Best Isolating valves for Central Heating Pumps??

Hi everyone,
I'm looking for advice on the "best" way to isolate my central heating pump
6 years ago I had 22mm pump valves fitted (these are the guys that compression fit to the 22mm pipework, & then fit directly to the pump flange with a (removeable from the fitting) large diameter backnut with a sealing washer.
The pump failed over the weekend so I popped out, bought a new one & then couldnt undo one of the backnuts. - I'm told this isn't unusual - & I think I'm going to have to split this backnut to get the pump off
So 2 questions -
1 how can I remove the backnut from the pump - I can swing the isolating valve & pump around the olive on the 22mm pipework! So the backnut/washer/pump face are really tightly together! Ive tried bashing the pump motor housing with a copper mallet while holding the isolating valve body with mole grips - no good! There must be a magic way but I haven't thought of it yet!
2 & what would you fit as isolating valves - are handle operated 90 degree ball shut off valves any good over long periods of time?
I hope I've managed to explain the problem enough for you to understand what I'm dealing with
TIA for any advice
Frank Sweeting
Frank Sweeting
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Frank Sweeting wrote:

Have you tried heating the nut with a blowtorch for a bit? - a few heating cycles can help break the bond. You could also just cut of a short section of copper pipe either side and replace the isolating valves at the same time.
Failing that you could split the nut off - nut splitter or a metal cutting disc in a dremmel type tool.

Not bad - if you get ones that do not restrict the flow rate (and hence introduce extra water hammer noise).
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Cheers,

John.

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This is what worked for me, though I used an electric paint stripper.
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On Wed, 01 Oct 2003 18:49:56 +0100, Frank Sweeting

I've used lever ball valves and found them fine over a 3 year period so far.
Certainly they are better than gate valves.
.andy
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Yes. I've had no problem with the pump, but have had to drain the system down twice to fix the gate valves, which are only there in the first place so you don't have to drain the system down. Seems to be a logic fault there somewhere?
--
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On 1 Oct 2003 20:09:56 GMT, snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote:

Exactly.
I've found the red wheeled ones to be bad enough - they stick and are difficult to move when it's necessary to turn them off, and even when closed they seep or even drip quite fast.
The ones that are built into pump unions are even worse, and I've found that they can be very hard to move. You don't really want to have to mess around with WD40 etc. and leave to soak when a pump needs to be changed.
Ergo, last time, I put unions with compression fittings next to the pump and then lever ball valves next to them.
Completely effective.
.andy
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Andy Hall wrote:

Yup, same here, after learning the hard way that the standard pump gate valves are a curse. A curse I tell ya.
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Frank Sweeting wrote:

The 'magic' technique uses a large lump hammer as an anvil and your copper mallet. Put the lump hammer onto a flat of the of the ring nut but towards a corner. Whack the opposide face/corner with the copper mallet. Try both directions - to get some movement into the ring - the inertia of the pump body does half the work. The lump hammer protects the pipework.
Some penetrating oil round the ring will help. Put silcone grease on reassembly either you or someone unknown will thank you in the future.
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Ed Sirett - Property maintainer and registered gas fitter.
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Ed said: "Put silicone grease on reassembly either you or someone unknown will thank you in the future"
This is fantastic advice - always consider the future dismantling. Some lubrication will always help. When I moved into a new house I dismantled my taps and lubricated the mechanism and threads - they still work as smoothly as new and are easy to dismantle if I need to replace washers. Likewise - my garage door was well lubricated from new - many neighbours have had theirs replaced due to breakages. At one time everyone had an oilcan. Now they seem to be rare. Also a bit of Copperslip on the screws on the C/H boiler ensure easy dismantling for servicing.
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Regards

John

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Thanx to all for your helpful comments
Regards: Frank Sweeting
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