My FIL's heating is playing up.

If the heating is set to run all day it works perfectly first thing in the morning until it reaches temp and then for the rest of the day the boiler keeps firing up and then shutting down and so it goes.

However if he turns the heating off and then in the afternoon (after some hours have passed) he turns the heating back on it works correctly again.

Any ideas??

It's an ideal boilers concord companion H45/55.

Cheers

Ken

I realise that it should cycle on and off with the thermostat!!!!

It fires up and shuts down immediately.... Hope thats clearer now

Will not be a flame supervision device because that will shut the gas valve off and consequently boiler will be out and not back on without a manual reset, with intermittant problems it can be a b****** but if it was me I would take a good look at the pump it may well run fine at first but could be sticking later and thats makes the boiler cycle on temp cutoffs. Definatly sounds circulatory to me. Regards Jimbo

i don't know if this is relevent to your case Chaddy, but i have a Potterton Suprema, and shortly after it was installed, it would try to fire and just lock out, or stop trying to fire,  then sometimes it would just carry on as normal.... if you turned it off for more than an hour, (via the mains!) it would be as happy as larry for about 4 hours or so,

it turned out to be a faulty mother board, my gas man got me a new one. swapped it out, and had no troubles since, as we went down all the usual route, thermocouple, sensors, roomstats etc etc, he pulled the board, and there was this small area of over heating around a component..
the rest is history as they say, may be worth a look, as my GM stated a while ago, most boilers will be perfect, if it was not for the unriliability of the circuit/motherboards!!!!

and that is all he does now on a German brand of boiler, !!!!!

[quote author=Chaddy  link=1138745527/0#5 date=1138832000]Cheers guys. would there be a thermocouple fitted and if so could that be playing up?? [/quote]

Is the above in reply to Benson's suggestion about the pump?

The pump is controlled by the room stat and/or the stat on the hot water tank (both via the timer).