Component repair
Fan and air pressure switch faults
Fan-related codes are among the most common lockouts we see. The fan proves it can clear the combustion products before the boiler will light, so anything interfering with that proof — the fan itself, the sensing tubes, or a blocked flue — stops ignition.
For: Boilers locking out with fan-related codes
Not always the fan
Perished or water-logged sensing tubes give exactly the same code as a failed fan at a fraction of the cost. So does a partially blocked flue or a terminal in a sheltered corner recirculating flue gases. We check pressure at the switch and inspect the flue before condemning a fan.
Checked on the visit
- Fan current draw and bearing condition under running load
- Sensing tubes inspected for splits, kinks and condensate
- Flue integrity and terminal position assessed
- Air pressure switch operation verified against manufacturer figures
Frequently asked
- The fan runs but it still locks out — why?
- Running isn't the same as producing the required pressure differential. Worn bearings drop speed enough to fail the proof without stopping.
- Is a noisy fan urgent?
- It's a warning rather than a hazard. Bearings usually give weeks of notice, so booking a planned repair avoids an emergency.
- Are parts available for older models?
- For mainstream Worcester, Vaillant and Ideal units generally yes. Obsolete parts are where replacement starts making sense.
Test before you buy a fan
Fans aren't cheap. A proper pressure test at the switch avoids fitting one to solve a five-pound tube fault.
Related solutions
Core services
Where we cover
Worcester Bosch Accredited · 10 Year Guarantee*
New Worcester boiler with a 10 year guarantee*
Free no-obligation quotes for installation, servicing & repairs across BA & BS postcodes.