Boiler problem

[hayleyw]

Hi all

I have a worcester 28 cdi boiler and the mixer is a thermostatic Triton.

My problem is the boiler starts up but after a while the water goes warm for a bit then cold and then the boiler kicks in again. It does the same for the bath too.

Im on my 4th shower mixer now and I have still got hot and cold water so it really cant be the mixer?

My plumber does say that the pressure drops when I turn the shower on.

Any ideas pls

 

[heatserve]

Usually the water to water heat exchanger (WB term for plate heat exchanger), easy enough job to fix.

Budget for about £200 all in.