Central Heating won't turn off......

[Timbracey]

We have a Drayton LP522 dual channel programmer that controls Hot water and Central Heating. This has worked fine for many years, but in the last week it does not turn off the pump, boiler etc, when the "off" time is reached. So at 22:00 when CH is meant to stop, it goes on thro' the night. OK when it was very cold, but not ideal......! The programmer does click off at the right time, as the red light indicating that the CH, or Hot Water is off, goes off, but everything still carries on! Need to turn off power to the programmer, pump and the 2 valves in the airing cupboard, to stop system. And then get up early to turn power switch on again at 06:00....... Anyone got any ideas? Faulty boiler component that is not recieving the signal from the progammer?

 

[Terrywookfit]

Probably a faulty m/v.

 

[Timbracey]

Many thks. We have 2 valves, both Honeywell V4043H. Which seem to be the sort that are normally closed. They have switches that have "auto" selected, rather than the "open" option. One valve is on a pipe that goes into the hot water cylinder half way up, the other one is on a pipe that the splits into 2 - one to pump and other to the base of the cylinder. Any idea which one is faultly? The one that seems to feed pump and base of cylinder? But then the pump still keeps going after Programmer switches off. Its all confusing to me......I would have thought that the Programmer would be the master and ensure everything goes off when required......
Grateful for any more advice before we call an engineer.

 

[griggs]

Select hot water only, heating off, when hot water switches off do you hear valve motor across, does boiler switch off? If so, try same with heating valve, you should then be able to identify which valve is faulty.

You can also do the checks with a multimeter.