how to temporarily remove a radiator if you don't have decorator caps for your TRV

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I feel like this might be a really stupid question as this must happen all the time!
Moved into a new (old Victorian) house and want to temporarily remove radiators to get the wallpaper off behind.
I have a circa 1985 open vented CH system with Drayton TRV3 valves on each radiator, there is not a decorators cap for them to be found anywhere and Drayton were not at all helpful. They only have a frost setting not a true off position so I think I really need a cap.

So my query is: how do you close the TRV if you don't have a decorators cap and the new M30 1.5 ones don't fit it (I haven't actually tried a new cap I've just been told they won't).

I did wonder if I could put a brass blanking cap on but to be honest I wouldn't be sure what size to get and how feasible this is as an option.

My other thought was to just get a plumber to come and change all the valves to new ones (which I assume would come with decorator caps?) but I was hoping to upgrade the CH system in 12mths not now.

I have a spare valve left by the previous owners but the decorators cap is missing from the packet but I could post photos if that would be at all useful to anyone.

Comments or opinions on my options would be gratefully received

Meagan
 
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They will only normally leak when in a very cold room so should be okay in this weather if switched off but what I do to make absolutely sure is remove thermo head and with a pair of long nosed pliers, unscrew the brass screw in the middle a set number of turns, refit and turn off. That should do it. When finished, you can screw the brass centre screw back in by the same number of turns.
 
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They will only normally leak when in a very cold room so should be okay in this weather if switched off but what I do to make absolutely sure is remove thermo head and with a pair of long nosed pliers, unscrew the brass screw in the middle a set number of turns, refit and turn off. That should do it. When finished, you can screw the brass centre screw back in by the same number of turns.

Thank you for your suggestion - do you mean this brass screw - I assume I'm just tryin to make it stick out a bit more so it applies more pressure to the pin in the valve?
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It should not be a problem in the summer. MOTguy's idea will work, but if you do not wind back precisely the same, your settings will be off. That may or may not be a problem
Dan's will work, but may be a bit awkward to wind the head on. (Have you actually tried it Dan?)

What I would do is to wind the stat to the FS. Carefully undo the nut, and make sure there is no real pressure behind the water that will inevitably come out. Once satisfied the valve is closed, remove rad as usual. Then, belts and braces, use a 1/2" brass or iron cap to seal the valve outlet temporarily.
 
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Thank you for your suggestion - do you mean this brass screw - I assume I'm just tryin to make it stick out a bit more so it applies more pressure to the pin in the valve?
Yes, that’s it. As said, they have to go back to the same position so either count the turns or the flats on the screw so that when you have finished, it returns to how it was.
 
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Put a 5p piece or thinner betwixt head and valve pin.
also a good idea, thank you.
I am having a bit of a play trying it on the spare valve I have and I can't seem to get the thread of the ring nut to screw back on with the coin in there, it goes back on fine without. have you had this issue or should it be really straightforward?

thank you
 
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Make sure that the head is wound fully open.

You might need a disc that is slightly thinner. A trv only moves 2 or 3mm in total as it is. Only need to mitigate fraction of that?
 
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It should not be a problem in the summer. MOTguy's idea will work, but if you do not wind back precisely the same, your settings will be off. That may or may not be a problem
Dan's will work, but may be a bit awkward to wind the head on. (Have you actually tried it Dan?)

What I would do is to wind the stat to the FS. Carefully undo the nut, and make sure there is no real pressure behind the water that will inevitably come out. Once satisfied the valve is closed, remove rad as usual. Then, belts and braces, use a 1/2" brass or iron cap to seal the valve outlet temporarily.
This is more what I had in mind, the carpet will come up shortly so if I spill stuff on it I'm not that fussed. I cannot get the head back on with the coin in there at the moment despite trying every thin coin I have. There is a little number in the mounting stem I could use as reference for turns for MOTguy's idea and if I'm feeling brave I might give this a go also.

It will be a while before I have time to try this but will report back!
 
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Honestly, I’ve done it for years on mine. It’ll definately be fine.
 
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A late update:
So I turned it to frost setting and took it off with a radkit pro and sealed the TRV end with a 1/2" blanking nut and the other end took a 3/4" blanking nut. No water leaked out when I disconnect the pipes from the radiator.

Wallpaper removal went fine and the radiator was probably off around 2hrs, no leaks and the radkit was pretty good. However, when I went to put the radiator back on quite lot of water came surging out the TRV end as soon as I took the nut off to reconnect the radiator. There was quite a bit of pressure built up it seemed and my central heating was off so I really can't work out why this was. Is it normal to have this much water built up behind the nut if the heating was off? I'm wondering if I needed to turn something else off somewhere. The radiator is upstairs and is the closest to the cold water header tank if this has any bearing, all the rest of the central heating stuff is downstairs.

The nuts I used:
https://www.screwfix.com/p/blank-nut-x/51939

I have plenty more radiators to take off so I might give the brass screw turning method a go next time as well.
 

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