engineer been ,replaced diaphragm and sensor ,but water is only tepid ,but hot when central heating on ..he says it must be heat exchanger , I am with homeserve ,but he says I will probably have to pay for it myself ..how much is this part ..i am covered upto £250 per year ,he has been twice ...will the £250 have been spent by now?

g.fray, March 2008

check when c/heating is turned off,turn on hot water & check if c/htg flow pipe is getting hot.If this is what is happening then the diverter valve(located on bottom left of boiler) requires overhaul kit. What is happening is when in hot water mode,diverter valve is not putting all the hot water produced in the main heat exchanger to the domestic hot water plate heat exchanger but is losing the heat to the c/heating system

rossrob, March 2008

Does the boiler go to full flame with hot water only selected when you turn on a tap?. If you only get hot water when the CH is on the DHW microswitch may be broken (quite common).
Or...With hot water only selected and the hot tap running (and burner on, assuming the DHW microswitch works) do the radiators heat up?. If so suspect the three port valve is due its regular service. The parts come with the excel/eclipse service kit.

c, March 2008

HE IS RIGHT THE DIY WAY WOULD BE TO EMPTY THE SYSTEM AND ADD A DESLUDGER AND LEAVE IN FOR ABOUT A WEEK THEN EMPTY AND TOP UP AT LEAST HALF A DOZEN TIMES OVER THE NEXT COUPLE OF DAYS IT WILL HELP BUT IT WILL NOT BE PERFECT UNLESS IT IS POWER FLUSHED BG CHARGE £400 APP

MICK, March 2008