Vaillant 242 Combi (Beyond Economical Repair?)

[dfarry]

Hi all,

I have posted here a few times now about my knackered 12-13 year old Vaillant 242 Combi.

Although I still need to get someone to look at it I don't want to waste a penny on it if it really is beyond economical repair.... likewise I don't want to pay £1000 plus for a new condensing boiler plus fitting but there may be no other option.

In a nutshell... the boilers pressure relief valve seems to be sticking open, therefore water (and it appears quite rusty) is permanent leaking from the pressure outlet pipe outside.

Also the pressure is increasing so a few people here have suggested the secondary heat exchanger is leaking internally. Add to this the fact that the hot water is really just luke warm (despite a new DHW exchanger being fitted 18mths ago) it gives me the feeling that this is going to be expensive to fix.

I don't know any plumbers and feel very much in the lap of the gods on this one.... I'd appreciate if anyone here can offer a professional opinion on what they feel might be the likely cost to fix these problems please - this will be a big help and help me decide whether to bother going for the fix or replacement.

Many thanks

DAN

 

[Agile]

Do you have the plastic secondary HE in which case replace!

Is the filling loop left in place and leaking?

If its a metal HE and you really did not want to replace then we would probably charge about £240 to replace the PRV and filling valve and chemically clean the system. That should keep it going for anouter 2-3 years.

However, for about £1600 we could fit an economy 28 kW condensing boiler which would save you about 15% on your gas bill.

It will have to be replaced in the end so it may be better to do it now.

I visited this fellow in a £3M house with a massive very old and inefficient boiler. He was telling me about the new £30k car he was going to buy but when it came to the boiler he "could not afford" £2k to replace it and save £500 each year in gas bills!

Tony

 

[dfarry]

Thanks for the helpful info. Tony

I have just checked and from what I can see through the boiler housing the heat exchanger (I think it is the one).... is a large red chamber at the back...

It has the following label on it:-
W + P
TYP VKN12
41 KW 94
12 Litre

I think the filling loop is still fitted... or at least there is a braided hose with a tap midway that I can turn 90 degrees and it fills the boiler. However this doesn't seem to be leaking.... only the pipe that leads from the pressure valve is.

I note you are in London... I am in South East london - perhaps we should at least exchange mails etc?

Alas I do not live in a mansion... I drive a cheap family MPV... and i could certainly do without the expensive of a boiler at the moment.... but if it doesn't get fixed i'll be spending my time in the doghouse for a long time....suggesting "Go around your mum's then...." hasn't gone down well!

 

[ChrisR]

No thats' the expansion vessel. The secondary heat exchanger is at the lower left corner. Black plastic, or shiny and apparently made of layers.

 

[dfarry]

Hi Chris... thats the one that was replace about 18 months ago... it's a chromed thing...original was black plastic...

Cost me £200 to replace... had a year warranty and 5 year antiscale guarantee I think... externally it looks fine...

So this has heating water passing through it... but as mains water is being leaked into the heating system the pressure is increasing?

 

[DP]

I, on the other hand, would say this boiler can be repaired and will keep giving you good service for several years yet.

Problem for you is finding someone who knows how this boiler works, so they can carry out dignostics and repair. From sound of what you have written, problems are small. Sadly, you will get more boiler changer than repair people. Lot of repair people are part changer (to be avoided).

If you thing a condensing boiler is the answer to your problems, think again. What you save in fuel bills is more than wiped out when these tin cans fail if you can find someone to repair these complex appliances.

 

[dfarry]

Thanks for the comments DP,

I must admit concerns about condensing boiler reliability have been aired....louded... when I first posted on here nearly two years ago. The leaking secondary exchanger was replaced and gained us another two years of use....

That cost £200... it sounds like these problems may cost more to fix, and I'm a little bit concerned that every two years I might be paying £200 out here and there to keep the old boiler going.

I never bothered to have a annual maintenance contract buit when the boiler was serviced at the same time as the sec. heat exchanger was replaced, the fitter said everything was fine with it....I'm not sure what he checked but he definately fitted a gauge to it.

As for the cost of these boiler they are unreasonably high...or are they?... I think the manufacturers must be raking it in...or the middle men/fitters/boiler suppliers are..... does it really cost £1000 to make one of these "tincans"?

Are Vaillant a good place to start or do they just sub contract out work to people....the same people you could probably find in the Yellow Pages.

