Vaillant VCW 242/282 Diverter Valve question

[NotTheRedWire!]

I am just about to attempt a DHW heat exchanger replacement on the Vaillant VCW 242/282 combi for the newer 'sardine can' type. I have been told to replace the disc in the diverter valve if I do but the heat exchanger kit doesn't include one and I was wondering whether this is necessary and if so where to find the replacement disc.

Any suggestions (apart from a new boiler) are appreciated.

Thanks

 

[kevplumb]

I am just about to attempt a DHW heat exchanger replacement on the Vaillant VCW 242/282 combi for the newer 'sardine can' type. I have been told to replace the disc in the diverter valve if I do but the heat exchanger kit doesn't include one and I was wondering whether this is necessary and if so where to find the replacement disc.

Any suggestions (apart from a new boiler) are appreciated.

Thanks

get the prop h ex kit then

 

[undercover]

Yes it is necessary.

Hope you realise that replacing the H/E on one of these boilers is not for the faint hearted!!

Good solid boiler the VCW - but getting on in years now

 

[NotTheRedWire!]

I was told that this was the proper kit. Any ideas whether the disc is available separately?

 

[Gasguru]

Buy the Vaillant kit - for such a lot of work you want a guaranteed result.

Perhaps the diverter refurb kit may contain the disc.

 

[NotTheRedWire!]

I asked the guy at ezypart.co.uk and they said it was the vaillant, perhaps i've been mislead here.

Any idea how much the vaillant kit retails for?

 

[Dan Robinson]

if it doesn't have the disc, it is not the right kit.

Did a couple about a year ago - they all had the disc.

 

[chrishutt]

Just consider why the disc should be changed in the first place, then you can make a judgement about whether to do it. Even when the disc is included in the kit I doubt whether many repairers bother to change it 'cos it's a lot of extra work to dismantle the diverter valve.

The original diverter valve disc has grooves in the facing on one side. These act as a by-pass to allow a small flow through to the DHW HEX when the CH is running. This has the effect of topping up the heat of the small volume of DHW stored in the HEX.

But if a new DHW HEX with a smaller water capacity is fitted the by-pass flow could cause the now smaller volume of DHW to "overheat". This could possibly result in scale being deposited in the DHW side of the HEX and in scalding temperature water being briefly delivered to taps.

However the scaling effect is unlikely to be a problem in the short term and the overheated DHW may not be overheated by the time it reaches the tap and has run through some cold pipes. Note I say "could" and "may" because I really don't know to what degree any of these things might happen. That's why you have to make your own judgement.

There's another modification that's sometimes necessary when fitting the new HEX. Some models have a link on one of the PCBs that has to be cut. I have no idea why this is required, so best to ring Vaillant technical about that (and post what they say, please), unless someone else here knows.

 

[Agile]

Given the choice I would never want an uncontrolled heating flow to the plate HE.

If the taps are fully off then the scale deposition might be smaller but never a good idea.

I saw a plate which had become almost completely blocked by an iron/calcium/magnesium compound. That was the first time I had encountered this problem and it took a little research to work out what had happened.

The hot tap had been dripping for several months and the user kept the boiler on max CH ( 85° C ) as her rads were a little undersized.

I concluded that the compound could form as a result of cast iron supply pipes and that it was deposited more easily than normal lime scale which I never normally ever see in London on a boiler with proper temperature control.

Tony

 

[NotTheRedWire!]

Thanks guys for all the info.

I have contacted ezypart.co.uk and asked them about the missing disk in the kit and also to confirm whether this is indeed a genuine kit. They said that they had a 'deal' with Vaillant to supply these kits and make them up themselves. I'm guessing that is a long winded way of saying no its not genuine. Also they didn't know what I was talking about when I mentioned the missing diverter valve disc. They said they have supplied loads of these kits since 2003 and have never been asked about the diverter disc.

I'm more confused than ever now, i've half a mind to just send it back as I do not want to carry out the upgrade only to introduce new problems down the line. If I could locate this disc separately it might be an option but I am still a little concerned.

 

[NotTheRedWire!]

Just a quick update for anyone who is interested.

I have spoken to Vaillent Tech team themselves over this issue and they have informed me that the Diverter Valve mod and the PCB mod are required on the hybrid model only.

The said you can identify this by looking at the temperature dial spindle. A hybrid model will have a plastic temperature dial spindle, whereas the non-hybrid will have a brass spindle. If your boiler is a hybrid model, you also need to cut the W18 link on the PCB.

I have not looked yet to see which one I have but fingers crossed it is the Non-Hybrid.

 

[namsag]

As chrishutt says you will prob find that very few peple change the plate in the divertor.. This heat ex modification has been out close on 15 years now. And in my area we done a good few hundred on contract and not a single one got the plate changed and none at all suffered any ill effects. You will get some come on and be holier than thou and say this is rough etc. But for all the extra work and hassle its up to you.

 

[Dan Robinson]

NTRW (nice handle by the way) I hope you have the non-hybrid boiler, 'cos muggins 'ere had to do it the hard way .

 

[theartfulbodger]

I know this is an old thread ...but.....I have the Vaillant instruction in front of me... it says the diverter valve/ W18 mod is for hard water areas only.