Vaillant VCW 242 EH diverter moves wrong way for CH

[corkey69]

I have recently had to replace the diaphragm on both the water valve and diverter valve on my boiler. I'm fairly sure I got all the servo lines back where they should go, but now the diverter moves to the right when there is CH demand - i.e. the wrong way!

With no CH demand, the valve is central, and the DHW works just fine.

I cleaned out the servo valve, which was full of crud, and checked that all the copper pipes were clear.

Anyone got any ideas what this could be - have I inadvertantly crossed two of the servo lines, reassembled the servo valve wrong, or could it be something else?

If anyone has a photo or diagram of where all the servo lines go, that would be a great help.

Any suggestions welcome

 

[MrV]

Are you a Gas safe engineer?

 

[Bunnyman]

Swop the 2 servo pipes round, not the one at the back or the one at the front,
But the 2 at the side, there is usually a white tag with a number on the top one , and there is a number stamped on the servo I hope u didn't separate the servo, ? If u did ur probably gonna need a new one

 

[Agile]

I think its the servo valve which he opened and found full of crud !

 

[corkey69]

Thanks for the replies - the white tag is on the top one still.

The crud was more like rust deposits, cleaned out easily. Still wondering if I put that back right.

Oh well, more experiments called for before buying a new servo valve - plus a call to Vaillant on Monday!

 

[MrV]

The pipe layout is.
Servo to diverter. Top connection on servo to top connection on diverter and other pipe is bottom to bottom. If they cross, they are wrong.

 

[corkey69]

Thanks - that's how they are, but the diverter still moves right.

just found that the DHW is fine, but no CH at all - because the diverter goes right, there is no flow around the rads, if i force the valve left (v difficult) all is ok. there must be a crossed hydraulic somewhere elstime to phone Vaillant I think.

 

[Bunnyman]

Don't bother ringin Vaillant there technical is a joke an most of the engineers not trained on older models, it sound like u put the servo together wrong if ur sure the pipes r right at the servo end r u sure they r right at the divertor end as mr v has said?

 

[MrV]

Had missed that you'd stripped the servo.
Is the diverter valve moving outwards in both heating and hot water mode?
Does the cam behind the servo move when you open the tap?
If yes to both above then yes it's most likely the servo is reassembled incorrectly as Bunnyman has said, of which the ceramic internal cam is not moving.

 

[MrV]

most of the engineers not trained on older models

As far as I was aware, quite a few engineers had been doing some extra training on the older models earlier this year.

 

[corkey69]

mr.V

the valve only moves out for CH, not DHW. The cam moves for DHW, and I get hot water.

L checked that the servo is working correctly by blowing down the pipes and I am fairly sure that it is right, judging by the clean pattern on the ceramic plate inside, it is assembled ok.

I don't know if I have the pipes right elsewhere, but from the servo to the diverter are right.

thanks for the ideas, i will phone the makers today and see what they say.