Tim Lamb wrote:

In message , Roger Hayter
writes
Tim Lamb wrote:

In message , Mr Pounder Esquire
writes
John Rumm wrote:
So far all the normal tricks don't seem to be doing it!

Short version:

There is a leak somewhere in my central heating system - its losing
pressure regularly, and needs topping up with at least a couple of
litres a day.

Snip. Not being rude. I was losing water. The loop valve was not
turned off properly, even though it looked okay.

Further news on my leak.

Isolating the floors showed the leak was upstairs! Slight wet patch
showing below the manifold cover.

Water drip from the *plumber fitted* mixer valve! Basically the threaded
spigot on the valve was too short to seal against the fibre washer
inside the 22mm coupler. The joint was garmed up with plumbers mait.

Agricultural solution plus lots of ptfe tape...... we'll see how it
goes.
Could you just saw a few mm off the nut?

You were right. The agricultural solution failed once the hot water
reached the manifold.

I have shortened the coupler by turning off the spanner flats.
Fortunately I have a set of *Mole* grips with curved jaws which were a
good fit on the remaining body. More mait and it was running OK last
night.

Yes, tap connectors are horrible things. I was forced to use them
behind a siliconed-in tile and have had nothing but trouble. Usually
due to rigid pipework not lining up 100% so the washer is unevenly
compressed. Gross over-tightening seems the only solution. If there is
room, a tapered, sealed threaded connection with a nearby compression
joint for dismantling is more reliable. Or even a proper union
connector to be posh!


--

Roger Hayter