Navien
Short Cycling / Control or System Imbalance
Boiler short cycles (turns on and off frequently) during heating
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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 load, Incorrect minimum firing rate settings, Poor system water volume, Misplaced temperature sensors
How to Fix / Troubleshooting
Safety first: Turn off power before adjusting internal controls or wiring.
- Step 1 – Check thermostat settings: Increase the thermostat differential or cycle rate if adjustable to reduce rapid on/off calls.
- Step 2 – Verify sensor placement: Ensure supply and return sensors are properly attached and insulated from ambient air.
- Step 3 – Increase system volume: If the system has very small water volume (e.g., small radiant zones), consider adding a buffer tank to increase volume and reduce cycling (professional installation recommended).
- Step 4 – Adjust boiler parameters: A technician can adjust minimum firing rate and anti‑cycle timers in the Navien control menu to better match the system.
Persistent short cycling can reduce efficiency and lifespan; have a hydronic specialist evaluate the system design.
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Repair Difficulty
Hard
4/5
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