We have recently moved into a house with a Worcester 28CDI boiler. I've downloaded the instruction manual from the internet and for past few months everything working fine. However, when a hot water tap is turned on we get hot water for a few minutes and then the airflow fault light flashes and no more hot water. The light resets itself after a few minutes and we can get hot water again for a few more minutes until the light starts flashing again. I've checked the flue and all seems clear, but is there anything else that I can check simply and easily before calling out an engineer?

Wendy, October 2008

We are having the same problem and I have been told its the fan that needs replaced.

Alan, November 2008

Hi Mr Knowitall. The boiler is firing up, both central heating and hot water, it just isn't staying on. I think you are right that it may be the fan, as I can't hear it working as it would do normally, hadn't thought to actually listen to the noise the boiler was making.
Ok, next dumb question, where is the fan? I've taken the from casing off and can't see anything fan like (have switched off electricity and gas to the boiler)

Wendy, October 2008

it cannot be related to the pessure switch or tubes that connect to the flue fan if it was the boiler would not fire up as you say

mr knowitall, October 2008

the other possibility may be the exhaut fan itself it may need cleaning or it may be sticking as it heats up sometimes all it takes is a tiny squirt of wd40 on the bearings. alternatively you may need a replacement fan unit.the fan operates a pressure switch which wil shut off the gas valve for safety reasons when the air pressure is not sufficient.

mr knowitall, October 2008

air presure switch or small tube connected in flue & onto air pressure switch blocked

gary, October 2008