Vaillant VCW-Sine 18 T3WF H - Various issues

[Lashed]

Hi All

Would really appreciate some help...I have one of these babies, it's 25+ years old and never really given me any problems.

Heres whats happening...

1) one radiator has been cold for the last couple of years. Not really a problem as it's in a box room that isn't used. Tried bleeding but no joy.

2) Last couple of weeks the hot water has been just luke warm...just about hot enough to have a wash with without mixing in any cold water. However when the rads are on, the hot water gets hotter (ut not super hot)

3) pressure sits about .5. When re-pressurized to just below two, it slowly seeps back to .5 after an hour or two.

4) When the "Constant hot water switch" (the one to the the right of the on/off switch) is turned on, nothing happens...ie the boiler does not fire up.

FYI, the 1-8 dial that should be controlling the water temperature is at 8. And central heating seems to work fine apart from the 1 rad mentioned above.


Is it time to retire her ?

Any help would be appreciated

Thanks
Ash

 

[Agile]

It sounds as if the diverter valve is failing!

The expansion vessel may need recharging or be failing ( See FAQ ).

The 1-8 dial is only for the heating temperature and should give a variation of the rad temperature.

Your non working rad may have a jammed valve or blocked feed pipe.

These boilers are old, still reasonably efficient, but parts are starting to be difficult to find. The number of engineers who understand them and will deal with issues is now very few. Part of the problem is that they all have multiple faults and need a complete overhaul whereas owners expect a cheap simple repair and never bother to get them serviced as they are very tolerant and just keep on working for years without servicing.

Tony

 

[mickyg]

Unlikely to be the diverter valve, they are extremely reliable.
The hydraulics will need checking, ideally by someone who knows them well. The water valve might not be giving full travel, the servo valve could be faulty, or the connecting tubes could be blocked. All the components likely to fail on this appliance are still available. If you have the original domestic heat exchanger this could be full of scale by now.
As tony said, expansion vessel probably needs recharging, prv cleaning/changing. If serviced regularly by a good engineer there's no knowing how long these things will last. Unfortunately everytime I see one and ask the question "when was it last serviced?" the answer is usually never. Their reliability is in effect their downfall, as too many people still don't think their boiler needs servicing until it breaks down

 

[Lashed]

Thanks guys.

Is re-pressurising the expansion vessel on one of these something a novice can attempt? I've read the FAQ section on these and it seems fairly straight forward.

 

[mickyg]

yes you should be able to do it yourself, Look in the FAQ on this site. The schraeder valve for the exp vessel is at the bottom of the vessel slightly off centre to the left. If you remove the LH side panel and have reasonable access you should see it.

 

[namsag]

Yeah its straight forward better if boiler is empty though

 

[Agile]

Unlikely to be the diverter valve, they are extremely reliable.

I think you must be thinking of the later model!

This is the one with the wax element which often fails or the valve jams. The element is no longer officially available on its own and is now supplied as the whole assembly at about £165.

Tony

 

[mickyg]

yes tony, sorry yes, I was working on a 221 the other day and for some odd reason I had it in my head

 

[Drees113]

My boiler has the same issues described by Lashed a year ago (Agile and Mickg seemed to know there way round said boiler), lack of hot water, fading pressure, but radiators okay. General sense of the blog and my heating engineer is that it is diverter valve and the expansion vessel may need recharging.

Does anyone know whether the parts are still available and where I can get a manual or fault board so my engineer can do the work.

thanks
David

 

[kevplumb]

i know where you can get a copy of the manual

do you know how to put an e mail addy in your profile

 

[Drees113]

Have added e-mail

David

 

[kevplumb]

sent


should keep you out of mischief for a while

 

[Agile]

Drees, you seem to be intending to fix the boiler yourself.

There are many aspects to be checked and some are gas. So I would recomend you get a competent engineer who will know where to get what parts are still available.

Tony

 

[Drees113]

No - will not attempt myself, just sourcing manuals etc for my heating engineer

thanks for concern

David

 

[Agile]

I would be surprised if any competent engineer did not either already have one or knew what to do without it.

All I have ever seen for this model is a cheque book sized mini booklet giving very little information.

I could not find anyone who understood them so I had to work it out for myself.

Tony