My boiler keeps on locking out showing f.22 or f23. I have had two 'experts' look at it, one changed Almost every part, including the motherboard other than the pump (logic dictates that's the fault?). The man from vaillant pretty much said either it needs a power flush or just change the whole thing! It comes on fine, the heating warms up a little and then it shuts down, the hot water is not working other than a pathetic short burst of tepid water and then we are back to ice cold, it's been three weeks, and I'm starting to smell! The boiler. Can't be more than 5-7yEars old, do I really need to freeze or buy a new boiler? This is ridiculous, please help!!!

Eskimo pete, November 2010

I had a similar problem a couple of years ago and it turned out to be a faulty diaphram on the gas supply meter. It was losing pressure for the mains gas supply and causing the boiler to effectively run out of gas and lockout f22,23

Justin littlechild, January 2011

The electronics in these things are complicated and have various built in fail safes. One little one that shuts the boiler down is the air pressure switch (very top right behind shield right of fan) This is of a flimsy construction designed to prevent the fan from burning if it fails ie No air pressure from fan and system closes down. However, the electronics have to bypass this on start up to allow fan to start up. This part was intermittently faulty and caused all sorts of head scratching. If you simply pull off one of the two wires (when units electric is switched off) and fire it back up so if it stays on you've cracked it if not at least it's not that. IMPORTANT, if it is the problem get a new part fitted ASAP. Remember this part is used as a "fail safe" device to prevent fan from catching fire!!!!!!!

Billy, December 2010

Hi there had a problem like this. The pump worked fine until it started to get warm then it would stop. The Boiler then sounded like it was going to blow up. Fitted new circuit board temperature sensors.never thought pump was faulty as every time i checked it spun ok cold,I now have plenty of spare parts. Good luck.

Ryan, November 2010

I guess this should have been under the heading of home heating systems.

Eskimo pete, November 2010