Delta Dore
No Heat Demand Output
Thermostat powers on but does not call for heat; boiler or receiver never activates even when setpoint is higher than room 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
Incorrect operating mode (OFF or Frost protection), Misconfigured system type, Faulty relay output on thermostat or receiver, Broken control wire to boiler
How to Fix / Troubleshooting
Safety first: Turn off power to the boiler and receiver before touching wiring.
- Check mode: Ensure the thermostat is in Comfort or Auto mode, not OFF or Frost. Increase setpoint several degrees above room temperature.
- Observe receiver: If using a Delta Dore RF receiver, check if its LED changes state or you hear a relay click when demand should start.
- Verify wiring: Confirm that the thermostat or receiver relay contacts are correctly wired to the boiler’s control terminals.
- Test relay: In installer mode, some models allow a manual output test. Activate it to see if the boiler responds.
If the thermostat indicates demand but the relay does not switch, the output stage is likely faulty and the receiver or thermostat must be replaced.
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Repair Difficulty
Medium
3/5
Required Part
Delta Dore RF Receiver or Thermostat Relay Output
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