Calling all heating engineers

[MadAdey]

I wonder if you could give me some advice please. I have a GLOWWORM ultracom CXi boiler. When you run the hot water the boiler switches on to heat the water but it will come out really hot then go cold, then heat up again and go cold all the time you have the hot water tap turned on. I did have a leak from the 3 way valve which I fixed this afternoon.

The central heating system is working fine and is nice and toasty warm.

Anyone be good enough to give me some advice on what the problem is please.

 

[Brookesy]

Sounds like your secondary heat exchange( hot water ) is blocked or scaled up, will probably need changing

 

[6inchcup]

does sound like a heat exchanger problem if it is a newish boiler and in good condition go for the repair but to be honest for a little bit extra you could have a new boiler fitted that has a 5 year warranty,the cost of a new heat exchanger fitted is around the £300 mark.