Termet Short Cycling / Overheat or Control Instability

Furnace short cycles: starts, runs for a few minutes, then shuts off and restarts frequently.

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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 furnace relative to load, Restricted airflow, Faulty thermostat placement, High-limit thermostat cycling on Termet heat exchanger

How to Fix / Troubleshooting

Safety: Turn off power before removing panels.

  • Check filters and vents: Replace dirty filters and ensure all supply/return vents are open.
  • Thermostat location: Make sure the thermostat is not near heat sources or in direct sunlight. Relocate if necessary.
  • Observe operation: Watch the burner through the inspection window. If it shuts off while the blower continues, the high-limit may be tripping due to overheating.
  • Adjust fan settings: If accessible, increase blower speed to improve heat removal from the exchanger.

Persistent short cycling may indicate sizing or ductwork issues that require a heating professional to evaluate.

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Repair Difficulty

Medium 3/5

Required Part

High-Limit Thermostat
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