An error code 12 indicates a flame loss. This means that the unit is detecting a flame, but the flame is being extinguished during operation (weak flame).
Most of the same troubleshooting used in the Error Code 11 article can be applied to the error code 12 such as cleaning the flame rod and making sure the unit has sufficient gas to ignite and stay lit. Additionally improper venting could be a cause especially if the unit is Direct Vented (DV) and the air intake is drawing in the exhaust of the unit or another gas burning appliance.
Cleaning Flame Rod:
One of the easiest and most common causes of an error code 12 is a dirty flame rod that can no longer sense the flame. The flame rod can be cleaned with the same materials mentioned in the Error Code 11 article, such as the rough side of a sponge, a fine grit sandpaper or a dollar bill.
Inlet Gas Pressures:
Inlet gas pressure could be an issue. When testing inlet gas pressures we recommend 3 different tests:
- Static Test. This is the inlet gas pressure at the unit when no gas is being used.
- Dynamic Test. This is the inlet gas pressure at the unit when it’s fired up and heating water.
- Max Dynamic Test. This is the inlet gas pressure at the unit when it’s fired up with a high demand and other gas appliances are used (furnace, oven, etc).
Under all 3 tests the inlet gas pressure to the unit should always be above the minimum required gas pressure as stated below or on the unit.
If the inlet gas pressure drops below the minimum rating of the unit, there is an issue in the gas supply that needs to be addressed for the unit to work properly under all conditions.
For California installations there is likely an earthquake safety shut off on the gas line near the meter that may have been tripped during an earthquake or other bump or vibration. Follow the proper reset procedure based on the shut off you have, it’s usually labelled on the device itself.
Troubleshooting gas issues should be left to a professional as there is some serious risk if you’re unfamiliar with what you’re doing.
Check Venting and Termination Installation:
Venting and terminations need to be installed per the guidelines in the installation manual and unit settings (vent type, length, size, etc) need to be set correctly. If the venting is terminated in such a way the unit can pull in it’s own exhaust or the exhaust of another appliance, the unit is likely to lose flame and give an error code 12.
For further technical assistance call 866-766-7489 or use our Contractor Locator to find a local service representative.