 

[corgiman]

vailliant or hepworth do have their own boys try them first, think they do fixed rate but am not sure

 

[Agile]

Is the filling loop left in place and leaking?

If its a metal HE and you really did not want to replace then we would probably replace the PRV and filling valve and chemically clean the system. That should keep it going for another 2-3 years.

However we do not go south of the River and apart from DP in Glasgow there are not many people willing to work to renovate older boilers.

Budget on about £2000 to replace boiler with something a little more powerful.

Tony

 

[dfarry]

Hi Tony...

I think the filling loop is still fitted... or at least there is a braided hose with a tap midway that I can turn 90 degrees and it fills the boiler. However this doesn't seem to be leaking.... only the pipe that leads from the pressure valve is.

£2000 is out of the question so I think I might have to go for replacement and clean option...

I'm quite competant at general plumbing...and most mechanical things... as long as I don't go near the gas... could I do some of this work myself... the secondary heat exchanger looks easy enough to remove as does the PRV.... or is this a big no no....? :s

 

[Agile]

The whole question is why the pressure is increasing.

Obviously when you open the filling valve the pressure increases. But whey you "turn it off" why do you think its actually turned off?

Remove the flexible hose and see if the valve is still leaking !!!

While you could work on the water parts of the boiler I would question if you have the necessary skills and experience to do whatever is required. Thats partly why there are few engineers who are prepared to do this work beause it requires a considerable understanding of the more detailed workings of the boiler.

Tony

 

[dfarry]

Yes good point Tony, although I have to say the pressure seems to be increasing at a much slower rate now.

The filling valve could be allowing extra water to go into the system, although it feels (and sounds) as though it is shutting off fully.

I have approached a engineer who is corgi reg'd and specialises in Vaillant boilers - he seems to know what he is talking about and feels (based on what I have told him) that and I quote from his email reply...

First, the pressure relief valve needs re-seating, or replacing (£20). Then the expansion vessel may need re-charging (£nil), then the domestic heat exchanger needs removing and flushing out/cleaning (£nil).
Basically, the boiler needs a bloody good going over, and it sounds to me as most of your problems can be sorted out on a service visit. There shouldn't be any major expense on parts as far as I can see by reading your e-mail

He charges on a fixed price rather than hourly rate so at least I will have an idea up front just how much this will cost.

I am one of these people that Part P and Part L is designed to discourage.... I am inquisitive (like to know how things work)....and if I can fix them myself - saving a few pennies is a bonus but not my main motivation. Removing the secondary exchanger looks straight forward.... four nuts I think and off she comes... but the question then is how do I first isolate the water supply (or do I just drain the whole thing down) and then once I have the thing off and in my hands what do I do with it?... I guess some simple tests such as manually filling the mains water inlet on the exchanger to check for leaks into the heating circuit might be useful. Apart from that I wouldn't know the best way to descale or clean it for example. On refitting it looks like the threads are covered with PTFE tape so I would replace that I suppose.

Filling.... well right or wrong I would just use the filling valve, take the pressure up to about two bar and the work my way around the rads to bleed the air out.
I'd continue to top up the boiler with more fresh water as the pressure drops. I'd then usually put the heating on until it was at normal working temperature and continue to bleed the rads until they were all hot and air free.

I'm sure there is probably much more to filling the system than that but basically that's what I do at the moment. It is interesting the engineer has mentioned about the expansion tank, if there is a specific procedure for "recharging" it then there is a good chance this has not been done and might be worth a try.

Thanks again Tony...much appreciated!

 

[Agile]

For the third time I think:-

"""Remove the flexible hose and see if the valve is still leaking !!!""""

What you "think" is irrelevant! Whats actually happening is !!!

Tony

 

[dfarry]

Yes I'll do that... thats no problem, I am listening to your suggestions and you may be right....... but I "think" you may not!

 

[Agile]

If the system pressure is increasing when the filling loop is disconnected then there is another of high pressure water. Thats normally a leak in the plate heat exchanger which is a relatively expensive part.

In any case, the Water Regulations require that its removed when not in use.

In the same way an airline pilot goes through a checklist before a flight I go through a checklist when inspecting a boiler. It starts with the flue because a faulty flue terminal can cause it to explode. At a later stage when opening the boiler it includes checking the polarity and earthing.

The checks are not because I "think" that any of them may be wrong but because only by checking them can I be sure they are correct and I am in no danger working on the boiler.

Tony