BoilerTroubleshooting2026-02-26
Boiler Firing Up Randomly
Random firing can be normal frost protection or a thermostat/control fault.
A boiler that fires when you didn't ask it to may be running a protective function — or have a fault.
Common causes
Frost protection and anti-cycling routines fire the boiler periodically; a faulty thermostat or PCB can also cause random firing.
What to do
If it's cold, brief firing is likely frost protection; frequent random firing warrants a thermostat and control check.
Key takeaways
- Frost protection is normal in cold
- Anti-cycling routines exist
- Frequent random firing = check controls
- Note the pattern for the technician
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