Lochinvar Short Cycling / Control Oversensitivity

Boiler short cycles, turning on and off frequently with small temperature changes

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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, incorrect differential settings, low water volume system, improper primary/secondary piping

How to Fix / Troubleshooting

Safety first: Adjust only user-accessible settings unless you are a trained technician.

  • Check thermostat and setpoint: Ensure thermostats are not located near heat sources or drafts. Adjust boiler differential (if available) to a slightly wider range to reduce cycling.
  • Verify system flow: Confirm all valves are open and pumps are operating to maximize system water volume engaged with each cycle.
  • Use buffer tank (professional): In very low-mass systems, adding a buffer tank can reduce cycling; this requires professional design.

Professional help: A technician can optimize control parameters and evaluate if the boiler is significantly oversized.

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Repair Difficulty

Medium 3/5
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