Protherm Excessive Flue Noise / High Gas Rate

Furnace is very loud at the flue terminal outside

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

Over‑firing due to incorrect gas valve setting, Partially blocked flue causing high velocity, Loose flue terminal components, Fan running at maximum speed due to sensor fault

How to Fix / Troubleshooting

Safety first: Turn off power and gas if noise is accompanied by smell or visible damage.

Step 1 – Inspect terminal: Ensure the flue terminal is intact and firmly attached.
Step 2 – Check for obstructions: Remove any debris around the terminal.
Step 3 – Technician adjustment: A technician should verify gas input and fan modulation, correcting any over‑firing or sensor issues.

Repair Difficulty

Hard 4/5

Required Part

Concentric Flue Kit

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