Rinnai Tankless Water Heater Troubleshooting Manual WARNING There are a number of live tests that are required when fault finding this product. Extreme care should be used at all times to avoid contact with energized components inside the furnace. You MUST be a qualified service person before proceeding with these test instructions. Before checking resistance readings, turn off power source to unit and then isolate each item to be checked from the circuit by unplugging it.
Table of Contents Code Numbers Page # 03 ……………………………………………………………………………………………………………………………………………… 4 05 ……………………………………………………………………………………………………………………………………………… 5 10 ……………………………………………………………………………………………………………………………………………… 6 11 ……………………………………………………………………………………………………………………………………………… 8 12 ……………………………………………………………………………………………………………………………………………… 11 14 ……………………………………………………………………………………………………………………………………………… 15 16 ……………………………………………………………………………………………………………………………………………… 17 19 …………………………………………………………………………………………………………………………
No Code ……………………………………………………………………………………………………………………………………. 36 LC, LCO – LC9 .…………………………………………………………………………………………………………………………… 37 FF ………..……………………………………………………………………………………………………………………………………. 38 Cold Water Sandwich caused by Faulty Fixture…….. …………………………………………………………………. 39 Cold Water Sandwich caused by Low Flow .………………………………………………………………………………. 40 How to retrieve flow rate/temperature output with the MC‐91‐1 & MC‐91‐2 Controller….
Code 03 Troubleshooting Procedure Power interruption during bath fill (Water will not flow when power returns) 1. Turn of all hot water fixtures in building. Next press the ON/OFF button on the temperature controller twice.
Code 05 Troubleshooting Procedure Bypass Servo 2. Turn off power supply to unit, reapply power. Fire up unit. If code 05 reappears replace bypass valve.
Code 10 Troubleshooting Procedure Air Supply or Exhaust Blockage Request pictures of the entire vent system inside/outside the home or business. Review pictures looking for clearance issues, improper venting or materials used, etc. File all pictures in Syteline under incident number. 1. Perform this test only if the unit is coding out during your service call. Remove the vent system from the top of the water heater. Fire the product and see if the unit will operate without the vent system connected.
10. Remove burner manifold and inspect for insects or other debris in air channel for restriction. 11. Remove burner and inspect copper fins in heat exchanger for a build up between fins. This will cause air flow restrictions which can lead to code 10's. If build up is present, you will need an air compressor capable of delivering 120 psi of air to blow out the burner and heat exchanger fins. If unable to clean the heat exchanger with compressed air replace the heat exchanger.
Code 11 Troubleshooting Procedure No Ignition Request pictures of the gas piping, meter, regulator, tank and any flex connectors used in the system. In addition; have the installer remove the front cover and forward you pictures of the heat exchanger, fan motor, and the area around the flame rod. Review these pictures looking for improper sized gas lines, regulators, tanks, signs of water leaks or heat damage to components inside the unit’s casing. File all pictures in Syteline under incident number. 1.
10. Look into view window on appliance to see if you ever see a flame in the burner box while the unit is going through the ignition cycle. If you do that indicates an issue in the flame rectification circuit. This could be a buildup of carbon or a white substance on flame rod, bad connection at flame rod, loose or damaged flame rod, bad PC board, gas valve or low inlet gas pressures. Before replacing the PC board or gas valve continue troubleshooting the steps below. 11.
connected please install one per Rinnai venting instructions. If a condensate line is in use, inspect the vent connector on top of water heater to ensure it’s not stopped up. In addition; check the condensate drain trap and line for blockage. If stopped up remove vent pipe from unit and clean out all debris and/or build up from the trap or line. 18. Check to ensure all two stages regulators are installed at least six foot away from appliance.
