Thermostatic radiator valves

[Jfw82]

Does anyone know how easy it is to change radiators over to thermostatic radiator valves? Has an extension done and all new radiators have TRVs which has made us realise how useful it would to to have them on the older radiators.

It's not so difficult depending on the length of the tails and the age of the fittings. I didn't drain the system on mine. I turned off the tail stock and the adjustable valve. Cracked open the compression on the tailstock and drained the rad into a pot with a towel to catch any splashes ( small pot emptied into a bucket). Just in case I tapped a rubbish bag to the wall and rolled the edge up with some masking tape to form a bund. Once the rad was empty I separated the joint between the rad and the valve. Then I prepared the new trv, next I undid the joint on the vavle to the pipe whist keeping pressure on it, then quickly pulled the old one off and poped the new one on. This was on a gravity system, on a pressured system bleed off the pressure first. I also changed the rads at the same time as they were old.

I should add that I used bungs in the header tank and vent, although the header tank bung had a hex internal a didn't seal well.