Vaillant VCW 242 EH DHW HE

[paddy69]

Hi!
Can the people in the know here help me out?
I have noticed recently that the DHW out of my old (trusty) Vaillant VCW 242 EH combi compact boiler is not coming out as hot as it did. I have just replaced the diaphragm pump as I got one really cheap (the old one had the split plastic elbows). I haven't measured any temperatures but just on feel, the water into the DHW heat exchanger (old black cannister type) is absolutely scorching, and the water out not! Diverter valve is fine as NO hot water is getting into the central heating side of the system. And the flow rates have been all adjusted down so there isn't too much water flowing through!
So, aware that fiddling with the old heat exchanger will probably cause it to leak, I am thinking of getting one of the newer ones. My question is, do I need to get a kit with different pipes????
I have seen advertised just the heat exchanger and also heat exchanger with pipe set. Do I have to have the pipe set to convert from the old black plastic cannister type???
Many thanks!
Phil

 

[Agile]

I would never work on a boiler until I had taken readings of all the operational parameters to assertain if the problem was with the HE or some other aspect.

Your boiler is old and better replaced.

You can replace the plastic heat exchanger with the kit with pipes.

Many cheap ones are NOT genuine Vaillant ones and usually come with no instructions or washers.

Even boiler engineers do not relish that job and allow up to two hours for the job.

Tony

 

[paddy69]

Thanks Tony!
Would I clearly be able to pinpoint the DHW heat exchanger by measuring temps of heating water in and out and DHW in and out or is there a lot more to it?? Do I need to do an accurate measure of DHW flow rate??
I am loathed to change what has been a very reliable boiler, that is working fine apart from the DHW not being just as hot as I would like. I could spend £200 but I don't have £2000 to spend just at the moment!
Cheers!
Phil

 

[Andygasman2010]

Don't change this boiler unless you have to, they are very good and very reliable. It sounds like your plate heat exchanger is blocked which isn't even the boilers fault, it's some external factor.

I can't think of any reliable tests for you to do that don't involve removing the combustion cover or doing gas related checks.