how to undo a tough nut

mr218

situation is thus. the pump of our central heating system died last week. seemed very straightforward to replace it. ordered an identical replacement and my husband tried to undo the nuts which are fixed to the top and bottom flanges of the old pump. but try as we might we just cannot budge it. he put WD40 overnight, heated it locally with a heat gun, used his strength (he is 6'4" and reasonably strong), but nothing.

my regular plumbers are not available till december. I am wary of getting a cowboy to replace it. It seemed like a straightforward job but these nuts are doing my head in. my husband is aware that if he goes really all out the pipes around the pump will get warped and there will be a greater problem.
we moved into this house just a few months ago and have not yet ventured into the loft, where the water tank is. the only solution seems to me that a plumber has to come and drain the water out of the system and cut the pipes to remove the old pump and then weld a new piping and pump assembly. This will probably cost a lot as well.

so if anyone has any bright ideas or suggestions we can try, i would appreciate it. could really do with saving the money from calling a plumber
thanks
meera

intel

Get a small hammer and gently tap the nut all around then put a spanner on
the nut then put a bar over the spanner to make more leverage and then
give it a sharp push, make sure you push the correct way as it could be
an opposite thread. So it really comes off clockwise, I would check.

Paul_the_Painter

Try using a pencil gas torch £3 from my local market on the nut, a heat gun will heat up the whole thing, what you are trying to achieve is heating the nut, but not what is screws onto. so very localised heat and very hot for a short time is what you need. Failing that draining down the system is not a huge task, turn off supply in loft to the central heating header tank (or tie up ballcock), one or more ground floor radiators will have a drain plug on it, connect a garden hose and open with a radiator key, go to rads at highest point in the house and open vent to to let air into system so that the water drains out quickly. System is now drained. Fit new pump (no need to weld/braze use compression fittings available at your friendly Bodge & Quit) whilst your there buy a length of copper pipe as when you cut off the original fiitings(use a pipe cutter) you will need to make up the length. Once pump is fitted close off drain plug and refill system, then go round all radiators in the house will a radiator key letting the air out of them. Job done

p.s. don't forget to put some inhibitor in the system whilst you are filling it up to protect it. (Fernox etc.)

uncle_buck_3

If the replacement pump is exactly the same why not just use the new pump head on the old pump body, this way you won’t have to undo those tight pump unions!
Just undo the 4 allen head bolts & give the pump head a tap to free it.

& Just in case anyone out there thinks this is a cowboy method…most central heating spare part suppliers sell replacement pump head units! & this practice is actually recommended by Potterton when replacing the pump on one of its boilers (Puma if I remember correctly) that has limited pump access.

Regards

tomstickland

Heat and impacts are no1 nut loosening methods. Hammer and punch and hit it hard in a number of places. Next you want a decent large spanner to fit it. Failing that, use a Stilson (pipe workers adjustable graunching spanner). These are great because they dig themselves in harder and harder. A lump hammer on the end of the Stilson isn't elegant but it will undo most things.

Fraserca

You may have to face up to the fact that the nut wont move. Can you cut the pipe and put in an extension to meet the new pump?

mr218

thanks for all your suggestions. we will work through them and see where we get.
the cold is making us dormant and we just vegetate in front of the portable heater ;-).

thanks again

meera



i

tomstickland

calmgirl

try tightening it up just a few degrees first there is a tape undernetah the nut to form a seal and heating it will make his expand and hence get tighter. there should not be a reverse thread on the nut as this has no purpose ie Bike wheel.

wolvesinwales

I can endorse what calmgirl has calmly advised, tightening it slightly can break the stubborn hold, i learnt this a few years ago when trying to get some part off my car.

robowen

If its not too late to put in a suggestion....

...why not cut out the pump before and after, and reconnect with new pipework.

rob