Code 12 Troubleshooting Procedure Flame Failure Request pictures of the gas piping, meter, regulator, tank and any flex connectors used in the system. In addition; have the installer remove the front cover and forward you pictures of the heat exchanger, fan motor, and the area around the flame rod. Review these pictures looking for improper sized gas lines, regulators, tanks, signs of water leaks or heat damage of components inside the unit’s casing. File all pictures in Syteline under incident number.
ensuring you have at least three gpm's of flow through the water heater. You can use the unit's key pad to check your flow rate to verify three plus gpm's. Then; place the unit into forced low fire and follow the gas pressure setting procedure to adjust the low fire gas pressure. Next place the unit into forced high fire per gas pressure setting procedure. Adjust high fire pressure per instructions. Improper manifold gas pressures can lead to code 12's. 4.
where the condensate is coming from. It could be a venting issue or leak inside the heat exchange combustion box area. 13. Ensure installer used the condensate drain tap as recommended by Rinnai on the vent terminal connection at the top of the water heater, non‐condensing product. If the condensate drain line is not connected please install one per Rinnai venting instructions. If a condensate line is in use, inspect the vent connector on top of water heater to ensure it’s not stopped up.
unit will try to fire three times. That will not occur on the immediate code 12. The fan motor may try to come on but immediately goes into a code. The immediate code 12 or 19 is an indication of a short circuit within the appliance. Could be a short in a wiring harness, water flow control or bypass valve or any other component within the DC circuit. One way to track this down is to unplug one component at a time and try to cycle the unit on.
Code 14 Troubleshooting Procedure Thermal Fuse or Overheat Request pictures of the internal components inside the water heater’s casing especially around the heat exchanger where the copper section meets up with the combustion box. You are looking for discoloration of the heat exchanger surface in that area. File all pictures in Syteline under incident number. Note; Code 14 is an indication of overheating and should be taken seriously.
Increase set point of aqua‐stat by at least twenty degrees lower than the water heater's set point. This will normally stop the unit from short cycling. 9. Inspect burner manifold, burner assembly and heat exchanger copper fins for debris build‐up or blockage. If you find debris build‐up inside the heat exchanger that has led to a code 14, replace the heat exchanger. 10. Inspect the front, sides and back of the heat exchanger surface for cracks, separations, discoloration or damage of any kind.
Code 16 Troubleshooting Procedure Over Temperature Warning (Safety shutdown because unit is too hot) 1. Check for low flow in circulation system causing short cycling. 2. Check for foreign materials in combustion chamber and/or exhaust piping. 3. Check for blockage in the heat exchanger fins. 4. Clean out heat exchanger fins or replace heat exchanger.
Code 19 Troubleshooting Procedure Electrical Grounding 1. Check all components for electrical short.
Code 25 Troubleshooting Procedure Condensate Trap is full 1. Inspect condensate drain line for blockage. 2. Inspect condensate trap and tank inside cabinet for blockage. 3. Ensure condensate line has an air gap between the unit and drain line leaving the water heater. 4. Check sensor wiring harness for loose, broken or damaged connections from sensor back to PC board. 5. If condensate tank is draining and the unit is still throwing a code 25 replace condensate tank with sensor.
Code 31 Troubleshooting Procedure Burner Thermocouple 1. Check low/high fire manifold pressures for proper settings. See gas pressure setting procedure located under the front cover of unit in the technical data sheet. In addition, can be found in the product’s service manual. Set manifold pressures per instructions for your altitude. 2. Verify all dip switches are set to the proper position on the PC board. See technical data sheet for proper settings at your altitude. 3.
Code 32 Troubleshooting Procedure Outgoing Water Temperature Thermistor Fault 1. Check thermistor wiring harness for loose, broken or damaged connections from thermistor back to PC board. 2. Turn off water supply to the water heater and drain system down. With no water left in hot water supply lines remove the thermistor and check for scale build up on thermistor. Clean off any substance found on this component. Proceed to item #3 below. 3.
