Pressing the pins down seems to have loosened them up and they are
"currently" working but I suspect it is just a matter of time before
they stick again!

Thanks.

Paul.



"Set Square" wrote in message ...
In an earlier contribution to this discussion,
Milleniumaire wrote:

The central heating system in the house that I bought as new 5 years
ago is fitted with Pegler Terrier II thermostatic radiator valves.
About a year ago I noticed that on a couple of radiators even when the
valve was turned off (* setting) the radiator remained hot so I
assumed the valve had failed and replaced both valves. Having just
drained the system and refilled it with Fernox cleaner I have noticed
that another 3 radiators are staying hot when the heating is on
regardless of whether the valve is turned off or not! It seems that
the small pin is not being pushed down by the head. I have tried
swapping the heads with heads from other radiators which are working
okay but this doesn't seem to make any difference. This confuses me
as I thought the problem was in the head not in the valve (the part
connected to the radiator).

Can anyone explain how these valves work and what is going wrong? Is
there any way of repairing them or do they need to be changed? Have I
got a bad make and need to switch all the valves before they continue
to fail (I would rather resolve the problem in one attempt rather than
spend the next 5 years having to change individual valves as they
fail).

Thanks in advance for your advice.

Regards.
Paul.

Have you tried removing the heads and pressing the pins down manually? This
should unstick them if they are stuck. The bellows in the TRV can't exert as
much force as you can! Many of these valves are supplied with an alternative
(manual) head - for turning the valve off positively when decorating etc.
Have you got any of these? If so, what happens when you fit one and screw it
down?