Radiator & valve replacement

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The radiator in my bedroom isn’t that hot compared to others in the house. It’s hotter at the top than it is at the bottom but the top is nowhere the temp of other rads in the house at the top.

I think I’m going to replace the rad & the valves either end but the valves are the style attached in photos.

I can do most things but I don’t want to drain the boiler down.

Changing it will not be hard for me but when one valve is off how can I stop the water coming out the pipe that pops up through the floorboards.
 

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Drain the system to a lower level than the radiator you intend to work on. Trying to remove a valve when the system is full of water is something professionals can do ,but diyers are safer draining.
 
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The radiator in my bedroom isn’t that hot compared to others in the house. It’s hotter at the top than it is at the bottom but the top is nowhere the temp of other rads in the house at the top.

I think I’m going to replace the rad & the valves either end...
Of course you are free to do that, but what makes you think a new radiator will perform any better than the old one?
Have you removed the TRV head and inspected the TRV actuation pin for free movement? It could simply be that it's stuck (nearly) closed.
 
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Of course you are free to do that, but what makes you think a new radiator will perform any better than the old one?
Have you removed the TRV head and inspected the TRV actuation pin for free movement? It could simply be that it's stuck (nearly) closed.

Point taken.
I have not removed the TRV so is it just a matter of turning it & then it unscrews ?
If so i should see a pin,do i then need to see if when i press it that the pin moves ?

Thanks
 
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Correct. Most pins will move 3 to 5mm. Use a flat bladed screwdriver to press the pin.
Then I (and I think most other contributors) would like to know the outcome of your actions, whether it was successful or not....we have egos too.

MM
 
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So I’ve just taken the TRV head off & I can press the pin down. When I press it down I hear a noise I suppose of the water passing the part of that pipe work.
Looking at the part I removed I can see when turning to number 5 it would then be pressing down the pin all the way.

The other end of the radiator has just a flat piece under the white cap.
Turning this a little I then see water starting to appear around the threads etc.

Leaving it like this for 15 minutes the radiator is still much warmer / hotter at the top compared with the bottom.

The bottom isn’t cold but let’s say,
TOP 8/10
BOTTOM 3/10
 
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Assuming that by "... flat piece under the white cap..." you mean a flat on the end of a vertical spindle, your are talking about a lock shield valve. Then:
1. Nearly every radiator will have a lock shield valve at one end, and a TRV or manually adjustable valve (wheel head valve) at the other.
2. The lock shield is used one time to govern the maximum flow of water through the radiator.
3. The TRV / manual valve is used to adjust the flow from zero to the maximum set by the lock shield.
4. Your lock shield valve should not be leaking just because you have turned the spindle. It shouldn't be leaking at all.
5. It may be that it has leaked in the past, so someone has shut it fully to stop the leak. If this is the case you may need to replace it. If it has a gland nut (small hexagonal nut with the spindle passing through it, situated on top of the body of the valve) you might be able to re-pack and tighten the gland nut and stop the leak. If the spindle is sealed by O rings in the body, you will need to replace it.
6. As other have said above, to change a valve you will need to drain the system down to just below the level of the valve to be changed. There are ways of doing it without draining down, but they require experience and / or special equipment to do it safely.
 

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