On 14/03/2021 15:02, John Rumm wrote:
On 14/03/2021 11:34, RJH wrote:
Just noticed one of the TRVs leaking - from the pin. Tried various
thumps,
twists and tightenings, but it's still weeping a little. In my spares
box I've
got a number of TRVs that I've 'improved' over the years, but they have
different markings and part numbers.

They both have arrows in both directions, so bidirectional I'd guess.
But they
have different part numbers (that resist google), are marked 'GB', and
different symbols. One looks like a comb (radiator?), and one looks
like an
inverted 'U':

https://www.icloud.com/sharedalbum/#B0z5idkMwmb0Bb

Are they the same thing? They were fitted at the same time by a
plumber who,
when fitting a new boiler, uprated the valves to comply with regs.

Look pretty similar from here. Both obviously TRVs, which is a good start!

I'm going to try a quick swap without draining the system down - just
emptying
the radiator and taking out as much pressure as I can. Wish me luck :-)

You need to dump the pressure from the pipework as well - only normally
takes a few litres to do that (depending on the size of the expansion
vessel).

I normally find pushing the body of the valve against the pipework[1]
while you get the lock nut fully undone helps control any leakage, then
you can whip it off fast and get a thumb over the end of the pipe (or
swap directly to the new one).


[1] If the rad tail comes up through a suspended floor there is always
the chance it will drop down when no longer supported by the connection
to the rad - that can introduce an extra element of "complexity" to the
process of a live swap. So I normally clamp my vice grip spanner on the
pipe at floor level so that it can't move down.


A WET (& DRY) Vacuum cleaner can do wonders in capturing any escaping water.