Immergas Overshoot Due to Incorrect Control Parameters

Room temperature overshoots setpoint by several degrees before boiler turns off

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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

Thermostat installed in poor location, Control algorithm set to on/off instead of modulating, Cycle rate or hysteresis too wide, Boiler minimum power too high for system

How to Fix / Troubleshooting

Safety: Only adjust installer parameters if you understand their effect; otherwise consult a technician.

  • Step 1 – Check location: Ensure the thermostat is on an interior wall, away from drafts and heat sources.
  • Step 2 – Adjust control mode: In advanced settings, select modulating or proportional control if supported with your Immergas boiler instead of simple on/off.
  • Step 3 – Reduce hysteresis: Decrease the temperature differential (e.g., from 1.0 °C to 0.3–0.5 °C) if adjustable.
  • Step 4 – Optimize boiler settings: Have a technician adjust boiler minimum output and flow temperature curves to better match the heating system.
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Repair Difficulty

Medium 3/5
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