Rinnai Demand Duo R-Series Installation And Operation Manual page 47

This water heater is designed to display diagnostic codes. If there is a potential operation concern, refer
to the code and remedy in this section.
To Display Diagnostic Information
1. Turn off the water heater by pressing the "On/Off" button.
2. Press and hold the "On/Off" for 2 seconds and then the 
(Up) button simultaneously.
3. The last nine maintenance codes display and flash one after
the other.
4. To exit diagnostic codes and return the water heater to
normal operation, press and hold the "On/Off" button for 2
seconds and then the (Up) button simultaneously.
5. Turn on the water heater by pressing the "On/Off" button.
WARNING
Air Supply or Exhaust Blockage
1 0
• Confirm exhaust vent / flue is not
blocked.
• Confirm Intake Filter Exhaust Connector
(IFEC) is not blocked or dirty.
• Check all vent components for proper
connections.
• Ensure approved venting materials are
being used.
• Check fan for blockage.
• Verify High Altitude setting is set
properly.
No Ignition (Heater Not Turning On)
1 1
• Check that the gas is turned on at the
water heater, meter, or cylinder.
• If the system is propane, make sure that
gas is in the tank.
• Ensure appliance is properly grounded.
• Ensure gas type and pressure are
correct.
• Ensure gas line, meter, and/or regulator
is sized properly.
• Bleed all air from gas lines.
• Verify dip switches are set properly.
• Ensure igniter is operational.
• Check igniter wiring harness for damage.
• Check gas solenoid valves for open or
short circuits.
• Remove burner cover and ensure all
burners are properly seated.
• Remove burner plate and inspect burner
surface for condensation or debris.
• Check the ground wire for the PC board.
Demand Duo™ R-Series (REC) Installation and Operation Manual
Some of the checks below should be performed by a licensed professional.
Owners should never attempt any action that they are not qualified to perform.
Figure 44
❷
No Flame
1 2
• 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.
❶
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