Vaillant combi compact VCW GB 240H

[Grimly Feendish]

Hello All. This is my first post. Just moved into a house with an ancient Vaillant boiler which is not working properly. There is loads of pressure at the taps but (after waiting for ages and ages and wasting gallons of water) I eventually get lukewarm water at best. The only way to heat it up is to turn the tap right down, but more often than not the burner will then go out and I'm stuffed! I had a heating engineer look at it. The DHW heat exchanger was leaking and with limescale all over the outside, so he said it was useless and needed replacing. This he did (at a cost of £204), curing the leak but the problem of rubbish DHW supply has not been improved at all. Funny thing is, when the CH is running, the DHW is fine. Some other bloke told me that I had to have my system power flushed, but the engineer who changed the HE said I didnt because the rads were fine. In fact, two of the rads upstairs (6 in total - v small system) dont get as hot as the others, so that's another problem.

I need to keep this boiler alive for another 2 years if poss as I cant afford a nefw one right now.

One more thing: I think my heating engineer told me that as part of the conversion kit for the HE (its a plate tyoe while the old one looked like 4 plastic cylinders stuck together) he did something to the diverter?

Could the time it takes to get heat at the tap be associated with the pipe run length? Seems unlikely to me because its a small house and although the pipes to the kitchen are under a concrete floor, I dont reckon the run can be any more than 10 feet.

Any thoughts on this would be most welcome.

Alistair

 

[Agile]

You can always feel the pipe under the boiler and you should see that turning on a hot water tap makes that pipe gret hot within a few secs.

Its difficult for me to comment with technical info like hot water flow rates etc.

Tony

 

[chrishutt]

Did your engineer check the operation of the diaphragm in the water section? Most likely fault that I can think of, although this boiler has a complicated operating sequence involving several valves with hydraulic connections. You need an engineer who knows these VCWs well.