Rinnai Demand Duo R-Series Installation And Operation Manual page 48

Thermal Fuse
1 4
• Check for restrictions in air flow around
unit and vent terminal.
• Check gas type of unit and ensure it
matches gas type being used.
• Check for low water flow in a circulating
system causing short-cycling.
• Check for foreign materials in
combustion chamber and/or exhaust
piping.
• Check heat exchanger for cracks and/or
separations.
• Check heat exchanger surface for hot
spots which indicate blockage due to
scale build-up. Refer to instructions in
manual for flushing heat exchanger.
• Hard water must be treated to prevent
scale build up or damage to the heat
exchanger.
• Measure resistance of safety circuit.
• Ensure high fire and low fire manifold
pressure is correct.
• Check for improper conversion of
product.
Over Temperature Warning
1 6
(Safety shutdown because unit is too
hot)
• Check for restrictions in air flow around
unit and vent terminal.
• Check for low water flow in a circulating
system causing short-cycling.
• Check for foreign materials in
combustion chamber and/or exhaust
piping.
• Check for blockage in the heat
exchanger.
Electrical Grounding
1 9
• Check all components for electrical
short.
Outgoing Water Temperature Sensor
3 2
• Check sensor wiring for damage.
• Measure the resistance of the sensor.
(See Electrical Diagnostics)
• Clean sensor of scale build-up.
• Replace sensor if necessary.
Heat Exchanger Outgoing Temperature
3 3
Sensor
• Check sensor wiring for damage.
• Measure resistance of sensor.
• Replace sensor.
48
Combustion Air Temperature Sensor
3 4
• Check for restrictions in air flow around
• Check sensor wiring for damage.
• Measure resistance of sensor.
• Clean sensor of scale build-up.
• Ensure fan blade is tight on motor shaft
• Replace sensor.
Upper Tank Temperature Sensor
3 5
• Check sensor wiring for damage.
• Measure resistance of sensor. (See
• Replace sensor if necessary.
Lower Tank Temperature Sensor
3 6
• Check sensor wiring for damage.
• Measure resistance of sensor. (See
• Replace sensor if necessary.
Inlet water temperature thermistor
5 1
• Check sensor wiring for damage.
• Measure resistance of sensor.
• Clean sensor of scale build-up.
• Replace sensor.
Modulating Solenoid Valve Signal
5 2
• Check modulating gas solenoid valve
• Measure resistance of valve coil.
Combustion Fan
6 1
• Ensure fan will turn freely.
• Check wiring harness to motor for
• Measure resistance of motor winding.
Demand Duo™ R-Series (REC) Installation and Operation Manual
unit and vent terminal.
and is in good condition.
Electrical Diagnostics)
Electrical Diagnostics)
wiring harness for loose or damaged
terminals.
damaged and/or loose connections.