Vaillant-lukewarm water

[grifftheriff]

I have a Vaillant VCW GB 242 EH (could be a 282 EH-does anyone know how to tell the difference?),running on LPG,which gives only lukewarm water from hot tap.

The central heating works fine and the boiler ignites no problem when hot tap is turned on,but the water runs cold for ages especially upstairs,and the gets only lukewarm at best.

If you reduce the flow of the tap it gets a little warmer,but if you reduce it too much the flames go out and it runs cold again.

I am pretty handy at most things and in the past have fitted a new divertor and microswitch so unless it involves some major surgery,I could manage if I had a little help on where to look for the problem.

Cheers

 

[Boilerman2]

Has your boiler got the original Cylindrical Hot Water Heat Exchanger fitted? or has it been modified to the more modern Plate Heat Exchanger?
if you have the former I suspect it is scaled up

Vaillant to a conversion kit to upgrade the old type to new, but it is a REAL PIG to fit and extremely invasive and given the age of this boiler it may be time to replace it with a nice Ecotec LPG model (they are a million times better than your old VCW

 

[grifftheriff]

Thanks Boilerman2 - what kind of cost am I looking at for the Ecotec?

I suspect you`re right about it being the old heat exchange! Is it much of a job to de-scale it? Could I do it myself or is it something that would be done under a service as it`s about due for one!

 

[kevplumb]

Has your boiler got the original Cylindrical Hot Water Heat Exchanger fitted?

that was the sine 18

the vcw had/has a flat black plastic one

i would check the operation of the servo valve and the diverter valve

before you go buying a new boiler

 

[Beerlover]

Look on the front of the contrlol box, can you see a green light glowing? If not it is one of the pcbs gone. (electonics board IIRC). If yes, can you hear the diapragm pump running (sounds like a fish tank air pump), if not then your boiler is not going to high gas. Check pin 7 for 20v dc to chassis earth, if not transformer gone. If yes then diapragm pump likely gone.

 

[The831Bunny]

My monies on split diaphragm pump elbow and/or blocked injectors. Gas Safe engineer required in each case.

What you say Bunnyman?

 

[Bunnyman]

Yes 831 split elbows on diaphragm pump stretch the tube to fit lol! Ur van but u were only one sad enough to have a camera!

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[grifftheriff]

Okay-took diaphragm pump out as per Vaillant handbook-you were absolutely spot on lads with your diagnosis.Both elbows were split.

Took them off,fitted the tubes back on-started re assembling and realised the two tubes that go to the left and right,at the back of the casing,have both come off while I was working on the pump.

As the handbook never mentioned these,I haven`t marked them and don`t know which one goes to whick nozzle!

I have two tubes-one goes up towards the furnace area and the other goes to the central area-looking from the front does anyone know which one goes to the left and which to the right?

 

[grifftheriff]

Right........job done!!

Took out the diaphragm pump,as I said in last post,took off the two plastic elbows which were both cracked and pushed the pipes straight on to the posts.

If you attempt this job make sure you mark the two pipes both at the back of the diaphragm pump housing and inside,before you remove everything.Both the outside pipes came off on my job and although I`d marked the inside,I hadn`t done these and was confused as to which pipe went where.

I also had to completely unwire the boiler,taking out the wires from the timer to the main terminals as there was not enough slack on the cable to allow the housing to be pulled forward.Make sure once again that you make a note of which cable goes to which terminal.

After figuring out the pipe situation,I put it all back together,re wired and fired it up............hey presto-hot water again after months of lukewarm drizzle!!!

I`d like to thank everyone on this forum for advice,especially the members who took the time to answer my queries.
Cheers everyone.