Ideal F3: fan and flue pressure switch mismatch

An F3 airflow fault — the facts that change the job

• Check the outside flue terminal is clear of nesting or debris
• A partially blocked terminal loads the fan enough to trip F3
• Worn fan bearings fail the pressure switch test intermittently
• The pressure switch itself is a wear item on older appliances
• This is a safety interlock, not a component to bypass

An F3 airflow fault explained in plain terms

Outside, check the flue terminal for bird nesting, ivy growth or accumulated debris, since a partial block loads the fan enough to fail the switch test even with sound components. Inside, worn fan bearings and a failing pressure switch itself both produce the same code as they age. Because the fault sits on a safety interlock, engineers verify with the flue clear and accessible rather than guessing from the fascia alone.

Where we deal with this

• Bear Flat (BA2) · 8 mi
• Shepton Mallet (BA4) · 7 mi
• Nailsea (BS48) · 14 mi
• Bruton (BA10) · 13 mi
• Oldfield Park (BA2) · 8 mi

Questions we get asked

Can I check the flue terminal myself?

A visual look from ground level is fine; clearing anything on the terminal or inside the flue is engineer work.

Does weather affect F3?

Yes — strong wind directly onto some flue positions can occasionally interfere with the pressure switch reading.