Radiator inlet valves and TRV

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I removed my old radiators while plasterers replaster my walls and isolated the valves come from the copper pipe. It’s a 15mm copper pipe that has an olive and compression nut. Instead of refitting the old knackered radiators that look very tired, I bought new ones matching the same size. I want to buy new valves too where I can drain the system then remove the compress nut and retain that along with the olive but then just replace everything else to the radiator. But I don’t know what size valves I need for the but that actually needs to go into thread of the radiator. The radiators spec says 1/2” inlet.

I want to try and get valves that don’t protrude out to much as it needs to come out of the radiator and have a 90 degree bend without protruding out too much otherwise the pipes may not line up.

Also previously it had no TRV and I’m thinking to add a TRV on each one but as the radiators are completely off I can’t do the feeling test to find out which is flow and which is return to determine which end to put the TRV. Any suggestions? Are there TRVs that work on either side?

Thank you
 
3 things jump out straight away -

1) if you get bidirectional TRV's then it doesn't matter what side they are fitted
2) were the radiator balanced?
3) depending on how old the valves were will determine if modern valves will fit. If they were reasonably old then the threads may be different. Also their reach into the valve may be different therefore removing the nut and olive may be required. Also depending on the condition of the olive may cause trouble too, if badly compressed then the olive will need replaced.
 

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