I'm using a Potterton Neataheat 10-16 when I switch on the Central Heating the Boiler fires up as normal the Radiators get hot, but the water is cold ?
Tried turning on hot water only, the boiler fires up as normal, the flame is there, but the water is still cold?
It's been working well for years before this latest problem started?
Any ideas how to resolve this.

Fitz, February 2010

if you set the system to hot water only the boiler cant be running for long if the water remains cold, this could be because the pump has failed or the whole system needs venting, possibly you have sludge blocking the flow of water through the hot water cylinder, is your motorised valve opeen ing to allow boiler flow to the hot water?/

john, February 2010