EHC
Short Cycling
Boiler cycles on and off rapidly without reaching set temperature.
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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
Oversized boiler for system, Incorrect control settings, Blocked or closed radiators, Faulty temperature sensor or PCB logic
How to Fix / Troubleshooting
Safety: Short cycling can reduce boiler life; address the cause promptly.
User checks:
- Ensure enough radiators are open to dissipate the boiler’s output.
- Check that the room thermostat is not located too close to a heat source or the boiler.
Engineer checks:
- Review boiler output settings and, if possible, range-rate the EHC boiler to better match the system.
- Check flow and return NTC sensors for correct readings.
- Verify pump speed and system balancing to ensure adequate flow.
Optimising controls and flow usually reduces short cycling and improves efficiency.
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Repair Difficulty
Medium
3/5
Required Part
Primary Flow NTC Sensor
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