Rheem Error F018: Flue/Combustion Air blockage
The control detected a blockage in the exhaust or intake piping (or a fan backflow flapper not working), preventing safe combustion and shutting the boiler down. We diagnose and repair it across Greater Vancouver — same-day and after-hours.
The control detected a blockage in the exhaust or intake piping (or a fan backflow flapper not working), preventing safe combustion and shutting the boiler down.
Rheem fault codes can vary by model and series. Use this as a guide — the same code can have more than one cause. Our Technical Safety BC–licensed technicians read the code, confirm it against your unit's manual, and diagnose the true cause before any repair.
Likely causes of Rheem error F018
- Obstructed intake or exhaust vent terminal (debris, ice, nests)
- Disconnected, sagging or restricted vent pipe
- Fan backflow flapper stuck or failed
- Excessive vent length / improper installation
What you can safely check
- Inspect and clear the outdoor vent/intake terminals
- Make sure nothing has been placed against the exterior vent pipes
Beyond these checks, do not open the unit or touch gas/electrical parts — BC law requires a licensed gas fitter. Call us for a proper diagnosis.
Error F018 usually leaves you without heat or hot water and can indicate a safety-related fault. Don't keep resetting it — call for priority after-hours Rheem repair.
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Parts often behind Rheem error F018
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Rheem Error F018 Repair Across Metro Vancouver
Frequently Asked Questions
Fix Rheem Error F018 Today
Licensed Rheem diagnosis and repair with genuine parts — same-day and after-hours across Greater Vancouver.
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