Replacement CH pump.

[John]

The pump on my central heating system has failed - just after the boiler was serviced the boiler started to make 'cranking' noises as if it was too hot, so I turned the pump up to top speed (it has been on the middle setting for over 10 years) but a few days later there was no circulation (pipes going into and out of the pump were cool, no heat in downstairs rads) even though I could feel the pump vibrating.

It is an SMC Comet 2-130. I understand SMC don't make pumps anymore. Is it going to be a problem getting a replacement pump? There seem to be isolating valves above and below the pump, so presumably no need to drain the system (it's an ?indirect? system - ie where an air bubble in the hot water tank divides the central heating water from the hot water supply)? Any ideas how much I'll have to pay for having the pump replaced?

Thanks, John

[Frank Erskine]

I have a spare 2-130 in good condition, which you're welcome to have. The only problem would be getting it to you, John.

[Tony Bryer]

Virtually all pumps are interchangeable. Usual price £30-40, see

There seem to be

Assuming the valve haven't seized, yes.

[Andy Hall]

It shouldn't be. Most domestic pumps have a standard spacing between the flanges of 130mm and a standard flange size of 1.5" BSP male.

Other pump sizes are available so it should be easy to find one to match.

It should be possible to replace the pump without draining the system provided that the isolating valves can be turned. It is possible that they will have seized and will need persuasion with WD40 and suitable tool. In the worst case, the valves would have to be replaced.

Replacement pumps come with fibre or similar washers for the valve unions.

Cheap pumps start at about £25 for the pump. It's worth paying £40-45 for a good quality one like a Grundfos.

and search using "circulator" as a keyword.

You will also find pumps in larger DIY stores and plumbing/heating merchants.

It's an easy DIY job, but allow time and access to supplies.

Alternatively, heating engineer call out rates seem to start at around £45-50 including so much time. If there were no snags like having to drain, then I would have thought it's no more than a 30 minute job.

[John]

Thanks, Frank. I've heard that older pumps are better quality than more recent ones, so this may be a good idea - I don't suppose you live anywhere near the Wirral?

John

[Frank Erskine]

No - I'd have to post it. If you like I'll find what postage would cost. It weighs about 8 lbs, plus packaging....

email if you are interested.

[Dave Liquorice]

And actually isolate well enough. If they are the gate type the chances are that they won't close fully and you'll have leak a nasty black stainy stuff under 10 to 30' head of pressure.

Even if they do shut and isolate you then have the problem of the flanges not wanting to part company with the pump.

Changing a CH circulator should be a 30min job tops, it rarely is...

[Roly]

I had exactly the same problem about a month ago. I bought a lovely Grundfos pump, but then discovered that I didn't have big spanners suitable for undoing the nuts on the flanges.

I contacted a local plumber and assured him that there were isolating valves, I had the whole job prepared and he only needed to do a bit of spanner work. He called in on his way home, asked for £25 in cash and was on his way in well under twenty minutes.

[Nick Atty]

Took me about three hours yesterday from coming in to a cold and electricity-less house to being back up and running. The pump had failed well enough to trip the RCD.