Vaillant Combi CH problem (HW ok)

[Edev]

Hi,

We have a Vaillant Combi GB242E or 282E boiler (that's from the manual, can't find the model on the actual unit).

The hot water is fine, but the Heating isn't.

I did a quick search on here and found http://www.diynot.com/forums/viewtopic.php?t=14554 but it's a slightly different problem.

When the heating is turned on, the pump runs, but the burner never fires. If, whilst the heating is on (pump running), I turn a hot water tap on, the burner will fire, and the radiators will start to heat up.

However, as soon as the HW is turned off the burner shuts off, and the radiators go cold again.

Initially it only did this intermittently, but turning it back on after summer, it now does this all the time.

Any thoughts greatly appreciated!

Thanks,

Ben.

 

[pipe]

most likely reason is diverter valve sticking/faulty

 

[chrishutt]

Vaillant VCWs incorporate a fairly sophisticated hydraulic control system, which includes a servo valve, diverter valve and differential pressure valve. Basically, a pressure differential is created by the pump and is transferred via microbore tubes to the servo valve and then to the diverter valve.

Failure of the diverter valve might therefore be caused by a fault elsewhere (e.g. servo valve, blocked tubes), so "pipe" is making the classic error of failing to understand the integration of the various components. This system is unusual and so you need to find an engineer who is familiar with the operation of this boiler.

 

[Flameout]

It might be 6 years later but I'd like to know the result of the problem as I now have the exact same problem with the same boiler !!

 

[Flameout]

I can't count.....it's only a mere 5 years since last post give or take a few weeks !! )

 

[Agile]

The design of early Vaillant has not changed so all the advice given is still relevant.

The only think that has changed is that Chris Hutt sadly died during May this year.

I expect its the black thing just above and to the left of the pump.

Tony