Heating staying on continuously - programmer not working

[bolti25]

We have a Horstmann Channel Plus H27XL programmer with separate time controls for the heating and hot water, as well as a room thermostat. These controls have always worked well until the last couple of days when the heating and hot water are staying on continuously, regardless of whether the programmer is set to OFF or if the times are set to be off or if the house has reached the temperature set on the thermostat - everything just stays on unless you turn the boiler itself off.

I have reset the programmer but it has made no difference. Any suggestions as to anything else we can try or as to what the problem is likely to be?

Thanks!

 

[buck51]

Zone valve micro switch stuck in the on position!

 

[bolti25]

Thanks for that. Is that something easy to sort out?!

 

[Blagard]

Thanks for that. Is that something easy to sort out?!

Easy if you get a replacement microswitch and are handy with a soldering iron.

For most, changing the head would be easier as it is just a case of fitting the new head and replacing the connections like for like in the wiring centre. Certainly the microswitch is much cheaper if you can manage it.

 

[ianmcd]

for an experienced engineer yes, but your system will have to be drained unless the valves you have use removeable actuators