OK, I've just bought some TRV's for the upstairs, but they have different
fittings from the valves currently fitted.

New valves have 15mm compression fittings and tails for fitting to raditor.

Rads/old valves have union fittings.

Before I drain down and find out I can't fit the new valves easily - what
should I expect. Will the old union fittings remove easily from the rads,
and what tool is needed?

Will the new 15mm tails have the same screw fitting (into the rad) as the
old union types.

Thanks for your help.

--
Tony Collins