Danfoss Ally Underfloor Heating Not Heating

Underfloor heating remains cold even though the Danfoss Ally thermostat calls for heat.

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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

Actuator on manifold not opening, No power to actuator, Mixing valve or pump not running, Air in underfloor loops

How to Fix / Troubleshooting

Safety first: Turn off power before working on manifold wiring. Water in the system may be hot.

Steps:

  • Check actuator status: When there is a heat demand, verify that the corresponding manifold actuator opens (indicator ring or pin moves).
  • Verify power: Use a multimeter to confirm that the actuator receives the correct voltage when the thermostat calls for heat.
  • Check pump and mixing valve: Ensure the underfloor heating pump runs and the mixing valve is not stuck closed.
  • Bleed loops: If some circuits are cold, bleed air from the underfloor loops according to the system manual.
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Repair Difficulty

Hard 4/5

Required Part

Underfloor Heating Actuator and Pump
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