Immergas Insufficient Heating Output / Undersizing or Modulation Issue

Furnace runs but radiators remain lukewarm; the house does not reach the 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

Boiler maximum power limited in parameters, partially blocked primary heat exchanger, circulation pump running at low speed, air in system reducing flow.

How to Fix / Troubleshooting

Safety: Allow the system to cool before bleeding radiators or opening any components.

Steps:

  • 1. Check thermostat and setpoint: Ensure the room thermostat is set high enough and in a suitable location (not behind curtains or near heat sources).
  • 2. Verify radiator valves: Make sure thermostatic radiator valves are open in rooms that are cold.
  • 3. Bleed radiators: Remove trapped air starting from upper floors. Re-pressurize the system as needed.
  • 4. Check boiler settings: On the Immergas control panel, verify that the heating set temperature is not set too low and that any "eco" or reduced power modes are appropriate.
  • 5. Technician tasks: Check pump speed setting, clean the primary heat exchanger, and verify that maximum heating power is correctly configured in installer parameters.
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Repair Difficulty

Medium 3/5

Required Part

Circulation Pump
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