On the covered Rheem PowerVent water heater, display 31 and four flashes means thermal cut-off limit lockout. Rheem's bulletin lists the ECO limit as 199°F (93°C) and says an ECO limit lockout is indefinite. First, turn the water heater's gas control to off and let the tank cool.
Differential
Likely causes of “Rheem PowerVent water heater display 31 and four flashes”, and how to tell them apart
- 1
The water temperature reached the thermal cut-off limit, and the control has locked out
What separates it The status light flashes four times and there is no hot water
How to confirm Turn the water heater's gas control to off and let the tank cool
- 2
A thermostat or temperature sensor that has failed
What separates it The water was far hotter than the setting
How to confirm A technician tests the sensor and the control
- 3
A gas valve that stays open
What separates it The burner kept firing after the set point
How to confirm A technician checks the valve
- 4
Scale or sediment that makes the tank overheat locally
What separates it The tank has not been flushed for years
How to confirm A technician flushes the tank
- 5
A control board fault
What separates it Everything else tests well
How to confirm A technician replaces the control
Before you touch a setting
Record this first — changing settings destroys the evidence
- That the light flashes four times
- Whether the water was very hot before the lockout
- How old the heater is and when it was last flushed
- The model and serial numbers
Try in this order
0 of 8 completedWhat to do first
ReversibleTurn the water heater's gas control to off and let the tank cool.
Correct only the documented fault domain
ReversibleRheem's timing table says an ECO limit lockout lasts indefinitely, so it does not clear itself. A water heater that reached its energy cut-off limit needs a technician to find why.
Turn the gas control to off
ReversibleSet the gas control to OFF so that the burner cannot fire while the tank is hot.
Let the tank cool
ReversibleWait for the water to cool fully before anyone touches the tank, since the water may be near 199 degrees Fahrenheit.
Do not reset repeatedly
ReversibleThe lockout is indefinite and does not clear itself, so resetting over and over without finding the cause is unsafe.
Use hot water with care
ReversibleIf any hot water is drawn, mix it with cold, because the tank may still be very hot.
Call a technician
ReversibleA water heater that reached its energy cut-off limit needs a technician to find out why, as Rheem's bulletin states.
Ask about flushing and the thermostat
ReversibleThe technician will check the sensor, the valve and the sediment in the tank.
Model-specific
What is true of this model and not of its siblings
- The code on this page
- Code 31, four flashes: thermal cut-off limit lockout.
- Parts involved
- The ECO limit, the temperature sensor, the gas valve and the control.
- Rheem's guidance
- The lockout is indefinite, so a technician must find the cause.
Stop boundary
When this stops being a self-service repair
- !Rheem's timing table says an ECO limit lockout lasts indefinitely, so it does not clear itself and needs a technician to find why
- !Do not keep resetting the heater
- !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 31 and four flashes mean on a Rheem PowerVent water heater?+
Thermal cut-off limit lockout. Rheem's bulletin lists the ECO limit as 199°F (93°C) and says an ECO limit lockout is indefinite.
What is the ECO limit?+
Rheem's bulletin lists it as 199 degrees Fahrenheit (93 degrees Celsius).
Will it clear itself?+
No, Rheem's timing table says an ECO limit lockout lasts indefinitely.