Thanks for the replies guys, both points taken. I do believe a faulty batch of switches is possible and after a re-think we have gone for a new boiler, could have ended up a money pit I guess. But OMG the cost of a boiler replacement! Picked out a Remeha Advanta 28c, its so much smaller and oh-so efficient, £2200 fitted with 3 new TRV's and a Seimens wireless thermostat. Straight forward installation on a kitchen wall so at about £1400 labour, thats two men for one days work, I was astounded. But hey! that seems to be the going rate, probably a bit more cos we picked a franchised outfit so theres middle men to pay, I realise that but, hopefully gives peace of mind if any probs later on. Thanks again.
Ken, July 2009