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

I went to a WB 28cdi yesterday, same fault, dhw light flashing rapidly. This is a fault code for air flow sensor. If you are not corgi/gas safe then DON'T touch it....call the pro's in! It is a legal requirement for anything to do with combustion components! Anyway, I managed to kick this boiler into action, if only for a brief moment. The fan sounded like it was gonna fly out of the casing, and squeaking! Bearings! Bingo! The fan was weak thus not giving the flow sensor the correct air pressure. So, this boiler needs a new fan, my thoughts are, if the fan is tired, for the price of it, I may as well replace the pressure switch at the same time. To gain access to the fan, you will have to break the seal on the cover, this seal needs to be replaced!! Anyway, once all the parts have been replaced, checks need to be made! Ie, with gas flue analysers etc... So this is not for the DIY enthusiast! Although you think you may be saving a couple of quid, but a couple of quid ain't worth saving if this is not done correctly and putting lives at risk!!! By not having it done by a qualified engineer. Boiler runs like a dream.

Simon, December 2012

Same problem with our WB 28CDI. Have had many boiler specialists come to visit, and now they won't even return our calls. British Gas say there is nothing wrong with boiler - but agree it doesn't work. Boiler is 11 years old.

If we change the whole system, what guarantee do we have that the same problem doesn't happen again?

Damsel, March 2011

I have an identical problem with my water. I work in a boiler spares shop and I have spoken to more than 20 engineers and they all agreed it was a P.C.B. problem, but....

I have replaced the P.C.B. but there was no change. I have checked the air pressure sensor and the sensor tubes, I have tested and visually inspected the fan for correct operation and I have checked the flue for blockages. The temperature sensors all work correctly and I replaced the plate heat exchanger and flow limiter.
I may well replace the DHW diaphragm and possibly the microswitch but I cant think of anything else i can do.

The heating also gets up to temperature and cuts out too. I have another engineer coming out to investigate further for me. If he has an answer to the problem i will post it to you all here.

Alun, January 2011

Im a gas safe engineer and specialise on Worcester boilers. Even if your boiler is 10 years old its still worth fixing. Its not likely to be a fault that is a diy fix, appart from looking at the flue there is nothing you can do, look dont touch, its illegal and not safe. Go on call worcester bosch and they will give you details of a specialist in your area.

Jason

Jason Clayton, October 2009

Yes the flashing water neon is an airflow fault, usually the air pressure switch, but can be the air pressure tubes, blocked flue, restrictor ring in flue, fan, case seals, chocked heat exchanger etc etc, no simple diy solution - call an engineer.

Dave - BG, February 2009

Hi Michael,

yes the same thing happens when I put the heating on. I haven't called out an engineer yet, just wondered what I could try myself before going to the expense of an engineer. The boiler is apparently 8 years old, judging by the service history that I've got. Obviously, I don't want to replace the boiler unless absolutely necessary if a small repair charge can fix it. As your boiler is doing the same I imagine that it must be a relatively common fault. Anyone any ideas?

Wendy, October 2008

Wendy, Exactly the same happens to me. However, mine also happens when I put the heating on, not just the hot water. Did you call out an engineer, and if so what did he say? My boiler is 10 years old so I'm not sure it is worth fixing. How much was your repair?
Michael

Michael, October 2008