worcester heatslave no heating or hot water

6 Jan 2011
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United Kingdom
Hi all,

This morning my Worcester heatslave 15/19 has decided not to work. The boiler started as normal but I have no hot water or heating. The central heating pump within the boiler is running and the pipework either side of the pump is hot but radiators are cold, the pressure gauge is showing pressure. When the hot tap is turned on I can hear a relay click but the boiler doesn't fire and I don't get hot water. I've turned the thermostats on the boiler up but this makes no difference. The boiler doesn't lockout and the heating pump continues to run.

Any ideas what the cause might be?

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A little bit more info. I operated the lever on the three way valve and the water went from cold to not-so-cold and the heating warmed slightly. I've read about the three way valve and flow valves but non the wiser.

Some more info:

Got home tonight and after boiler being switched off all day and notice pressure had dropped very low. Topped it off to 1BAR and having read about tripping off on here, pressed the trip button under the control panel.

Also checked the pressure in the expansion vessel, this showed 2psi so brought the pressure upto 12psi and fired the boiler.

Boiler fired, heated rads and hot water but noticed the pressure gauge creeping up to 2BAR. The pressure vessel is cold so is the pipe running to it.

Any thoughts? anyone? (please)

Not meaning to patronise you mate but the air pressure in the expansion vessel can only be accurately checked and reset when the system is depressurised.
If you can do this, pump the EV up to around 10 psi. If there is any water present when you press the air valve, the EV is goosed.
Pressurise the system via the filling loop to around 1 bar - it should rise to around 1.5 bar with the CH on.
Any sign of leaks from the PRV outside, or the AAV on the top of the boiler?
John :)
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Hi and thanks for the reply,

I checked the pressures when the boiler was cold and the gauge showing very low, filled the system via the loop then pumped up the vessel but like you say, incorrect order although no water came out of the valve on the vessel. The PRV is dry so is the AAV although it looks like the AAV has seen some action in the past but no recent signs.

At the moment it's running but the pressure is sitting on 2BAR. Is there a way to test the PRV?

The drama contiunes:

Just noticed leaking water from the bottom of the expansion vessel. I think I'll order a new one and a pipe to go with it.
PRV's are set to lift at 3 bar - but don't encourage it as they often don't like sealing again.
It looks like you've found the fault anyway - the EV is leaking around its folded seam. It could be worth getting hold of an AAV at the same time.....
Be lucky!
John :)
Just a final update on this job.

Fitted the new expansion vessel today from local supplier.

All working now. Thanks for the replies chaps.


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