Smell gas? Leave the property and call the National Gas Emergency line on 0800 111 999

F.20

Glow-worm fault code

Glow-worm F.20: safety switch-off: overheating temperature reached

Engineer only

The boiler reached its overheating limit and shut down for safety.

What you can safely do

There is nothing you can safely do yourself with this one. Leave the boiler off and book an engineer.

Find a Gas Safe engineer near you Opens the official Gas Safe Register search.

Applies to: Energy range, Betacom A range. Codes can differ between models, so check your manual.

From Glow-worm's own fault tables. Your model name is usually on the front of the boiler or in the user manual.

Model	Meaning	Causes listed for engineers
Energy range	Safety switch-off: overheating temperature reached	Incorrect earth connection, flow or return sensor defective or loose, ignition discharge problems
Betacom A range	Overheating fault	Not listed

Should I keep resetting F.20?

No. It is a safety shutdown. Book an engineer.