Riello Delayed Ignition / Combustion Instability

Furnace makes loud rumbling or booming noise at startup

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

Excessive air or fuel at light-off, Incorrect electrode position, Dirty combustion head, Oversized nozzle

Safety: Turn off power and fuel. Do not continue to operate with loud booms—risk of damage.

Steps:

Inspect and clean burner head: Remove soot and debris from the Riello combustion head and blast tube.
Verify nozzle size: Confirm the installed nozzle matches the furnace and Riello burner specification.
Adjust electrodes: Set electrode gap and position exactly per Riello manual.

Final combustion adjustments should be done with instruments by a technician.

Professional Required 5/5

Combustion Head Assembly

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