Hello
Is it a difficult job to replace this. Had 2 gas engineers look at it (including Vaillant themselves) who said boiler needs replacing. Seems to cost around ~£80 online so why condemn boiler?

Thanks for any advice - not keen on replacing whole boiler as moving house soon.

Tony, January 2008

Replacing the domestic heat exchanger is absolutely simple and quick, not a rocket science, its a nut & bolt job, ensuring all o rings are replaced with new, and then just bleeding the system.

Mike, October 2008

Just want to say thanks for your responses. Bought the new type plate exchanger from a local plumber's merchant (£80) and paid a decent corgi registered plumber £60 to fit it - (took about 2-3 hours).

Prior to this two plumbers (including Vaillant themselves!) called out and condemned the boiler claiming the only solution is a complete new system.

So cheers

Tony, February 2008

I had the same problem about 6 years ago, the original hex was made from noryl, the replacement kit is st.st. with pcb & other parts in a kit with full instructions. Mine was fitted professionally + service & bleed in half a day. Its been fine ever since. The kit was over a hundred quid then.

Ed, February 2008

Further to my last answer - I've since heard it mentioned elsewhere that changing the HEx also requires some work converting the diverter valve and the pcb, and that this is a lot more involved - maybe why mine is still giving problems. So check this out before purchasing the exchanger kit.

Rob, February 2008

It's not a very difficult job. Isolate the CH system using the flow & return cocks, drain down the boiler, undo 4 compression nuts and unbolt the heat sensor. Remove the four old pipes that connect the boiler to the HE, then fit the new pipes and exchanger. Refit the sensor (which was a little bit fiddly in my case because the screw holes on the pipe lug were not threaded) and refill the boiler.

I paid £90 including vat and p&p so if you can get it for 80 good luck to you. As long as you have some plumbing/diy experience and some common sense then it's not complicated, but will probably take you a couple of hours from start to finish.

Having said all that, I've had further probs with the boiler (diverter valve, now something else I can't identify), so I'm beginning to think I should have just replaced the blasted thing!

Rob, February 2008

common fault on this boiler part is available as kit will take a good hour for someone qualified and knows what they are doing

bill, January 2008