E27
Weishaupt Room Control / Bus Communication Fault

Boiler indicates E27, room thermostat or bus communication fault with Weishaupt room controller.

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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

Broken bus cable to room controller, Incorrect polarity on bus terminals, Faulty Weishaupt room unit, Interference from external wiring

How to Fix / Troubleshooting

Safety first: Turn off power before altering control wiring.

  • Check room controller: Ensure the Weishaupt room unit is powered (if applicable) and its display is active.
  • Inspect bus wiring: Verify that the two-core bus cable is correctly connected to the designated terminals at both boiler and controller, observing polarity if required.
  • Check cable integrity: Look for damage along the cable route. Test continuity with a multimeter.
  • Reduce interference: Avoid running bus cables parallel to mains cables over long distances.

When to call a professional: If communication cannot be restored, the room controller or boiler control may need replacement.

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Repair Difficulty

Medium 3/5

Required Part

Weishaupt Room Controller
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