Find out how to fix Rinnai RH180 water heater by using the error codes. The list of the error codes is listed below with a short description of the problem and solution. I will assume that the water heater was installed properly by the qualified technician, per codes and manufacturer’s instructions.
It will be taken into account that Rinnai RH180 gets enough supply of gas and water, pressure is as required, the unit uses correct gas type and the air has been removed (bleed) from the gas lines. Vent pipe has the right length and diameter and there is enough fresh air supplied.
Rinnai RH180 is equipped with the temperature remote controller, which does not only read the temperature but displays the error codes for easier troubleshooting. Recommendation is to contact the licensed professional for most of the issues (error codes).
05 - Air Filter Error
Clean the air filter from the lint and dust build up as it restricts the air flow to the water heater. You can use water and soap for cleaning.
07 - Flow rate is lower than 2.1 gallons per minute
Clean the water filter to remove the blockage or flush the heat exchanger (sediment build-up), also check the circulation pump and wiring.
10 - Blockage in air supply or exhaust pipe
The vent system must be done per manufacturer’s instructions and codes. No obstructions and damages on the pipes, also the vent size and lengths should be according to the instructions. Check the proper connections.
11 - No ignition
Did you bleed the air from gas lines? Check that the dip switch is set correctly, and the unit is properly grounded. Ensure the gas solenoid vale opens properly and there are no short circuits. Make sure that the burners are seated correctly; burner plates are clean from debris and condensation. Check for any damages on the igniter and ignition wires.
12 - No flame
Check power supply for loose connections, proper voltage or voltage drops. Ensure that there are no obstructions in the flue pipes. Flame rod connection is properly connected and is clean of carbon build-up. See are there any shorts at the components and wire harness to control board is not loose. Also check gas solenoid valve for open or short circuits and there is no condensation or debris on the burner plate.
13 - Combustion error
Check the error codes 05 and 10.
FE Flammable Vapor Detected – ALERT. Contact the qualified technician.
14 - Thermal fuse
Ensure the dip switch is set to proper position; there is no restriction in air flow and transfer of flue gases outside. Make sure the water heater gets enough water flow. There should be no foreign materials in combustion chamber and exhaust. See is the heat exchanger damaged; have cracks or separations, or blockages due to mineral deposits.
16 - Over temperature warning
The temperature is increasing and over the allowed range because of the air flow blockages, clogged heat exchanger, foreign material in combustion chamber and exhaust piping. It is required to clean the obstructions.
30 - FV Sensor Error
Make sure that the sensor wiring is not damaged and the reading on the sensor is correct… replace the faulty element.
31 - Burner Sensor Error
Measure the resistance on the sensor and replace it if broken. Check also wiring for damages.
32 - Faulty outgoing temperature sensor on heat exchanger
First try to clean the sensor from scale build-up or fix the wiring if needed. If this doesn't work, measure the resistance on sensor and replace it if it is faulty.
35 - Faulty tank temperature sensor
The same procedure as for error code 32. Also check the sensor position relative to the tank.
38 - CO or FV sensor error
Check the wiring, measure the resistance on the sensor, replace PCB or sensors.
52 - Signal on the modulating solenoid valve abnormal
Check the wiring and its connections for looseness and damages. Measure the resistance of valve coil.
61 - Combustion fan failure
Check the wiring, measure the resistance of motor winding. Make sure the fan can turn freely.
63 - Water flow rate is low (below 1.2 gpm)
Ensure the water filter is not blocked, check the pump for damages and its wiring, flush the heat exchanger as it might be clogged.
71 - SV0, SV1, SV2 and SV3 solenoid valve circuit problem
Check the wiring and make sure the resistance on the solenoid valve coil is within the required resistance.
72 - Flame rod problem
Make sure the flame rod is in contact with the flame, clean the flame rod from carbon build-up. Check the wiring for damages and gas burner for any foreign materials. Replace the flame rod if needed.
73 - Burner sensor circuit fault
Check the wiring and PCB for damage, replace the sensor if needed.
Pictures - courtesy of Rinnai WH company