On 19/12/2012 22:10, John Rumm wrote:

The right way is the wrong way (if you see what I mean) because the nut
unscrews from the valve towards the radiator, with a right hand thread.
It is as if you were trying to screw something into the radiator.

It does depend on the valve though... some have a traditional cone joint
where the nut is retained on the rad tail and screws onto the valve.
More recently the tails seem to simply have a protruding length of
chromed 15mm Cu pipe, and the valve in effect has a normal compression
fitting that tightens onto the pipe stub. Needless to say they undo in
the other direction.

(the new sort allow a little lateral adjustment of the valve relative to
the rad)


Excellent point, I have just fitted a couple of these myself. But they
do seem to be a relatively new development. Very valid points also about
gripping valve and providing reaction force to radiator.

But to repeat earlier point, I have been pleasantly surprised how
linseed oil based sealants do soften up on heating.