Hot water but no central heating

[Donnaidh]

Hi folks, so I switched the heating on for the first time since spring and I'm getting nothing.

It's a worcester greenstar oil combi boiler. The hot water still heats as it has done all summer.

I've had a look at the diverter valve. The control unit was very stiff coming off (drayton box) and there were blue corrosion stains round it but the needle moves from A to B when changing between central heating/ water and the spindle on the valve moves freely by hand so it doesn't appear to be stuck.

Am I missing something stupid, or could the valve be stuck in one position but the spindle still moves?

I'd appreciate any advice please, thanks

 

[ericmark]

Don't know which type of motorised valve you have, but micro-switch failure with the three port can stop CH working but still allow DHW to work, as a quick temporary fix, try latching the manual lever to bleed position, this some times works, but even if it does only a temp fix as you will find the radiators heat up slightly in summer if switch not replaced.

Seems daft the V3 switch is coppers, but likely you will need to replace whole head or even valve.

 

[XrayDave]

Hi,

We had avery similar issue - albeit on a System Boiler not Combi.

Seems that during the long down-time (our CH system had not been used since March) there had been a build-up of gas in the pipes/radiators preventing the water from circulating properly.

We could get both hot water and heating to the basement and first floor, but not the second floor.

Maybe you have a similar issue?

Do any of your rads need bleeding and what is the COLD water pressure in the boiler (i.e. when the boiler has been off for a long while and the water in the system is cold)

We found that one radiator in particular has needed to be bled probably somewhere between 7 and 10 times in the last week and the water in the system topping up.

If you find that you DO need to top up the CH system, bear in mind that extra water added will dilute any inhibitor that there is in the system and that this may need 'topping up'.

It may be of interest to look at my thread on the problem we experienced - link here

Hope this helps,

Dave

 

[Donnaidh]

Thanks EricMark, this is the unit. Interesting you say that because I'd noticed a couple of weeks before that there was some heat coming off the radiators in the mornings when the heating was still switched off. It's not doing that now!

 

[Donnaidh]

Thanks Dave but I don't think it's the same problem as none of the radiators are getting any heat on any part of them. The water pressure had been low but has been repressurised.

Hi,

We had avery similar issue - albeit on a System Boiler not Combi.

Seems that during the long down-time (our CH system had not been used since March) there had been a build-up of gas in the pipes/radiators preventing the water from circulating properly.

We could get both hot water and heating to the basement and first floor, but not the second floor.

Maybe you have a similar issue?

Do any of your rads need bleeding and what is the COLD water pressure in the boiler (i.e. when the boiler has been off for a long while and the water in the system is cold)

We found that one radiator in particular has needed to be bled probably somewhere between 7 and 10 times in the last week and the water in the system topping up.

If you find that you DO need to top up the CH system, bear in mind that extra water added will dilute any inhibitor that there is in the system and that this may need 'topping up'.

It may be of interest to look at my thread on the problem we experienced - link here

Hope this helps,

Dave

 

[Exedon]

Chances are it is diverter valve common problem but to be certain
Competent oil engineer required.

 

[ericmark]

Chances are it is diverter valve common problem but to be certain
Competent oil engineer required.

Is there such a thing? I had problems and at 70 crawling into cupboards to fit motorised valves is not my thing, I found a guy to fit them for me, but it was up to me to wire, he freely admitted he did not understand how I had wired them. However he did fix the boiler and he did fit the valves which is what I wanted, as an electrical engineer I can draw up the wiring diagram, but at 70 years old fitting the motorised valves was a bit too much.

The Y plan is not the easiest to get ones head around, the main point is default is domestic hot water, the valve has no power to it and no outputs to get domestic hot water, it is only activated when central heating is required. Since it uses DC the RCD when using Y plan should be at least a type A, the type AC RCD should not be used with Y plan. But as said before latching moves the valve to mid position for bleeding, and can often be used to get it to work when the micro switches have stuck.