Central heating with a mind of its own

[MalcOfYorkshire]

Can someone advise me, please? My system is getting on a bit and has started behaving erratically. I have an Ideal Elan 20 boiler, conventional cylinder, roomstat in the hallway, and a fairly new programmer. The diverter valve is in the airing cupboard above the pump and has a lever sticking out of the bottom which I can move from side to side. I know what the DV does but I can't see any evidence that it's switching correctly. Should this lever move by itself? I'd describe myself as a competent diy-er but as far as CH is concerned the only tool I possess is a bleed key. Safer that way..
The problem is that the heating has been coming on even though the programmer says it should be off. Today I set the roomstat down to about 13 C yet the radiators are warm - the HW is set to be on all day, but I wasn't using any water. Yesterday the only way we could stop being baked alive was to turn the CH off on the programmer. Turning the roomstat down didn't turn the boiler off. I have a BG contract for my sins but before I call them in I'd like to be little more informed just in case it behaves itself when the engineer's here.
Thanks is advance!

 

[twgas]

should think the diverter is letting by, BG should sort this under contract (presuming you've got system care - used to be known as 3* (still is by most of us). they may well advise you need a power flush as valves are affected by dirty water.

 

[MalcOfYorkshire]

Thanks for that, Mick. Now - today, the CH went off at 830 and by 10 it was getting a bit chilly. So I pressed the advance on the programmer and it came back on. Went off again about 11 and I couldn't get it to come back on - moved the stat up a bit (heard it click) but zilch from the boiler. Left it and froze..well, got a bit parky shall we say. The timer is set to switch it back on at 530pm so I thought I'd wait and see if it came back on then. Remember I'd advanced it so the programmer light was on. It came back on at 4pm all by itself. I really want to suspect the roomstat as well as the DV. Any more thoughts? And thanks in advance.

 

[MalcOfYorkshire]

Thanks again Mick. It was the valve - it wasn't closing the switch, or if it did the switch was then sticking shut.