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Rinnai gas heater code 12: Flame failure

Gas heater, Australia

The flame went out while the heater was running.

This needs a licensed gasfitter. There are a few safe checks you can do first, marked below. Anything inside the unit is a job for a professional.

This involves the gas supply or burner. Only a licensed technician should open the unit or work on gas parts.

What causes it

  1. The gas supply was turned off or interrupted.

    Check the gas supply is onYou can do this

    1. Check whether your other gas appliances, such as the cooktop, are working.
    2. Check the gas isolation valve to the unit is open. On most quarter-turn valves the handle sits in line with the pipe when open.
    3. On bottled LPG, check the cylinder is not empty and the cylinder valve is open.
      If you smell gas, do not use switches or flames. Leave the area and call your gas emergency line.

    Turn the Energysaver heater off and on againYou can do this

    1. Turn the heater OFF using its On/Off button, then turn it ON again.
    2. If the error returns on the next operation, contact Rinnai or a service dealer for a service call.

  2. If it keeps happening with the gas on, the heater needs a service call.

    Book a licensed gasfitter

How to read this code on your unit

Booking a licensed gasfitter

Book a licensed gasfitterlicensed gasfitter

  1. Turn the unit off and leave the covers on. Gas components must only be serviced by a licensed technician.
  2. Note the code, how often it appears, and the model and serial numbers from the rating label.
  3. Book a licensed gasfitter and give them those details.

Models that show this code

6 models in 2 ranges
RangeModels
Energysaver FDT commercial flued gas heaterRHFE-559FTSN (Energysaver 559FDT), RHFE-1005FTSN (Energysaver 1005FDT)
Energysaver FT flued gas heaterRHFE-309FT3 (Energysaver 309FT), RHFE-559FT3 (Energysaver 559FT), RHFE-561FT3 (Energysaver 561FT), RHFE-1005FT3 (Energysaver 1005FT)

Where this comes from

Checked against the manufacturer's manual on 9 October 2026.

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Other Rinnai gas heater codes

Code Meaning What you can do
11 Ignition failure Safe checks first, then a pro
14 Filter blocked or overheat You can often fix it
16 Room overheat You can often fix it
30 Overheat temperature sensor fault Safe checks first, then a pro
31 Room temperature sensor fault Safe checks first, then a pro
32 Room temperature sensor fault Safe checks first, then a pro
33 Overheat temperature sensor fault Safe checks first, then a pro
34 Overheat temperature sensor fault Safe checks first, then a pro
35 Overheat temperature sensor fault Safe checks first, then a pro
40 Sensor tube failure Call a pro
49 Sensor breakdown Safe checks first, then a pro
53 Spark sensor fault Call a pro