CH Pump

[Wesley]

Our CH pump started making funny noises this evening. I hit it with a hammer but this only resulted in changing the tone of the noise. It seems to work OK when only the hot water is switched on but when I switch on the heating to the rads, the noise starts. The pump is a Myson, Unit 5, Code

1187 USC 252.

Is there any way this can be repaired? I'm guessing that it's at least 25 years old and is the original pump that was installed with the CH system by the previous owner.

Failing being able to repair it, can anyone recommend a new pump that would have inlets and outlets in the same place so I would not have to alter the pipe work when replacing it?

[brass monkey]

Only 25 years old? They just don't make things to last any more. Hit it harder with the hammer ?

[Ericp]

You should have valves on each end of the pump which enables it to be removed and replaced. The pump should be a standard size and no alteration to the plumbing needed.

There is probably little difference between makes but Grundfos are said to be very good but pricey.

[Martin Brown]

Should being the operative word. Mine proved not to have any and also died at a suitably inconvenient time of year too. Draining the system down in mid winter with ice on the ground is no fun at all.

I don't think they bothered too much about isolation valves a decades ago - the installer figuring that he would be paid and long gone before the pump was ever likely to fail.

[Brian Gaff]

No don't. I fear it may be a take it out and see what is going on jub, in the meantime no heating.

Brian

[The Natural Philosopher]

Sometimes you can take a shaft cover off and reveal a slotted thingummybob that can be turned with a screwdriver enough to break the scale apart and get it going for a while.

If possible post a photo of it - there area lot of people here (I am not one) who will recognise the model and advise on a drop in replacement.

[Fredxx]

Any noise from a pump suggest it's turning and not seized.

[Fredxx]

I replaced my pump recently and the isolation valves were of the gate valve variety. They were both corroded and stuck so still had to drain the system down and replace everything.

[Dave Liquorice]

Try bleeding it. Remove the large screw in the end of the motor housing. Water and maybe air will come out but as a fast dribble rather than squirt have some *OLD* towels to soak it up. It may be hot, very hot...

At that age it's probably knackered, has it been bled at all in those 25 years? Must have been at some point(s) as it wouldn't have lasted that long "dry".

As others have said there should be valves immediately before and after the pump. The chances are though that they will either be ceased, not shut off or break. Even if they do work the pump flanges may well have corroded to the valves or a slight leak as caused the flange nut to cease on the valve body.

Worst case is to have to drain down and remove the pump and valves as a unit. That will involve cutting pipes and replacing sections afterwards, all day job...

Best is every thing comes undone easily the valves all work and the new pump just slides into position. An hour tops...

Pumps are "standard" you need one with the same distance flange to flange. Don't use fibre washers on the flanges use "rubber" ones lightly greased. If buying new valves get ball ones not gate.

[Roger Mills]

Is the pump, used at all for hot water, or is it a gravity HW and pumped CH system?

If it's a fully pumped system, it seems odd for it to be noisy *only* on CH.

As others have said, at 25 years it doesn't owe you a lot! Replace it.

Most domestic pumps have the same flange to flange distance - so a new pump should just slot in - except that the isolation valves will almost certainly be shot, so you're going to be faced with a partial drain-down.

[The Natural Philosopher]

No.. they hum and get hot when siezed...

[Hugh - in either England or Sp]

Ditto

Early 2010 I fitted a Grundfoss pump from Screwfix about £79 which fitted a standard opening. Claims to adjust power according to flow and pressure. Starts up very gently rather than giving the system a kick that wakes everyone up. Regret I am in Spain at present and do not have details here. Chilly day today. Only 15C.

[Wesley]

Thanks for all the advice. The hot water still works so it looks like this might be gravity fed as someone suggested. I think the best option will be to replace the pump. I've uploaded some pics to give you a better idea of the installation. There does not appear to be any way to shut off the water supply to the pump. Would it be possible to freeze the pipes before installing a new pump. Fernox was put in a couple of years ago. I'm trying to avoid draining the whole system. Any other tips welcome. e.g. pump model or any gotchas

[Dave Liquorice]

Looks like somewhere under all that corrosion are a couple of screwdriver operated ball valves. But looking at that I'd not even consider trying to use them, even if they did move and shut off the chances are they would then leak from the shaft.

Bite the bullet, drain down, hack out the pump and valves as a single unit and replace the whole lot.

On the system there are two two port valves and a white cable disappearing round the back of the cylinder (to a tank stat?) so it ought to be a fully pumped system. Is the boiler below the cylinder? It'll still work on gravity if so.

When you install the new pump take note that motor housing up like that one is not recomended, at least for grundfoss pumps. Shaft horizontal is the rule of thumb but check the instructions.

[Wesley]

I'm starting to have second thoughts about doing this myself. Have you any idea how much a plumber would charge for the job, all in?

[geoff]

In message , brass monkey writes

If that fails, an angle grinder will being you joy

[geoff]

common misconception, but there are two bearings between the water and the access hole

Yeah - as you said, they're standard and interchangeable, the distance will be the same

[geoff]

In message , Wesley writes

He might be a monkey, but he'll want more than peanuts, he can charge what he wants this time of year, if you can get one

do it yourself and learn something - even if you have to put the mrs up in a hotel for a night

[Dave Liquorice]

Well on every pump I have ever taken the plug out of the motor housing on the water comes out at what I would term a "fast dribble". OK for bleeding you only need to loosen but there is still some water loss that needs to be soaked up and CH primary water can be 'orrible black stuff that stains stuff very easily.

[geoff]

Yes, there is some water there - the motor bearings are ceramic, the water is the lubricant between them. That doesn't mean that undoing the screw is going to bleed air out of the pump. You will, however notice a slot in the shaft where you can put an electrical screwdriver to help start a seized pump

To be able to bleed air out, the bleed point has to be at the highest point - it isn't, is it?

(*you normally mount a pump horizontally, not vertically)