Vaillant ecomax hot water cuts out

We have a Vaillant combi boiler, sorry I don't know what model it is hit if that's important I can find out. It is about 5 years old.

For quite a while now there's been a problem with the hot water, in that it will just decide to not work when you turn on a tap or shower. There is no error code, it just doesn't seem to register that we want hot water. The only way to remedy it is to reset it. It then seems to work again, until recently when it will work for a minute or two before cutting out again, when the water becomes not stone cold, but I certainly wouldn't call it warm either.

We've had the plumber round, who has checked the heat exchange, which was fine but cleaned it anyway. He also replaced something else as well, but again sorry I can't remember what it was, if you need to know, ask and I'll find out. Occasionally after multiple resets it displays f22 error code, which is low pressure, and obviously rubbish as the pressure guage read fine.

One other thing... A little while ago one of the rubber pipes inside burst, throwing hot water over everything. We had it replaced and cleaned and it does work in every other respect, like the timer and central heating.

Any suggestions would be greatly appreciated, and sorry the explanation was so long!!

Hi,does the f22 fault code happen on heating as well ? I believe on these boilers when the pump runs the pressure sensor looks for a .3bar rise. Which is a common fault. Either dirt in pressure sensor or expansion vessel needs charged. Also when you run a hot tap does the boiler show it has sense a tap is open?ie trys to fire?

Thanks for your reply.

We never see the f22 message, or certainly haven't for a number of years, on the central heating, no. The only time we see it is when we frantically try to reset it due to the hot water not working. I'll let the engineer know though when he comes so he can check those


Yes, it does. It just doesn't fire up sometimes, then other times it shows the tap and fires up, we get hot water for maybe a minute, then the flame goes out and the hot water stops, although the picture of the tap stays illuminated.

Migth be worth a try as i havent work on this type of boiler but if there like the glowworm which vaillant make theres a filter fitted in the housing beside the rubber hose's which collect sludge. Which will give these symptoms. Also the engineer should be able to enter the installer menu on boiler which which will tell him the boiler flow temperature etc

U really need the model, everyone is guessing? How can we advise if we don't know!