen is present, there will be an
unusual sound such as air escaping through the pipe as the hot water begins to flow. Do not smoke, have open flames
or turn electrical switches on or off near the faucet at the time it is open.

Relief Valve

®
PRIMERA heating boilers are normally supplied with a pressure only relief valve(s) sized in accordance with the
ASME Boiler and Pressure Vessel Code, Section IV.
®
PRIMERA water heaters and hot water supply boilers are normally supplied with a temperature and pressure relief
valve(s) sized in accordance with ASME Boiler and Pressure Vessel Code, Section IV.
The relief valve(s) is installed in the hot water outlet. No valve or obstruction is to be placed between the relief valve,
and the hot water outlet of the unit.
Caution: Do not install a reducing coupling, valve or other restriction in the relief valve(s) discharge line. The discharge
line shall allow complete drainage of the valve and line. Relief valves should be manually operated at least once a
year.
Warning: To prevent burns caused by hot water discharge and water damage, pipe the discharge from the
relief valve to a suitable floor drain for disposal when relief occurs. Avoid contact with hot discharge water.
Optional Relief Valve
®
PRIMERA water heaters certified to ANSI Z21.13 (for hot water supply boilers) may be supplied with an optional
pressure only relief valve(s). When a heater equipped with this optional pressure only relief valve is piped to a
separate storage vessel, the storage vessel must have a properly installed temperature and pressure relief valve which
complies with the Standard for Relief Valves and Automatic Gas Shutoff Devices for Hot Water Supply Systems, ANSI
Z21.22.
Thermal Expansion
A relief valve that discharges periodically may be due to thermal expansion in a closed system, such as water heaters
or hot water supply boilers installed in a system closed by components, such as a backflow preventer or check valve in
the cold water supply or a closed boiler heating loop. These systems must be provided with means to control
expansion. Contact a boiler or plumbing professional to resolve this situation. Do not plug the relief valve.

Water Flow Switch

Units are equipped with a factory installed water flow switch in the discharge piping. A minimum of 30 GPM (20 GPM
for model 400 and 540) is required to "turn on" (make) the flow switch and start burner operation. The water flow switch
meets code requirements for a low-water cut off device on boilers requiring forced circulation for operation. Low water
cutoffs are designed for use on tank type equipment with defined water levels and are not appropriate for use on
equipment, such as the PRIMERA
®
., that require forced circulation to operate.
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