One of our radiators has stopped working completely; ie not a trace of
warmth when the CH is on. First port of call was an investigation of
the valve, suspecting that its pin might be stuck down; however it
definitely isn't, and it's currently in the fully 'out' position with
the valve head removed, and the rad's still in Witches' Tit mode.
So - is it possible the valve still needs replacing? Or am I looking at
a blockage (or, unlikely, an airlock) somewhere?
The jumper (that the pin pushes down) can stick to the valve seat. There's
no solid link between pin and jumper. I usually give the valve body a sharp
tap with a hammer/spanner/whatever comes to hand and that seems to free it
currently working on 4 new builds and had this problem with one rad in each
house - the same one in each house for some reason - all the rest were
glowing and this one wouldn't get warm.
Left heating on and turned all other rads off and it got hot, then went
around and turned all other rads back on and now they all work fine, we did
get a bit of air out of the one on the third floor so it was probably an
The cold rad was on the ground floor only 5m from the boiler, yet the 'loft'
one got heated up fairly quickly
No, the pipe run was a metre up from boiler, about 3m across a ceiling and
2.5m down a wall, not much different from the other two downstairs ones,
then there's 3 on the middle floor and one in the loft room.
Boilers are glow worms, 26k I think.
They all seem to be fine now, I've a feeling there was a 'U' in the pipe to
this rad - it's all done in plastic and it was coiled, so it could be an
undulation where they were drilled through the joists
This is what I wrote a long time ago:
I have attacked mine several times in the following way, without
draining the system, and no more than a dribble of leakage.
Having unscrewed the dome, prod the pin which protrudes from the
valve a few times. Mild jams can be cleared this way.
If it is still stuck, first get some old cloths or towels to
catch any spillage. Remove the circlip and lift out the plate
through which the pin passes. Beneath is a rubber diaphragm,
which may or may not come with it. Remove it, taking care not to
tear it. Water may start to well up in the valve body. Insert a
screwdriver into the body, of a suitable size so that it is a
fairly tight fit. A mixture of jabs and twists with the
screwdriver should result in it freeing the mechanism. You will
feel the spring release, and the valve will be free to move
Now you have to get things back together. Replace the rubber
diaphragm, replace the plate with pin protruding through. Now
comes the hard part - get the circlip back. Some of my valves
have had this done so many times that I really don't want to
disturb them again.
If this still does not work, then you will have to drain down,
and get right into the valve to persuade the parts to move
I had all the valves replaced a few years ago, when I had a new
boiler, fresh inhibitor was added, and they haven't needed any
Chris J Dixon Nottingham UK
Thanks for this. Don't you at least have to depressurise the system to
do this? As in, when this circlip comes out won't the system otherwise
'self-depressurise' rather rapidly at that point?
Thanks for the tip - I attempted a good old 'dunt'ing yesterday, but
alas to no avail.
(At least this is the spare room rad - normally set to 'off' anyway;
which is probably the root of the problem...)
If the pin springs back up when you push it down and then release it,
the valve is probably ok. You can check that it's passing water by fully
shutting the lockshield valve and then opening the bleed screw. If
water squirts out, water must be flowing through the valve (unless the
lockshield is duff and not shutting fully - but let's assume that the
lockshield is ok). If air comes out, keep it coming until water starts
to come out (and then top up the system to the correct pressure). For
completeness, close the TRV fully (preferably with a decorating cap),
open the lockshield and re-bleed - to ensure that that side of the
circuit is working.
Having proved that water is flowing through *both* valves, if the rad
still doesn't get hot, you've probably got an air lock. The usual trick
here is to turn off all the other rads, turn the pump up to max speed -
if adjustable - and run the system for a bit. That should clear any air
lock, and the rad should get hot. After that, it should continue to work ok.
 Count how many turns are needed to close it, so that you can restore
it to the same position (assuming that the system has ever been balanced!
As I finally got round to sorting the above out at the weekend (during a
system drain-down necessitated by installing a new rad elsewhere in the
house) i thought I'd just report back (always good to hear the outcome,
innit?). Thanks Roger for the sensible how-to-do-it.
Upon investigation I found the lockshield valve was completely shut off,
which would of course account for the completely cold radiator. WTF?
Then - lightbulb moment - I suddenly remembered that *last* winter I had
a problem with this rad (which is in a little-used spare room) not being
possible to turn *off*: ie with the TRV set to minimum the rad was
still warming up and keeping the empty spare room warm all winter. So I
shut down the lockshield valve and made a mental note to sort it out
come the summer. HTF did I just completely forget that? Well scary. :( :(
Fortunately the grey cells are still up to swapping out a failed TRV,
which I duly sorted out...
"Mental note", yep, been there, too! I'm 66 and now have to make
written notes if I want to remember anything important. Pi**es me off,
but if I try to remember important stuff, I just forget. And yet I can
cast my mind back to age eight in Hastings in the 1950s and remember
loads of details of my everyday life.
By the way, if you start jotting down "reminders", always make a
mental note to where those reminders are, else you'll never find 'em
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.