UKC

I have a Worcester Heatslave 20/25 oil-fired boiler, of around 2003 vintage. It's providing hot water, but not central heating. The room thermostat is calling for heat (as am I), and it's clicking but it's not firing the boiler.

I'm at a loss as to what to try. I suspect the diverter valve, as it's played-up in the past (heating running without being requested by the room stat). I'm not sure where it's located, how to test it and whether it can be manually over-ridden to provide some heat.

There is sufficient pressure in the CH system.

Any suggestions gratefully received.

Thanks in advance.

In reply to Submit to Gravity: It may look like this http://wiki.diyfaq.org.uk/index.php?title=File:CH_motorised_valve_Honeywell...

if that's any help locating it. Sorry for stating the obvious but it will be somewhere after the hot water leaves the boiler where it splits, maybe under floor boards if you have checked the obvious places.

It might have a lever you can fiddle with.

It may be an electrical fault not the valve.

MrMarsbar is at work at present, I can ask him later for proper information!

In reply to marsbar: Cheers)

In reply to Submit to Gravity:

You could always follow government advice on central heating systems and put a jumper on. ;0)

In reply to teflonpete: I've just won a fiver...)))

In reply to ebygomm: No, it's all within the boiler.

In reply to Submit to Gravity:

Well, the jumper quip was inevitable. Hope it was only evens. ;0)

In reply to Submit to Gravity: Bump)

In reply to Submit to Gravity:

First principles - check whether the boiler is actually receiving the call for heat! Room stat may be clicking but electrical contacts burnt out, a loose or broken wire might be preventing the signal being sent.

If you're comfortable with a multimeter you can check whether the voltage on the switched live into the boiler.

It could be a sticking diverter valve, if so you may be able to unstick the microswitch.

It's pretty easy to recognise, it's an aluminium cased rectangle above the pump.

It may also be a faulty flow switch keeping the DHW demand on even without a tap being on. That's a bit harder to recognise and can only really be diagnosed with a multimeter...

In reply to Cthulhu:

And therein lies a problem...

Thanks for the advice. There is a white plastic lever on the side of what I think might be the diverter valve, which is in the upper position and I can't shift it. Could that be a problem?

In reply to Submit to Gravity:

I've PMed you my email address. If you can send a picture I'll confirm and talk you through what you can do...

In reply to Submit to Gravity:
If it were just the diverter valve the boiler would still fire up when the thermostat kicks in it just wouldn't heat the radiators.
As said above, you need a multimeter to test continuity across the switched contacts on the thermostat.