On the covered Rheem PowerVent water heater, display 12 and one flash means low flame signal. Rheem's bulletin says the control continues to operate. First, note that the heater is still operating. Then: Rheem's bulletin lists a low flame signal as a condition in which the control continues to operate. Its control settings list a flame prove level and a flame lost level in microamps for a technician measuring the flame signal.
Differential
Likely causes of “Rheem PowerVent water heater display 12 and one flash”, and how to tell them apart
- 1
The flame signal is low, but the control continues to operate
What separates it The status light flashes once and the heater is still heating
How to confirm Note that the heater is still working before you do anything
- 2
A flame sensor that is dirty or coated
What separates it The burner lights but the signal is weak
How to confirm A technician cleans or replaces the flame rod
- 3
A burner that is dirty or partly blocked
What separates it The flame looks yellow or lazy
How to confirm A technician cleans the burner
- 4
Poor combustion air or a restricted vent
What separates it The heater is in a tight space or the vent is partly blocked
How to confirm Check the vent terminations and the air supply
- 5
Wiring or a ground fault in the flame circuit
What separates it The signal comes and goes
How to confirm A technician tests the flame circuit
Before you touch a setting
Record this first — changing settings destroys the evidence
- That the status light shows one flash and the heater still heats
- Whether the water is hot
- How long the code has been showing
- The model and serial numbers
Try in this order
0 of 8 completedWhat to do first
ReversibleNote that the heater is still operating.
Correct only the documented fault domain
ReversibleRheem's bulletin lists a low flame signal as a condition in which the control continues to operate. Its control settings list a flame prove level and a flame lost level in microamps for a technician measuring the flame signal.
Note that the heater is still operating
ReversibleThe code is a warning, not a shutdown, so the water should still heat. Write down the flash pattern and how the water is behaving.
Check the area around the heater
ReversibleMake sure nothing is stored against the heater, that the room is ventilated and that the vent pipe is intact.
Look at the flame through the window
ReversibleIf you can see the burner, a steady blue flame is good. A weak, yellow or flickering flame is worth telling the technician about.
Do not adjust the gas controls
ReversibleGas settings and the flame prove level are for a technician, who works with a flame signal measured in microamps.
Book a service visit soon
ReversibleA low signal can drift lower until the control locks out, so schedule a visit before you lose hot water.
Keep the heater accessible
ReversibleClear the space around it so that the technician can reach the burner and the flame sensor.
Model-specific
What is true of this model and not of its siblings
- The code on this page
- Code 12, one flash: low flame signal.
- Parts involved
- The flame sensor, the burner, the vent and the flame circuit.
- Rheem's guidance
- The control continues to operate, and the flame prove and flame lost levels are listed in microamps for a technician.
Stop boundary
When this stops being a self-service repair
- !Rheem's bulletin lists a low flame signal as a condition in which the control continues to operate, so book service before it gets worse
- !Flame signal work needs a technician with a microamp meter
- !If you smell gas, leave the house and call the gas company
Evidence ledger
Sources behind this answer
Exact questions
Common questions
What does display 12 and one flash mean on a Rheem PowerVent water heater?+
Low flame signal. Rheem's bulletin says the control continues to operate.
Is it an emergency?+
No, the heater still runs, but have it checked before the signal falls further.
What is the flame prove level?+
The control's threshold, in microamps, that tells it that a flame is present, and a technician measures it.
Can I clean the flame sensor myself?+
Gas appliance work is best left to a technician.
What happens if I ignore it?+
The signal can drop below the lockout level and the heater stops heating.