Hey guys - I have a Potterton 80e Combi in the loft - it was here when we moved in so I guess it's about 8 years old. It has always been a bit slow to deliver hot water to the tap and the water flow takes a long time to build up. But yesterday it stopped delivering hot water altogether - I turn on the hot tap and hear the pump working but it never gets hot and the water flow remains weak - radiators don't heat up either, but again I can hear the pump. I have had a look on the unit and can see LOCK-OUT lit. I plan to call out someone and want to be prepared to sound knowledgable when / if he starts giving me ridiculous quotes. What do you think?