A question about the central pin in the thermostatic head of for
instance

https://www.screwfix.com/p/drayton-r...ing-head/3279r

One of my radiators is not coming on. I've taken the head off and if
I rotate the top part (ie hot to cold) the central assembly doesn't
move though I can push it in with a screwdriver and it springs back
but seems to require more pressure than I'd expect the little pin in
the radiator valve could exert.

I've tried a working head from another radiator and the pin retracts
as I go to 5 and protrudes as I go to 0.

So how should it operate and if faulty should the item referred to fix
it?

The pins in both radiators are free and can be pushed down (= off?)



--
AnthonyL

Why do scientists need to BELIEVE in anything?

Although the pins move up and down I think sometimes the sealing washer sticks to the seat.

A sharp rap to the side of the valve body with a small hammer can sometimes shock the jumper off its seat but this is only a temporary repair once its started sticking in my experience.

Tim

Have you checked that the lock shield valve on the opposite end is in the on position?

On Wed, 25 Sep 2019 05:48:33 -0700 (PDT), "Tim+"
wrote:

Although the pins move up and down I think sometimes the sealing washer sticks to the seat.

A sharp rap to the side of the valve body with a small hammer can sometimes shock the jumper off its seat but this is only a temporary repair once its started sticking in my experience.

It's the valve head. Take it off and the radiator works. As in my OP
I think the central column is not moving as it should.

--
AnthonyL

Why do scientists need to BELIEVE in anything?

On 25/09/2019 11:22, AnthonyL wrote:
A question about the central pin in the thermostatic head of for
instance

https://www.screwfix.com/p/drayton-r...ing-head/3279r

One of my radiators is not coming on. I've taken the head off and if
I rotate the top part (ie hot to cold) the central assembly doesn't
move though I can push it in with a screwdriver and it springs back
but seems to require more pressure than I'd expect the little pin in
the radiator valve could exert.

What is the ambient temperature of the room or within the TRV haed when
in your hand whilst testing it? If its close to 29C then the wax in the
TRV head will have already expanded close to its maximum to shut off the
valve. First mark the position of the mechanism and then put the TRV
head in the fridge for 5 minutes before checking the position again.

There will be a lot of force pushing back when you try and compress the
wax in the TRV head with your screwdriver if the wax has already
expanded due to a temperature approaching 29C

When the valve head is reinstated it may only fully open the valve if
the temperature is below 12C. Any temperature above this and the valve
will already be closing down and at, say, 20C it may be 50% to 75%
closed. If in this sate the radiator is not getting hot then the system
may not be properly balanced. In my experience balancing the system in
hot weather that have TRVs is difficult and if I do any work on my
system during the summer I wait until a really cold spell to fine tune
balancing.

It may be possible to fit the head scewed. On a similar head I've found
that I have to push it down quite hard to properly seat the valve base
before doing up the silver ring/screw.


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

Yes there are two radiators like this in a room we rent for the talking
newspaper, in the main the one working one is sufficient, but occasionally
in really arctic weather it would be nice to get one going. The building
manage could not give a xxxx of course.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Tim+" wrote in message
...
Although the pins move up and down I think sometimes the sealing washer
sticks to the seat.

A sharp rap to the side of the valve body with a small hammer can
sometimes shock the jumper off its seat but this is only a temporary
repair once its started sticking in my experience.

Tim

On Wed, 25 Sep 2019 21:57:21 +0100, alan_m
wrote:

On 25/09/2019 11:22, AnthonyL wrote:
A question about the central pin in the thermostatic head of for
instance

https://www.screwfix.com/p/drayton-r...ing-head/3279r

One of my radiators is not coming on. I've taken the head off and if
I rotate the top part (ie hot to cold) the central assembly doesn't
move though I can push it in with a screwdriver and it springs back
but seems to require more pressure than I'd expect the little pin in
the radiator valve could exert.

What is the ambient temperature of the room or within the TRV haed when
in your hand whilst testing it? If its close to 29C then the wax in the
TRV head will have already expanded close to its maximum to shut off the
valve. First mark the position of the mechanism and then put the TRV
head in the fridge for 5 minutes before checking the position again.

There will be a lot of force pushing back when you try and compress the
wax in the TRV head with your screwdriver if the wax has already
expanded due to a temperature approaching 29C

When the valve head is reinstated it may only fully open the valve if
the temperature is below 12C. Any temperature above this and the valve
will already be closing down and at, say, 20C it may be 50% to 75%
closed. If in this sate the radiator is not getting hot then the system
may not be properly balanced. In my experience balancing the system in
hot weather that have TRVs is difficult and if I do any work on my
system during the summer I wait until a really cold spell to fine tune
balancing.

