I think I already know the answer to this one, but just wanted to make sure.
I have a leaking valve on one radiator (not the TRV) which only causes
problems if the system is pressurised and used. If I turn the TRV right
off, I should be able to use the rest of the CH system without risk of
further leakage until I can get the issue fixed by someone a little more
competent than me.
Any advice gratefully received!
Try it and see....
In practice once the system is pressurised and used there will be pressure
at both valves on the radiator, so just turning off the TRV is unlikely to
solve your problem. Can you see where the leak originates? There are
probably three places a valve can leak.
1. Where the valve connects to the pipe.
2. Where the valve connects to the radiator
3. From the stem of the valve (ie the bit that turns)
If the leak is from 1 or 2 you may be able to solve it simply by tightening
the appropriate nut, an eighth or quater revoloution turn with a spanner may
be all it needs if its just a drip, but take care that the valve is
supported before you do this otherwise you can twist it and make things
If its leaking where the valve connects to the radiator turning off both
sides may solve things, but only after all the water in the radiator has
If the stem is leaking you may find that the leak stops if the valve is
actually fully open, rather than partially open
Probably not. Have you examined the lockshield valve to check where it's
leaking from? If the top, it may be possible to sort it by just tightening
the gland nut - that's the nut which fits round the spindle underneath the
pull off cover.
*And don't start a sentence with a conjunction *
Dave Plowman firstname.lastname@example.org London SW
Depends where the valve is leaking from and whether you turn that off as
well. Just turning the TRV off achieves nothing other than a cold
Depending on the age of the valve the stem gland (the most likely source
of a leak) will be sealed either by an O ring or by hemp and tallow (or
their more modern equivalents). Judicious tightening of the gland nut
may seal the leak before the valve gets too tight to turn but if the
seal is an O ring you may be out of luck. The (no doubt cheap and nasty)
ones I have on some radiators have no capacity for tightening. The gland
nut merely retains the O ring.
No, because the flow is pressurised and if other rads are in use then the
return is pressurised and therefore turning off the TRV will have no effect.
If you want the simplest possible fix. Crimp the feed pipe to the
lockshield good and hard and as flat as possible at least 2 inches from the
lock shield. This will be easier with less than 15mm pipe but will reduce or
stop the leak. Then your plumber can rectify. Of course if this goes wrong
and you split the pipe (unlikely) you will be in a right mess!
I would be very surprised if crimping the pipe in situ would stop a leak -
it would reduce full bore flow down to a trickle but to stop a drip ?
then the section would need to be cut out and replaced - might as well
drain, cut out, replace ASAP I reckon
It would reduce the pressure drastically and hence stop a drip.
For example if you operate your CH at 1 bar like an indirect system and then
swap over to direct combi system and run it at 2 bar then you are very
likely to see leaks that were never a problem before.
If you hold your hand over the cold tap and turn it on a little you can stop
the flow completely, if you turn it on full bore your hand is unlikely to
produce a satisfactory seal. All seals are good up to a pressure X, when X
is exceeded the seal will fail, period.
My solution is entirely appropriate for the OP who sounded like he wanted
the simplest solution whilst waiting for a plumber.
Oh dear....... seems like you are confusing flow and pressure -
the pressure at a pin prick hole in a pipe is the same as at the
end under static or near static conditions
If you put your finger over the end of a tap on a high pressure
pipe, it will be just as easy to stop (or not) whether the tap is fully
open or just a tiny bit. Period.
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