Viessmann Diverter Valve

[iloatheboilers]

Hope someone out there can help.

Having some trouble with a Viessmann (Vitodens 100 - WB1A) in that it doesn't do HW... When demanded, it duly fires up and gives the tap symbol, but then begins to heat the CH circuit. We've come to the conclusion that it's the diverter valve and are in the process of getting a replacement actuator (stepper motor / cartidge unit) for my installer to fit.

The problem we currently have though is getting the old one out. Unfortunately the inst manual doesn't give any info. with respect to this part. There are two torx screws - one either side, but after taking these out it still doesn't want to budge. Anyone have any clues?

Thanks

 

[MikeyGas]

Why don't you leave it to your installer to remove when he comes around to fit the new part?

 

[mysteryman]

Remove the two screws in the horizontal plane - they're all that hold the cartridge in. It can be very tight, but it can be levered out. Powerflush the whole system if the heating water isn't clean.

 

[iloatheboilers]

Thanks mysteryman - it eventually came out but it was far from easy... New part in and working fine (at the moment).

As an aside, while the cover was off I noticed that the ignition unit is one of the turquoise type that are spoken poorly of in other posts. Given the low cost and ease I'm thinking of having it replaced because reading between the lines people seem to be linking it to PCB failure which would obviously be very costly. Is this a valid assertion or would I be better to assume I've got an ok one as it's been working for so long. I inherited this boiler when buying the house a year ago but the evidence suggests it's been here about 5 years. The only record I can find of previous problems is split hoses - you can see the evidence of this at the bottom of the boiler case too!

 

[mysteryman]

Fit a new black ignition transformer, part no 7828522 list price £12.

 

[Agile]

As far as I recall the ones which all fail are grey.

There were a few turquoise and I have even seen a working reddish/pink one on a boiler about six years old.

If it has not failed then it sounds to me as if its not likely to so I would suggest you leave it.

While the engineer is there get him to losen the Torx screws on the ignition as they can be VERY tight. They need to be reasonably tight as one end is an earthing connection but not so tight you need to drill them out to remove.

Tony

 

[mysteryman]

If I had a Vitodens 100 type WB1A, I would change the ignition transformer for a black one without delay.