Safety Devices - Rinnai REU-24 W-A Service Manual

Flame Failure
Situated on both sides of the burner, the flame rods monitor normal combustion, preventing any
discharge of gas to the burner if there is no flame and in conjunction with the P.C.B., isolate the gas.
Remaining Flame Safety Device
If the flame remains on the burner after the tap is closed, and the water temperature inside the heat
exchanger reaches 2OO"C, a DC 90 volt bi-metal cut-off switch isolates the gas to the solenoids.
Boiling Protection
The
heat exchanger outlet water temperature thermistor continually monitors the temperature of the
water flowing from the heat exchanger. Should the temperature of the water at this point reach 105°C
then a signal will be sent to the P.C.B. to shut off the solenoids and isolate the gas.
No Water
Should the incoming water flow become restricted or stop, then the water flow sensor will cease to
send a magnetic pulse signal to the P.C.B., in turn isolating the flow of gas to the burner.
F u s i b l e L i n k
Is located on the internal rear of the casing. If the heat exchanger bums out, or the temperature
outside it reaches 152T, this device isolates the gas supply, and shuts down the unit completely.
Pressure Relief Valve
Located on the hot water outlet, this spring and valve seating type valve will, if the pressure inside
the heat exchanger reaches 1400 kPa, release the built up pressure until 1000 kPa is maintained.
Combustion Fan Revolution Check
The
combustion fan rpm are continually monitored by a magnetic pulse counter connected to the
P.C.B. If the fan revolutions deviate from the speed required for complete combustion, a signal is sent
to the P.C.B. and the revolutions adjusted accordingly.
Automatic Frost Protection
When the outdoor temperature drops below 3.5T, the frost sensing device is activated, and the anti-
frost heaters prevent the water in the appliance from freezing. These anti-frost heaters remain ON until
the outdoor temperature rises to 11 .S'C. There are 5 anti-frost heaters located at various points in the
appliance. The anti-frost protection device will prevent freezing down to -20°C in a no wind situation,
and -15°C in a windy situation.
Water Bypass Distributor
Water at 60°C from the heat exchanger is mixed with cold water via the bypass system when
preset temperature selected at the remote controls is less than 60°C.
Thermocouple
A thermocouple situated on the right hand side of the burner continually monitors combustion by
checking the tile temperature. Information is fed back to the P.C.B., which adjusts the air/gas ratio
if necessary.

SAFETY DEVICES

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