Code 33 Troubleshooting Procedure Heat exchanger outgoing thermistor 1. Check thermistor wiring harness for loose, broken or damaged connections from thermistor back to PC board. 2. Turn off water supply to the water heater and drain system down. With no water left in hot water supply lines remove the thermistor and check for scale build up on thermistor. Clean off any substance found on this component. Proceed to item #3 below. 3.
Code 34 Troubleshooting Procedure Combustion air temperature thermistor (Internal units ONLY) 1. Check thermistor wiring harness for loose, broken or damaged connections from thermistor back to PC board. 2. Remove thermistor from fan motor housing and check resistance readings of this component using a volt/ohm meter capable of reading 20K ohms. Set meter to proper setting for checking 20K ohms and insert meter leads into each end of the thermistor plug. Then apply heat to the thermistor bulb.
Code 41 Troubleshooting Procedure Freeze Protection Sensor for External Units 1. Check sensor wiring harness for loose, broken or damaged connections from sensor back to PC board. 2. Ensure sensor is open to outside air and not covered with insulation. 3. With water supply still isolated and sensor removed from unit, check the resistance readings of this component using a volt/ohm meter capable of reading 20K ohms.
Code 51 Troubleshooting Procedure Inlet Water Temperature Sensor 1. Check sensor wiring harness for loose, broken or damaged connections from sensor back to PC board. 2. Turn off water supply to water heater and drain system down. With no water left in hot water supply lines remove the sensor and check it for scale build up. Clean off any substance found on this component. Proceed to item #3 below. 3.
Code 52 Troubleshooting Procedure Modulating Solenoid Valve Signal Abnormal (POV) 1. Check wiring harness for loose, broken or damaged connections from POV valve back to PC board. 2. Unplug POV valve using a volt/ohm meter and check resistance readings across the POV coil on the gas valve. The proper resistance reading for this coil can be found in the Tech Data Sheet found on the back side of the unit’s front panel or in the Rinnai Water Heater Service Manual for that model unit.
Code 57 Troubleshooting Procedure Burner Overheat Bi‐metal Switch 1. Check burner overheat bi‐metal switch wiring harness for loose, broken or damaged connections from sensor back to PC board. 2. Verity unit is connected to the proper type gas. Example; if a natural gas unit, should be connected to natural gas. 3. Verify low/high fire manifold pressures are set properly. See gas pressure setting procedures for pressure setting at your elevation. 4. Clean sensor. 5.
Code 58 Troubleshooting Procedure Secondary Heat Exchanger Sensor 1. Check sensor wiring harness for loose, broken or damaged connections from sensor back to PC board. 2. This code indicates a scale build‐up inside the secondary heat exchanger and it needs to be flushed to prevent damage. Refer to flushing instructions in the owner manual. Hard water must be treated to prevent scales build‐up or damage to the heat exchanger will occur.
Code 61 Troubleshooting Procedure Combustion fan Motor NOTE: Before servicing fan motor turn off power supply to the unit. Never attempt to plug up or unplug motor while power is supplied to product. Failure to follow this procedure could lead to damaged components including fan motor. 1. Check wiring harness for loose, broken or damaged connections from fan motor back to PC board. 2. Remove fan motor with power supply to product turned off. Inspect blower wheel to ensure it turns freely. 3.
Code 65 Troubleshooting Procedure Water Flow Servo 1. Check wiring harness to the water flow servo for loose, broken or damaged connections from servo back to PC board. 2. Turn off the power to the water heater and then reapply to see if code resets. 3. The water flow servo valve has failed to close during the bath fill function. Immediately turn off the water flow and discontinue the bath fill function. 4. Replace water flow control servo.
Code 70 Troubleshooting Procedure PC Board Fault 1. Check all wiring harness at the connection to the PC board to ensure they are not loose, broken or damaged. 2. Check all dip switches to ensure they are set to the proper position. 3. Replace PC board.
