I've a problem with my vokera boiler whereby it fires up ok when central heating is requested but then the heat doesn't come through to the radiators. The temperature reading on the boiler then goes up until it's about 5 degrees over what the boiler is set to then the green light goes off and it sort of just purrs away but doesn't provide heat. We've had a man out to it who reckons that the heat exchange has gone due to excessive sludge/slime build up and what's required is a power flush costing £400+. Does this seem a reasonable assessment? A build up of sludge and slime seems unlikely to me seeing as the boiler's only 3 years old.

grunos, December 2009

It could be the heating thermostat is shot. If it fires up and goes up over 70 it may then be cutting out on the emergency cut out thermocouple which is attached to the hot output pipework. If it works ok on the hot water but not on the central heating, test and/or then replace the heating thermostat (partmaster.co.uk). Instructions for easy testing of individual thermostat are covered elsewhere on the net.Easy to do.

John the tradesman beater, January 2010

what model of vokera is it?

Ian, December 2009