potterton ep2000,,,hw only works when ch is on?

I have this problem on a ravenheat boiler - Just changed the diaghram on the diverter valve - and both ch and dhw censors . no joy . Ranenheat told me over phone its probably the heat exchanger - at 200.00 a pop ill replace the whole boiler ( 439.00 for the condensing equivalent from toolstation ) Wish I had invested in an antiscale device !

Jon Hinch
January 2009

Found this page searching to an answer to the exact same problem that I have! I hope Bri has fixed his by now. In my case I've isolated the fault to the diverter valve behind the hot water cylinder. Seems its sticky and a bit of pressure on the actuating arm completes the elec circuit for the boiler to start up.

Can I just replace the diverter valve with a new one? Is that a diy job? Would I need to drain the system?

Richard M
September 2007

either the diverter valve is sticking or the diapragm is split id go with changing the diapragm first ok

tony joint south wales
October 2006