Code 71 Troubleshooting Procedure SV0, SV1, SV2, SV3 Solenoid Valve Fault NOTE: Before servicing product disconnect power supply to the unit. 1. Check wiring harnesses to SV0, SV1, SV2 and SV3 for loose, broken or damaged connections from gas valve solenoids back to PC board. 2. Check for moisture in plastic tubing on internal units from bottom of combustion box back to gas valve. If moisture is found in this tube replace gas valve.
Code 72 Troubleshooting Procedure Flame Sensing Device Fault NOTE: Before servicing product disconnect power supply to the unit. 1. Check wiring harnesses to flame rods for broken or damaged connections from flame rod back to PC board. 2. Ensure flame rod is touching flame when unit fires. 3. Remove flame rod and check for carbon build‐up. Clean flame rod with dollar bill. 4. Check inside burner for debris build up that may be shorting out flame rod.
Code 73 Troubleshooting Procedure Burner Thermocouple Fault 1. Check wiring harness at burner thermocouple back to PC board for loose, broken or damaged wiring or connections. 2. Verify all dip settings are set to the proper alitiube per the tech sheet found under the front panel of your unit. This information can also be found in the product’s service manual. 3. Confirm low/high fire manifold gas pressures are set to factory specification per alitiube unit is installed at.
Code 79 Troubleshooting Procedure Water Leakage Detected 1. Check wiring harness at leak detector for loose, broken or damaged wiring or connections. 2. Check the heat exchanger and all piping inside the unit for leaks. 3. If no leaks are found inspect inside of cabinet for signs of water pooling on bottom pan of water heater. Wipe or blow out any water found in cabinet. Dry off leak sensor and restart unit. 4. If no water is found in cabinet unplug sensor and fire water heater.
No Code Troubleshooting Procedure Nothing happens when water flow is activated 1. Clean water inlet filter to water heater. 2. On new installations ensure the hot/cold water lines are not reversed. 3. Ensure you have the minimum flow rate required to fire the unit. 4. Ensure water flow control turbine spins freely. 5. Measure the resistance of the water flow control sensor, see technical data sheet behind front cover of unit for proper readings. 6.
Code e LC, LC0 – LC9 Troublesh hooting Procedu ure Scale build‐up in Heat Excchanger p supplyy to the unit. NOTEE: Before servicing productt disconnect power 1. Flush heat exchanger e perr recommend ded flushing pprocedure fou und in unit’s o owner’s manual. 2. NOTE; the LC, LC0 – LC9 codes c are the e only codes tthat will allow w a unit to con ntinue to opeerate. Th he display will alternate be etween the LC codes and tthe temperatture setting. TThe controller will co ontinue to be eep.
Code FF Troubleshooting Procedure Indicates a serviceman has serviced product This code indicates a service provider performed maintenance or repair. The serviceman will enter the following code FF after making repairs to the product. That flags the system indicating all codes after the FF took place after he made his repairs. You can enter the FF code by; pressing the up, down and ON/OFF buttons simultaneously.
Cold Water Sandwich caused by faulty fixture: 1. Have customer explain problem. 2. Turn off hot water ball valve on the Rinnai valve kit at the water heater. This should shut off the water flow to all hot water fixtures at the location. Turn on a hot water fixture to check and see if any water continues to flow at that fixture. After roughly two minutes all residual water in the system should bleed down to no flow at your fixtures.
Cold Water Sandwich caused by Low Flow: 1. Open fixture and record flow rate using the water heater’s temperature control pad. 2. Shut off hot/cold water feed lines to the water heater, remove inlet water filter and check for debris, clean if necessary. Re‐install filter, turn on water supply. Open the same tap again and recheck your flow rate to see if it increased. If flow rate is less than one gpm remove the restrictor and clean the strainer in that fixture.
when the water is turned back on within a few minutes of the demand system cycling, and cold water sandwich is created. j. Loose or bad electrical connection inside the water heater or power supply to product. Power supply could be dropping out momentarily due to a component heating up, loose wiring connections, etc. k. Low flow shower heads especially in area with high ground water temperatures.
How to re etrieve flow w rate/tem mperature output 42