Having just finished flushing my central heating system and filling with inhibitor the time came to fit the new rad. That's when I realized the TRV would not close (I had capped of the valve outlet during works).
I had to think of something to get me out of trouble without re draining again and losing the inhibitor, not all TRVs come with a closing cap i.e. the Danfoss click on type.
So here's what I came up with, a little tool made from a section of vertical blind track and bolts that will positively close the valve after the TRV has been removed by holding the valve pintle shut, it needs a small indent in the end of the closing bolt.
You have all guessed by now that I am not a plumber but I think I will keep it just in case.