F17 error, furnace fails to ignite or burns with unstable flame

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

Insufficient gas inlet pressure, Blocked gas filter in Glow-worm gas valve, Incorrect gas rate setting, Partially closed gas isolation valve

Critical safety: Only a Gas Safe engineer may work on gas supply and combustion settings.

Basic user check:

Confirm that the gas meter emergency control valve is fully open and that other gas appliances work.

Technician steps:

Measure gas inlet pressure at the appliance with all appliances running; compare with specification.
Check the gas valve filter for blockage and clean or replace as required.
Verify burner pressure and adjust gas valve settings according to Glow-worm commissioning instructions.
Investigate upstream supply issues if inlet pressure is low.

Professional Required 5/5

Gas Valve Assembly

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