Radiator update to thermostat rad valve's

[AidanGee93]

Pls see pics...
Got 10mm copper flow and return pipes, have standard lockshield valves and want to replace to TRVs. Will the one in pic (Screwfix) work? I see it's 15mm but think it comes with a 10mm reducer for the copper pipe...

Also, if I drain my central heating system (as have a few of these to fit while renovating rooms) and don't plan to use central heating can I still shower and run hot water for bath/basin etc? It's a combi boiler and currently on the switch for hot water only, won't switch it to hot water and central heating...
Cheers, Aidan.

[Nickfromwales]

Hi. You’ll need a sealed and pressurised system for the combi to work for hot water.

 

Just buy cap end when you remove valves / rads, and fill the system back up to normal working pressure. 
 

You’ll heard few gurgles for a day or so where the system has to evacuate all the air out, maybe, and you’ll prob need to top up the pressure a little the next day. 
 

Then you can leave the rooms capped, decorate, and the do one more drain down and refill with all new valves done in a day.

 

Use a junior hacksaw to cut the pipe under the existing nuts, as the pipe where the olive is will be compressed, and if you remove just the olive and push that into a reducing set, it’ll leak. You need to be on to fresh clear pipe. 

[dpmiller]

looks like the original valves have 1/4 or 3/8 nuts on, so the nuts and olives will need removing regardless