No Heating

[njrbris]

I have DHWC system with separate 2 port motorised valves for HW and Heating. The HW circuit works satisfactorily but, from time to time, the heating circuit will only work for a few minutes at a time and then shuts off. Is this a duff motorised valve?

 

[jackthom]

It could well be the valve for the heating circuit.

A common fault is the CH works OK only while the boiler is already ON to heat the water cylinder. When only CH is required a faulty valve can fail to ignite the boiler and the pump won't run either.

Does that seem to fit with what you are experiencing?

 

[njrbris]

Thanks Jackthom.

I have programmed the HW to start 5 minutes before the heating; sometimes the heating will then continue after the HW tank is satisfied. Today it shut off a few minutes later and then seems to come on for a few minutes every hour or so. Yesterday it worked OK.

 

[jackthom]

If the boiler is staying lit even after the hot water is satisfied it's not quite so straightforward although the valve could be working intermittently.

When the CH stops working is the pump still running or does it also stop?

I should also ask if the radiators all get nice and hot when the CH is behaving itself.

 

[njrbris]

If the boiler is staying lit even after the hot water is satisfied it's not quite so straightforward although the valve could be working intermittently.

When the CH stops working is the pump still running or does it also stop?

I should also ask if the radiators all get nice and hot when the CH is behaving itself.

The pump stops when the CH stops working. The radiators do get hot when the CH is behaving itself

 

[jackthom]

Are you competent with mains electrical wiring and do you have a multimeter or mains tester screwdriver? To be certain of the cause of the problem you would have to disconnect a valve wire from the controls connecting strip and make a couple of measurements.

 

[njrbris]

Are you competent with mains electrical wiring and do you have a multimeter or mains tester screwdriver? To be certain of the cause of the problem you would have to disconnect a valve wire from the controls connecting strip and make a couple of measurements.

I think its time to send for my friendly electrician but many thanks for your guidance. Perhaps I should come back to you when the problem is solved.

 

[jackthom]

Very wise if you're not happy with 240V.

You can always pick up this topic again if that doesn't get it all sorted out.