Poolworld
Short Cycling / Unstable Flame or Safety Interruption
Heater starts then shuts off after a few seconds; may cycle on and off repeatedly without error code
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Weak flame signal, Intermittent pressure switch operation, Loose safety circuit wiring, Unstable gas pressure
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas before inspecting internal components.
- Check water flow: Ensure the pump is running steadily and that the filter is clean. Intermittent flow can cause safety switches to open.
- Inspect flame sensor and ground: Clean the flame sensor and verify all ground connections are tight to maintain a strong flame signal.
- Wiggle test wiring: With power OFF, gently tug on safety circuit wires (pressure switch, high limits, rollout switch) to ensure they are secure. Repair any loose or corroded connections.
- Monitor gas supply: If other large gas appliances start and stop while the heater is running, gas pressure may be fluctuating. Have a gas technician check supply pressure.
Warning: Persistent short cycling can damage components and should be corrected promptly.
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Repair Difficulty
Hard
4/5
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