What size are the NUTS on Grundfos 15-50 pumps ?

[boogsy]

pump nut spanner is made by MONUMENT and is available at any decent plumbers merchants and if they are too much of pain just cut em off and replace them unless you have loads of times to faff around

very crafty !

thats a good idea , cutting the nut off, and leaving the threads intact.....

great info

thanks for all the info about the spanner / wrench types, this is all new to me....

 

[Homesafe]

If you cut the nut off the pump how would you put the new nut on?

I don't understand that method.

 

[ChrisR]

If you cut the nut off the pump how would you put the new nut on?

I don't understand that method.

The pump nut is a hex at the front and a ring at the back, right?
Well the ring has a couple of cutouts in it so you can get it over the flange on the valve body.

The thread is 1 1/2 BSP, so the nuts were originally defined as 2 1/16th inch. But yes, 52mm will do.
If you can't get pump nuts undone, whack the points of the hex ( I know, they're always stupidly rounded even when new) with a hammer, in the undoing direction. It always seems to unstick them.

Failing that, make a nick in the nut with a hacksaw blade - which is often all you can reach with. A hammer and sharp cold chisel in the nick will often undo them if hit in the right direction. If no go, cut through. Remember the threads are NOT what make the seal so it doesn't matter if you cut into them.