It may be possible to fit the head scewed. On a similar head I've found
that I have to push it down quite hard to properly seat the valve base
before doing up the silver ring/screw.


It's autumn. It's the UK. It's time for the CH to come not the
AirCon

The central column in a working head moves up and down just fine.


--
AnthonyL

Why do scientists need to BELIEVE in anything?

alan_m wrote in news:gv22lgFo4r5U1
@mid.individual.net:

It may be possible to fit the head scewed. On a similar head I've found
that I have to push it down quite hard to properly seat the valve base
before doing up the silver ring/screw.


Good point: On mine the head can only seat in 6 positions - some sort of
hexagonal seating.

On Wed, 25 Sep 2019 21:57:21 +0100, alan_m
wrote:

On 25/09/2019 11:22, AnthonyL wrote:
A question about the central pin in the thermostatic head of for
instance

https://www.screwfix.com/p/drayton-r...ing-head/3279r

One of my radiators is not coming on. I've taken the head off and if
I rotate the top part (ie hot to cold) the central assembly doesn't
move though I can push it in with a screwdriver and it springs back
but seems to require more pressure than I'd expect the little pin in
the radiator valve could exert.

What is the ambient temperature of the room or within the TRV haed when
in your hand whilst testing it? If its close to 29C then the wax in the
TRV head will have already expanded close to its maximum to shut off the
valve. First mark the position of the mechanism and then put the TRV
head in the fridge for 5 minutes before checking the position again.

There will be a lot of force pushing back when you try and compress the
wax in the TRV head with your screwdriver if the wax has already
expanded due to a temperature approaching 29C

When the valve head is reinstated it may only fully open the valve if
the temperature is below 12C. Any temperature above this and the valve
will already be closing down and at, say, 20C it may be 50% to 75%
closed. If in this sate the radiator is not getting hot then the system
may not be properly balanced. In my experience balancing the system in
hot weather that have TRVs is difficult and if I do any work on my
system during the summer I wait until a really cold spell to fine tune
balancing.

It may be possible to fit the head scewed. On a similar head I've found
that I have to push it down quite hard to properly seat the valve base
before doing up the silver ring/screw.



I think the penny is dropping slowly. There are at least two types of
valve head. One which is purely mechanical so the user has to turn
the knob to allow more or less heat through the radiator. The other
is thermostatic so it attempts to stop the room from getting warmer
than it is set to. Is that right?


--
AnthonyL

Why do scientists need to BELIEVE in anything?

On 27/09/2019 17:38, AnthonyL wrote:
I think the penny is dropping slowly. There are at least two types of
valve head. One which is purely mechanical so the user has to turn
the knob to allow more or less heat through the radiator. The other
is thermostatic so it attempts to stop the room from getting warmer
than it is set to. Is that right?
Yes. The latter is called a TRV, Thermostatic radiator valve.
In general a wax cylinder exapands and pushes the pin to cut off the rad
at a given point



--
€œI know that most men, including those at ease with problems of the
greatest complexity, can seldom accept even the simplest and most
obvious truth if it be such as would oblige them to admit the falsity of
conclusions which they have delighted in explaining to colleagues, which
they have proudly taught to others, and which they have woven, thread by
thread, into the fabric of their lives.€�

ۥ Leo Tolstoy

On Fri, 27 Sep 2019 17:46:51 +0100, The Natural Philosopher
wrote:

On 27/09/2019 17:38, AnthonyL wrote:
I think the penny is dropping slowly. There are at least two types of
valve head. One which is purely mechanical so the user has to turn
the knob to allow more or less heat through the radiator. The other
is thermostatic so it attempts to stop the room from getting warmer
than it is set to. Is that right?
Yes. The latter is called a TRV, Thermostatic radiator valve.
In general a wax cylinder exapands and pushes the pin to cut off the rad
at a given point



Thanks, on my non-working one the cylinder does not change position as
I turn it. On a working one the cylinder does.

On the presumably non-thermostatic one the central pin is clearly on a
thread and just goes up and down with the rotation of the head.

I've not been careful enough about which type to select and which ones
are best installed in which rooms. With my new-found education I
shall save vasts amount of energy and help save the planet.


--
AnthonyL

Why do scientists need to BELIEVE in anything?