My Vaillant boiler is showing F.28. The green light is flashing and the red light is on all the time. I have pressed the 'flame 'button and the boiler appears to fire up and then seems to struggle. A couple of times its started working and I've been able to draw a bath but now it won't work at all! Please help I need to wash my hair!!!

Alison, July 2009

I'v got an 824E with SAME problem - boiler goes to lock -out (red light on ) fault code F28. Manual spouts on about gas related problem. HOWEVER the problem ONLY occurs when in HOT WATER MODE ONLY. no problem in water & heating mode. Personally (and having spoken to a few boiler engineers too) conclusion seems to point towards either a faulty DIVERTER valve OR fault on printed Circuit Board.
Trouble is , diverter valve costs around £100 and the board around £200 !!!

Mark, July 2009

It means that it has failed to ignite. Could be a problem with gas supply, gas valve, ignition or air / gas ratio.

Ian, July 2009

The pressure guage is now in the red when it was in the green??

Alison, July 2009

to be honest I don't know what model it is - can't find a label? Thanks for the advice, If its those things what should I do?

ALison, July 2009

its the pump i think is it the eco tec model?

Nathan, July 2009

fan air presure switch problem

steve, July 2009