Installation Manual

Demand Duo™ R-Series Installation and Operation Manual 45
16
Over Temperature Warning
(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.
19
Electrical Grounding
• Check all components for electrical
short.
32
Outgoing Water Temperature Sensor
33
Heat Exchanger Outgoing Temperature
Sensor
• Check sensor wiring for damage.
• Measure resistance of sensor.
• Clean sensor of scale build-up.
• Replace sensor.
34
Combustion Air Temperature Sensor
• Check for restrictions in air flow around
unit and vent terminal.
• Check sensor wiring for damage.
• Measure resistance of sensor.
• Clean sensor of scale build-up.
• Ensure fan blade is tight on motor shaft
and is in good condition.
• Replace sensor.
51
Inlet water temperature thermistor
• Check sensor wiring for damage.
• Measure resistance of sensor.
• Clean sensor of scale build-up.
• Replace sensor.
52
Modulating Solenoid Valve Signal
• Check modulating gas solenoid valve
wiring harness for loose or damaged
terminals.
• Measure resistance of valve coil.
12
No Flame
• Check that the gas is turned on at the
water heater, gas meter, or cylinder.
• Check for obstructions in the flue outlet.
• If the system is propane, make sure that
gas is in the tank.
• Ensure gas line, meter, and/or regulator
are sized properly.
• Ensure gas type and pressure are
correct.
• Bleed all air from gas lines.
• Ensure proper venting material was
installed.
• Check power supply for loose
connections.
• Check power supply for proper voltage
and voltage drops.
• Ensure flame rod wire is connected.
• Check flame rod for carbon build-up.
• Disconnect and reconnect all wiring
harnesses on unit and PC board.
• Check for DC shorts at components.
• Check gas solenoid valves for open or
short circuits.
• Remove burner plate and inspect burner
surface for condensation or debris.
14
Thermal Fuse has activated
• Check for restrictions in air flow around
unit and vent terminal.
• Ensure dip switches are set to the proper
position.
• Ensure dip switch 5 in the second bank
of dip switches (white) is in the off
position.
• 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.