Central Heating will not switch off

[ASJ]

A few month's ago I had to replace a 2-way motorised valve for the central heating system.

Recently I found that when the central heating is switched off at the timer, the pump keeps going. I checked the boiler and that too keeps going.

I have to turn the power off completely before it will stop.

Although the motorised valve is moving backwards and forwards when the CH is switched on and off, could it possibly be the cause of my problem?

 

[gas4you]

The motorised valve has a microswitch in it that is activated when the motor opens and reaches the full open position. It could well be that this has stuck in the on position. If you are comfortable with live electrics check for 230V on the orange wire comning from it when heating is supposed to be off. If live then it is the microswitch stuck.

 

[ASJ]

Dave,

Your a star! You've made my day. The orange wire was live, so it must be the microswitch as you say. Many thanks for your help!!

I think that on the replacement valve, 4043h, I can just replace the head without having to drain the system down again, so it shouldn't be too much of a pain.

Alan.

 

[gas4you]

As others on here have reminded me in the past, check there is a metal raised 'spot' on the top of valve head. If there isn't then you will have to replace the entire valve

 

[ASJ]

Well, I replaced the motorised valve that I thought was faulty ... live orange wire ... but still the same problem.

Know what the problem was? .... the OTHER motorised valve!! It looks as though the orange wire contact for BOTH valves are live even if the microswitch in only ONE is not switching off properly, even though they are on opposite sides of the termainal box.

unfortunatley, the other valve did not have a replaceable head!


Alan

 

[gas4you]

Both orange wires go to a common terminal in the wiring centre. You need to remove orange wire and test on its own