Heating motorised valve will not shut off!

[mcsawyer]

Help please!

My (gas) central heating system has a twin port motorised valve. When the room stat calls for heat, the C/H motorised valve opens and the boiler lights.

However, when the room stat calls to stop heat, the C/H motorised valve stays open & the boiler keeps burning.

The C/H motorised valve does'nt seem to be sticking, Because if I switch off all heating and hot water from the control box the C/H motorised valve closes immediatly.

The hot water seems not to be affected by these problems.

This is a new one for me. Please, any ideas anyone? [/i][/b]

 

[seco services]

when you say the room stat stops calling for heat check to see if the brown wire on the valve is still receiving power.

sounds like it's still getting a call for heat as it closes when the mains power is isolated.

what happens when you turn the heatring off at programmer ?

 

[nickso]

is this with heating on its own or with HW on too?

 

[mcsawyer]

when you say the room stat stops calling for heat check to see if the brown wire on the valve is still receiving power.

sounds like it's still getting a call for heat as it closes when the mains power is isolated.

what happens when you turn the heatring off at programmer ?

Hi Seco, thanks for your reply. Trying to conduct your checks I find that the system is now working perfectly. Typical. I have the M/V stripped and am trying to duplicate the fault through today. As of this moment the orange wire in the M/V is dead as the room stat has stopped calling for heat, just so. So far am on about the 8th cycle.
As for your Para. 2, I agree.
Regarding Para 3;- when the fault was evident, turning just the heating off at the programmer did not affect the M/V. It was still open, and the boiler still burning. The only way to turn the heating off was to turn both heating AND hot water off. The M/V would then immediatrly close, and boiler stop burning.
Do you think that this might be a programmer issue? It is a normally very reliable ( ie., never failed ) Potterton EP 2000, retro installed some 5 years ago.

 

[seco services]

The only way to turn the heating off was to turn both heating AND hot water off. The M/V would then immediatrly close, and boiler stop burning.
Do you think that this might be a programmer issue? It is a normally very reliable ( ie., never failed ) Potterton EP 2000, retro installed some 5 years ago.

i would check to see if the wall stat is still getting 230v when you say you turned heating off but the valve was still open etc.
but then if the programmer was still sending power the wall stat should cut the power to valve when stat turned down.

what make/model valve is it ?

 

[mcsawyer]

is this with heating on its own or with HW on too?


Hi Nickso. Thanks for your reply.
The problem manifested itself with the water on as well. The only way to turn the heating off was to turn the lot off at the programmer.
Unfortunately the programmer ( a Potterton EP 2000 ) does not permit heating on without the hot water on also.
Further testing is however being frustrated by the fact that the system is now working perfectly! Not sure for how long though.
Do you think that this might be a programmer issue instead?
Observing the M/V with the aluminiam casing off, the valve does seem to be working correctly, with the orange wire live when it should be.

 

[seco services]

i take it gravity hw pumped heating then ?

 

[mcsawyer]

i take it gravity hw pumped heating then ?

That's right. And so far the damb thing's behaving itself. Just a glitch???

 

[mcsawyer]

i take it gravity hw pumped heating then ?

That's right. And so far the damb thing's behaving itself. Just a glitch???

The heating M/V is a Honeywell 2 port F6 - 9306