creating a vacuum in trv/trv cap doesn't fit.

[liverpoolboy]

Hi-changing my TRV today guys, but come across a small problem. My new TRV is different to my old one and the plastic cap that came with it doesn't fit my old TRV. So WIll I have to drain down the system to replace it? I was hoping to create a paretial vacuum by bunging up the feed and vent and draining the rad, before obviously changing the valve. As I cannot shut off the water and drain the rad first is this going to be a problem... or can i just turn off lockishield ?

when i have installed my new trv, i want to balance the rad properley, not just guess how many turns i turned the lockshield head! Anyone know where I can get a pair of rad thermometers, the clip type, for not too much money ?

thanks guys.

 

[Rico99]

Hi LB,

Just close the lockshield, counting the number of turns to close it and write this in pencil on the rad.

Disconnect the try form the rad and drain off. I use a cat litter trya with notches cut out for different pipe sizes / entries.

Open the trv over the tray, you should only get a minimal amount of watwr come out, but be prepared to clse the trv quickly in case the bungs have worked properly.
I got caught out on a job and soaked me & the room in sh***y black liquid, but I had undone the nut under the trv(doh!) so was a beeatch to reconnect.

Change the trv, reconnect to rad and reopen the lockshield the same number of turns as you wrote on the rad.

Anyway good luck and try not to panic if it goes a bit Pete Tong.

Rico