Rinnai tankless water heater error codes

Rinnai tankless water heater code 03

Power was interrupted during a bath fill, so water will not flow when power returns.

Turn off all hot water taps.

Rinnai's tech sheet gives one action for this code: with all hot water taps off, press ON/OFF twice.

Rinnai tankless water heater code 10

Air supply or exhaust blockage, or the condensate trap is full. Rinnai's sheet lists the condensate line, the internal air filter (indoor units), the high-altitude setting, blocked or unapproved venting, vent length, debris in the fan and a stuck check valve between the fan casing and burner body.

Clean a visibly blocked intake screen or air filter and check that the condensate line is draining and not frozen.

Rinnai's checks, in order: the condensate line is not blocked, the internal air filter is clean (indoor units), the high-altitude setting is correct, the combustion air and exhaust vents are not blocked and only approved venting is used, vent length is within limits, the fan is free of debris and turns freely, and the check valve is not stuck. Venting and fan work is professional work.

Rinnai tankless water heater code 11

No ignition: the heater is not turning on. Rinnai's checklist covers the gas supply, the gas type and pressure, air in the gas lines, the ground wire, the flame rod wire, the igniter, the gas solenoid valves and the orifice.

Confirm the gas is turned on at the water heater and meter, or that there is gas in the propane tank.

Rinnai directs, in order: gas on at the water heater, meter or cylinder; propane tank not empty; correct gas type and inlet pressure; air bled from the gas lines; the ground wire on the PC board; the flame rod wire connected; the igniter operating; the gas solenoid valves free of open or short circuits; the gas orifice correct; and the condensate line not blocked. Anything past the shut-off valve and the tank is for a licensed technician.

Rinnai tankless water heater code 12

No flame: the burner lit, or tried to, and the heater did not sense flame.

Confirm the gas is turned on and, on propane, that the tank is not empty.

Rinnai's checks: gas on at the water heater, meter or cylinder; gas in the propane tank; the flame rod wire connected; correct gas type and inlet gas pressure; and air bled from the gas lines. A flame rod that is dirty or a weak gas supply is the usual finding, both technician work.

Rinnai tankless water heater code 16

High outgoing temperature: a safety shutdown because the water heater is too hot.

Turn off the water heater's power and let it cool.

Rinnai directs confirming the fan motor is functioning correctly and replacing the gas valve assembly. Repeated shutdowns are a reason to have the heater serviced.

Rinnai tankless water heater code 19

An electrical grounding fault.

Check that nothing is touching the water heater's wiring and that water has not reached the unit.

Rinnai's only action is to check all components for an electrical short, which is technician work.

Rinnai tankless water heater code 21

Data transfer error.

Note whether the control board was recently replaced.

Rinnai says that if the PC board has been replaced, make sure the data transfer process has been completed.

Rinnai tankless water heater code 25

A condensate pump (accessory) fault. It applies only where a condensate pump is installed.

Empty the condensate reservoir if it is visibly full.

Rinnai directs confirming the wire connections and harness are good and that the condensate reservoir is empty and the condensate pump is operating.

Rinnai tankless water heater code 32

A fault in the outgoing (hot-water outlet) thermistor.

Rinnai's checks for its thermistor codes: check the sensor wiring for damage, measure the sensor's resistance, clean scale from the sensor and replace it. Rinnai prints one list for the outgoing thermistor and the heat exchanger thermistor.

Rinnai tankless water heater code 33

A fault in the heat exchanger thermistor.

Rinnai's checks: check the sensor wiring for damage, measure the sensor's resistance, clean scale from the sensor and replace it. Scale on a sensor is a sign of hard water that also needs treating.

Rinnai tankless water heater code 38

A fault in the exhaust thermistor.

Rinnai lists this code directly above the freeze-protection thermistor with one shared set of checks: check the sensor wiring for damage, measure the sensor's resistance and replace the sensor.

Rinnai tankless water heater code 41

A fault in the freeze-protection thermistor.

Rinnai's checks: check the sensor wiring for damage, measure the sensor's resistance and replace the sensor.

Rinnai tankless water heater code 52

A fault in the gas valve circuit.

Reset the water heater's power once.

Rinnai's checks: check the flame rod and wire for damage, check the gas solenoid valves for open or short circuits, and replace the gas valve assembly. Rinnai also says to call its technical department. Gas-valve work is licensed work.

Rinnai tankless water heater code 63

Recirculation low flow. It applies to units set up for a recirculation loop.

Check whether a recirculation loop shut-off or valve was recently closed.

Rinnai's checks: the bypass plug is removed and a bypass filter installed (in the mode that uses one), the inlet water filter and bypass filter are clean and free of debris, the parameter settings are correct for recirculation mode, the pump supply voltage is present, and air is removed from the recirculation line.

Rinnai tankless water heater code No code displayed

Nothing happens when water flow is activated, and no code is shown. Rinnai treats this as its own entry.

Open a hot tap fully and check that hot and cold lines are not reversed on a new installation.

Rinnai's checks: at least the minimum flow rate required to fire the unit is present, the resistance of the water flow control sensor, the inlet water supply filter is clean, and on new installations the hot and cold lines are not reversed.

Rinnai tankless water heater code SS, 55

Service soon (flush heat exchanger). It is a time-based service indicator set during installation, not a failure. It indicates that it is time to flush the heat exchanger to prevent damage.

Note when the heater was last descaled and whether the water is hard.

Rinnai says to flush the heat exchanger and that hard water must be treated to prevent scale build-up or damage. To reset the 55 code, press the On/Off button on the temperature controller 5 times in 5 seconds.