Vaillant VCW GB 242 EH : Water section issues *URGENT* pls

[fastbike]

Excuse the "urgent" but I'm hot-water-less :

The hot water supply has grown increasingly intermittent on my combi until now it rarely works. Central heating is fine.
The cam by the servo valve isn't moving reliably, insufficient to operate the DHW microswitch. If the cam is "encouraged" manually then the diverter valve does operate properly and hot water happens.

The water flow rate seems unchanged so I don't think that the secondary heat exchanger is blocked.

At the moment, I'm tending to suspect the water section being scaled up or its diaphram faulty (Can anyone confirm this hypothesis?)
I'm tempted to replace the entire water section module because that looks most straightforward, but most suppliers seem to be suggesting the type 011299 which looks slightly different underneath. I think that it also may not have a connection for the DHW expansion vessel fitted in my boiler.
Can anyone confirm that the updated valve 011299 is compatible?
How does it cope without the DHW expansion vessel? Do I leave that disconnected?
Advice most gratefully received.
Many thanks !
- Steve

 

[fastbike]

OK, well I've got this complete water section ordered anyway.
Can anyone give any fitting tips ?

Thanks.

- Steve

 

[bengasman]

More likely than not, the described problem is due to poor installation and/or lack of proper maintenance causing excessive corrosion residue to stop the boiler from working properly.
You probably need the entire system cleaned.

 

[fastbike]

More likely than not, the described problem is due to poor installation and/or lack of proper maintenance causing excessive corrosion residue to stop the boiler from working properly.
You probably need the entire system cleaned.

Well, it's had the recommended routine maintenance but I wouldn't be surprised if the whole system does need a good clean. Good idea!
On the other hand, after around 20 years of continuous service in a hard water area with no previous breakdowns, I think it must be one damn robust boiler!

 

[Bunnyman]

U did right getting complete valve 011299 is correct just ignore the 4mm pipe don't try an connect it there is no need turn off mains open hot taps then undo the 3 30mm nuts an the 24mm one the the 8 mm to expansion vessel the unit is held in place with a grub screw just above in the centre,b very careful undo in this use some wd40 if u round it off which sometimes happens then jobs a right bastard an u will need bracket 086462

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[Slugbabydotcom]

Excuse the "urgent" but I'm hot-water-less :

The hot water supply has grown increasingly intermittent on my combi until now it rarely works. Central heating is fine.
The cam by the servo valve isn't moving reliably, insufficient to operate the DHW microswitch. If the cam is "encouraged" manually then the diverter valve does operate properly and hot water happens.

The water flow rate seems unchanged so I don't think that the secondary heat exchanger is blocked.

At the moment, I'm tending to suspect the water section being scaled up or its diaphram faulty (Can anyone confirm this hypothesis?)
I'm tempted to replace the entire water section module because that looks most straightforward, but most suppliers seem to be suggesting the type 011299 which looks slightly different underneath. I think that it also may not have a connection for the DHW expansion vessel fitted in my boiler.
Can anyone confirm that the updated valve 011299 is compatible?
How does it cope without the DHW expansion vessel? Do I leave that disconnected?
Advice most gratefully received.
Many thanks !
- Steve

Well I think you are bang on with your DIY diagnosis.

I rarely fit new diaphragms to these now as sometimes internal parts are de-zincified [brass parts disintegrated]

I have fitted the watersections now available and you are right. There is no connection for the shock arrestor / mini exp vessel.
These are the ones with the red wheel for temp adjustment on the front which no one uses after they set it to max.
So far I have never reconnected another mini EV and never had any problems. If you do get any problems you will know where to look. The problems you might expect to get are noisier operation when you turn taps off and leaks or seals blowing out on taps / mixers. You are more likely to get a problem if there is a check valve between the main stoptap and the cold supply to the boiler.

 

[fastbike]

Just an update and some observations that might be useful to people:

I managed to get the complete new water section quickly from heatingspares247.com Fitting this was quite easy and now the hot water works fine.

CAUTION: I could have ordered the part from a couple of other web sites, but in two cases when I phoned them and asked if they could guarantee next day delivery, it became clear that they did not actually hold stock, but "could get the part in a couple of days" if they received the order online.
So buyer beware!

Many thanks to everyone that gave me advice.

- Steve