Central heating didn’t come on

[MyNameIsUrl]

Had another visit today and it’s clearly a faulty pump.

The boiler does fire when the heating is switched on but goes off quickly (presumably flow sensor as Mike4 said) and what alerted me to a pump problem was the pump became hot although the pipes didn’t. A screwdriver on the end of the shaft got it spinning, with a horrible rattling sound which fluctuated from very loud to not-quite-so-loud.

A replacement pump (Grundfos Super Selectric UPS 15-60) looks relatively easy – for a plumber – but should we get any other work done at the same time? Does sludge cause the pump to fail? Or conversely does a failed pump (it may have been like this some time) cause other issues? The system is from 1995, is not a combi, and has pipes which look to me like 10mm OD.

[Mike4]

Servodude:
“Ah the Worcester uncertainty principle in all its glory! (With apologies to Heisenberg) “

Well I suppose a cat might have got stuck in it somewhere but you’d need to open the case up to see whether it was still alive.

Well firstly, surely it isn't a case of the cat being 'still alive'. Mr S's hypothetical cat is both alive and dead at the same time when concealed inside the boiler, but settles on one state or the other when observed, AIUI.

Secondly, the older Woosters (preferred spelling amongst plummers) don't have a flow switch anyway, hence my question about which model Wooster it is.....

[Steveam]

“The system is from 1995 …” 26 years old! I’d just replace it. Modern boilers are more efficient and extremely reliable.

Best wishes,

Steve

[bungeejumper]

A replacement pump (Grundfos Super Selectric UPS 15-60) looks relatively easy – for a plumber – but should we get any other work done at the same time?

I replaced my Grundfos a couple of years ago, and it was totally peasy. All right, it does help if the gate valves on either side of the pump are in working order. (Mine were.) But since you mention that particular model, you can buy just the head unit for £119 and save yourself the heavy-duty plumbing work. https://www.plumbparts.co.uk/product/gr ... eter-head/

The shaft itself will pull away from the body with a bit of gentle persuasion, to release the turbine vane behind it, which might well be in need of uncrudding. (Mine was.) Grit and grot have a tendency to do that. But all in all, it's not a major undertaking.

The system is from 1995, is not a combi, and has pipes which look to me like 10mm OD.

AKA microbore. Very fashionable once, but it does put a lot of stress on a pump. My missus's old system had two pumps in series!

[Edit] Should have added. A popular cheapo remedy is to thump the pump with a lump of wood. In the hope that it'll dislodge or break up whatever bit of sediment is causing your noise. I couldn't possibly comment.

BJ

[servodude]

My missus's old system had two pumps in series!

Humblebrag?

[MyNameIsUrl]

I replaced my Grundfos a couple of years ago, and it was totally peasy. All right, it does help if the gate valves on either side of the pump are in working order. (Mine were.) But since you mention that particular model, you can buy just the head unit for £119 and save yourself the heavy-duty plumbing work. https://www.plumbparts.co.uk/product/gr ... eter-head/

The shaft itself will pull away from the body with a bit of gentle persuasion, to release the turbine vane behind it, which might well be in need of uncrudding. (Mine was.) Grit and grot have a tendency to do that. But all in all, it's not a major undertaking.

Thanks, I may have a go at this - I'm nervous about leaks but this method presumably involves splitting the body at a flat gasket, rather than the two flanges which would be required if the whole pump is replaced? Is the repair repair as good as full replacement, ie is the part which isn't replaced just a casting with no moving parts or bearings?

[bungeejumper]

Thanks, I may have a go at this - I'm nervous about leaks but this method presumably involves splitting the body at a flat gasket, rather than the two flanges which would be required if the whole pump is replaced? Is the repair repair as good as full replacement, ie is the part which isn't replaced just a casting with no moving parts or bearings?

Certainly was just a plain casting on mine, which was the more modern Alpha 2 variant, although I reckon it was just the same old pump with an electronics box on the front. There are plenty of video guides on Youtube, though.

Would probably be a good idea to flush your system while you're at it, though. Sentinel X400 is usually my weapon of choice. Others may suggest that you install a Magnaclean, but heck, you'll probably get one of those on the evil day when you change your boiler.

BJ

[88V8]

“The system is from 1995 …” 26 years old! I’d just replace it. Modern boilers are more efficient and extremely reliable.

I wouldn't
Modern boilers are overcomplex and very unlikely to last 26 years.

I would agree the system should have a flush, and ensure afterwards that there is a correct concentration of water treatment in there. To me, that is the absolute key to a reliable system.
The pump in the gfch I installed in 1982 was still going strong when we sold the house in 2011, despite it being a fully pumped system.
Admittedly, not the dreaded microbore.

V8