Worcester heatslave 20/25

[heatslave67]

Hi all. I have Worcester heatslave 20/25 around 10 years old, it stopped working yesterday. Seems to be burning and igniting ok, but heating and hot water not working.
When I took the from off and switched up the thermostat to fire the burner, it didnt come on.. But when I reset the overheat sensor it fired back into life first time, however the water pump became EXTREMELY warm, too warm to touch, in a matter of minutes.
Can any body help please? is it likely to be the waterpump? or could there be a different fault? and is the pump easy to chanbe by a layman?
Im freezing... your help would be very much appreciated..
Thanks, Richard

 

[slapper]

It sounds as tho you've got a water related problem, switch boiler off. There are rad key vents under top case of Boiler, these need venting.

Make sure you fill the system back up thru the filling loop to 1 bar and then try Boiler

 

[heatslave67]

It sounds as tho you've got a water related problem, switch boiler off. There are rad key vents under top case of Boiler, these need venting.

Make sure you fill the system back up thru the filling loop to 1 bar and then try Boiler

Thanks Slapper, I'll take the top off in the morning, can you tell me what the rad vents look like? do i open them till air/ water escapes?
thanks, much appreciated

 

[Burnerman]

Look for 3 square bleed nipples on the top of the exposed copper pipes, and check the plastic cap on the automatic vent too.....it looks like (and is) a car tyre valve cap.
Loosen each valve in turn, let the air hiss out and then repressurise!
John

 

[oilhead]

Did the pressure drop? If so and you have repressurised, then it may be air. However, if that is not the case, then it could be the pump. It is easier just to change the head by undoing the 4 allen screws. Also , if the boiler was installed with isolators on the flow and return, then isolate the boiler there and part drain the boiler. Using the pump valves will mean they will weep after and you will have to drain down to change them.

 

[heatslave67]

Hi guys, thanks for all the advice.
Took the top off and loosened the square release valves, as will as the bicycle tyre shaped one, and only got a very small hiss of air from one of them, the rest all vented water, repressurised to just over one bar and fired up again.
all the pipes that I expected to heat up heated up, but again the pump seemed to overheat after about 4 or 5 minutes, no heating or hot water, tho I could hear it 'switching' ok as I turned the hot water on and off.
Any body think it's the waterpump? or still a water issue?
all advice gratefully received
Thanks, Richard

 

[Boilerman2]

Sounds like the pump is shot! it might be worth removing the silver screw in the front of the pump and putting a smallish flat blade screwdriver in the hole to locate the end of the pump shaft, give it a turn you should feel if the shaft is seized or turning - it is unusual for a pump on a Heatslave to seize due to constant use so suspect pump will need replacing (tip) DO NOT attempt to close the pump isolation valves - they WILL leak!! it is possible if very careful to replace the pump head, without the need to close the pump valves you need to let the boiler cool down, then depressurise the system, and close off the auto air vent on top of the heatstore, place a container under the pump, and loosen the 4 allen screws( do not remove yet!!) wriggle the pump head forward, you will find about a pint of water will leak out before forming a vacuum allowing you to remove the screws and swap the pump head

 

[heatslave67]

Hi guys, first thing first, your advice has been invaluable!!
I fitted a new pump, well a previously used pump, from ebay.
de-pressurised, carefully fitted and wired the new pump, then re-pressurised.
Bled the air again from the 3 square nipples, and the bicycle valves, then re-pressurised again (the black indicator, now set at just over 1 bar)
ps there is also a red indicator, which is up about 1.5bar.

So reset the overheat switch, fired up the boiler, and after a few seconds of gurgling, whey-hey, within 15 minutes my radiators were all heated up

Now a few last questions (I hope...)
Just how warm should the water pump get? it's really, really hot.. maybe I've just never noticed before?
and..
The black water pressure gauge has creeped up to 1.6bar while it's in operation, is that normal? do I need to bleed those valves again?.
Thanks again guys, your advice is much appreciated.
Thanks, Ricky

 

[Burnerman]

Those pumps do get really hot - after all they are very close to the boiler hot bits, and receive the water immediately it has been heated......worry ye not!
If you think the pressure is rising a little too much, it could be that the expansion vessel (bonny big red container) needs repressurising with air.
The system needs to be depressurised for this, and the vessel pumped up with air (tyre valve on the top) to around 10 psi.
If you depress the valve core and find water, the EV is goosed.
John

 

[heatslave67]

Those pumps do get really hot - after all they are very close to the boiler hot bits, and receive the water immediately it has been heated......worry ye not!
If you think the pressure is rising a little too much, it could be that the expansion vessel (bonny big red container) needs repressurising with air.
The system needs to be depressurised for this, and the vessel pumped up with air (tyre valve on the top) to around 10 psi.
If you depress the valve core and find water, the EV is goosed.
John

Ahhh... I've done something wrong I think..
I actually depressed that valve and let all the air out! doh!
so I switch everything off, depressurise back down to zero, put some pressure back into the tank and repressureise it to 10psi?
wow thanks, im indebted burnerman, thanks

 

[Burnerman]

Yes, the EV on a sealed system allows for expansion of the hot water.....the red tank has a rubber diaphragm down the middle - air on one side, water the other.
No air in the EV means the boiler will discharge water to the outside for safety.
So - depressurise the system, and pump the EV up to 10 psi (keep allowing the system to depressurise - disconnect the flexible hose to the EV if you want - then repressurise the system via the filling loop.
Usually 1 bar is about right, which will rise to 1.3 bar when the system is running the C/H.
Enjoy!
John

 

[heatslave67]

Yes, the EV on a sealed system allows for expansion of the hot water.....the red tank has a rubber diaphragm down the middle - air on one side, water the other.
No air in the EV means the boiler will discharge water to the outside for safety.
So - depressurise the system, and pump the EV up to 10 psi (keep allowing the system to depressurise - disconnect the flexible hose to the EV if you want - then repressurise the system via the filling loop.
Usually 1 bar is about right, which will rise to 1.3 bar when the system is running the C/H.
Enjoy!
John

depressurised (again...) pumped the valve up to 10psi, bled and pressurised again to 1 bar, heating has been running on the thermostat for the last 2 hours, and the pressure only rose to 1.2
Thanks John, your a star!!

 

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Started own thread