Danfoss Flue Resonance / Draft Imbalance

Furnace operates but makes a rumbling or roaring noise through the flue

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.

Possible Causes

Improper flue sizing, loose flue supports, excessive draft, partially blocked flue creating turbulence

How to Fix / Troubleshooting

Safety first: Turn off power before working on the flue. Use proper ladders and fall protection if accessing roof vents.

Steps:

Inspect flue path: Check for loose sections, missing hangers, or contact with building structure that can transmit vibration.
Look for obstructions: Examine the flue termination for bird nests, leaves, or ice buildup. Clear any obstructions.
Secure flue: Add or tighten supports to reduce movement and resonance.
Consult a technician: Persistent rumbling may require draft measurement and flue redesign by a professional.

Repair Difficulty

Hard 4/5

Required Part

Flue Pipe Assembly

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