08
Immergas DHW Temperature Sensor (NTC) Fault

Furnace shows 08, domestic hot water (DHW) may not function correctly or temperature fluctuates

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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

Failed DHW NTC sensor, Loose or oxidized DHW sensor connector, Scale buildup causing poor sensor contact

How to Fix / Troubleshooting

Safety: Turn off power and close water isolation valves before removing any DHW components.

Steps:

  • 1. Locate DHW NTC: On combi-type Immergas furnaces, the DHW NTC is usually mounted on the DHW outlet pipe or on the plate heat exchanger.
  • 2. Check wiring: Inspect the sensor cable for damage and ensure the plug is fully inserted into the PCB connector.
  • 3. Descale contact area: If accessible, clean any scale or debris around the sensor pocket to ensure good thermal contact.
  • 4. Replace sensor (technician or skilled DIY): Shut off cold water inlet, relieve pressure by opening a hot tap, then remove and replace the DHW NTC. Use new seals and tighten to manufacturer torque.
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Repair Difficulty

Medium 3/5

Required Part

DHW NTC Temperature Sensor
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