Danfoss Cold Start Issues / Marginal Ignition or Fuel Supply

Furnace occasionally fails to start on very cold mornings but works later in the day

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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

Thickened heating oil at low temperature, weak ignition transformer, marginal gas pressure at peak demand, stiff motor bearings

How to Fix / Troubleshooting

Safety first: Do not repeatedly reset a burner that fails to ignite. Unburned fuel can accumulate.

Steps:

  • Oil systems: Ensure the oil tank and lines are protected from extreme cold. Consider using winter-grade oil or additives as recommended by your supplier.
  • Service ignition system: Have a technician test and, if needed, replace the Danfoss ignition transformer and clean electrodes.
  • Gas systems: If gas pressure drops during peak usage, your gas supplier may need to check the service line and meter.
  • Lubricate or replace motors: Older motors with stiff bearings may need lubrication or replacement.
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Repair Difficulty

Hard 4/5

Required Part

Danfoss Ignition Transformer
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