1 flash
Easy Fix
Rheem · HVAC Systems & Water Heaters
Low Heat Call Active
Quick Answer
Error code 1 flash on your Rheem HVAC Systems & Water Heaters means: Low Heat Call Active. This is usually fixable — see the step-by-step guide below.
Likely Causes
How to Fix It
1
Verify the thermostat is calling for first-stage heat as expected
2
Confirm supply air temperature is rising appropriately for low-stage operation
3
No action required if system is operating normally in low heat
Pro Tip
This is a common issue that most users can resolve without specialized tools. Try the first step before moving on to more complex solutions.
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