vcw gb 221 h vaillant combi compact help

[cam2]

hello, I have a vaillant combi compact. which is quite old - don't know how old. the heating works fine but I have no hot water.

The problem has been intermittent and getting progressively worse over last few months.

When the boiler is in hot water only mode the pilot light is lit and you draw hot water only cold comes out and the main burners do not fire.

it started with not getting hot water down stairs in the kitchen if I drew hot water in the kitchen I only got cold, however could get hot upstairs sometimes immediately sometimes I would have to wait.

When heat and hot water selected the burners light and the radiators warm immediately. however when I try to draw the hot water the burners switch off until I turn the tap of and then need to switch all off and on again some time later to get rads back on. (I don't know if this is meant to happen or not)

Now no hot water anywhere.

I have had a new diverter valve fitted (from another old boiler as have a spare in the shed and the diaphragm was sound). (by a gas safe fitter who got me the spare boiler taken from a house in full working order)

I have read a number of other post but think I have just confused myself. any advice would be appreciated. thank you.

 

[ChrisR]

Iirc they stopped about 1996. They're a little more complex than the current combis and a lot of indpendent repairers wouldn't know them well. There's a Servo valve and hydraulics that block, apart from the diaphragms etc.
Usually fixable and parts are still around though.
Expect to have to make a lot of phone calls to find someone willing and competent to work on it.

 

[cam2]

Thank you very much for response will try to find out where the servo valve is and if I can get one . thanks again

 

[gas112]

look at diaphragm in water section as opposed to messing with divertor valve

 

[Bunnyman]

Yea water valve probably, the divertors rarely fail