Changing radiator valves in pressurised system

[janieJones123]

Hi all.

I am wanting to swap out some old radiator valves for some new TRV ones. I currently have the radiator off the wall, and the current valves closed off. I just want to run through the steps that I need to take in order to be able to remove the old valves, put on the new ones, and hook the rad up.


I have a Worcester 28i Junior gas combi boiler, and this is my setup.


1. Firstly, I need to switch off the central heating, by flicking the white switch.


2. Then I need to shut off the water by closing the yellow valve.

3. Then I need to drop the pressure completely by turning the black button on the top of the red cylinder until the needle on the boiler has dropped to zero.

4. Now I can go and replace the two radiator valves, and hook up the radiator, with the bleed valve on the radiator still closed. And open the new valves.

5. I now turn the water back on by reopening the yellow valve.


6. With someone at the radiator, they will open up the bleed valve, while I increase the pressure in the boiler using the white plastic nut on the underside of boiler.

7. Once the bleed valve starts to spit water and the rad is full, they will close it off, and I will increase the pressure to 1 bar.

8. Finally, I turn the central heating back on again.

Is there anything I'm missing or don't need to do here?

Thanks a lot!

 

[Garfeild]

The yellow valve is gas, you don’t need to touch it, or the red expansion vessel.
Just open one of the rad valves you have removed the radiator from, slowly into a bucket, once the water stops, change the valves, you may get a little water spillage, but nothing major, the rest is as you described it rad vent and fill to 1 bar.

 

[janieJones123]

Thanks @Garfeild

Ah I see, so I can just depressurise the system using one of the current old valves.

So its just:
1. Turn off central heating
2. Open current valve until water stops
3. Make the switcheroo and hook up rad, opening new valves up
4. Open bleed valve and increase pressure under boiler
5. Turn central heating back on

The radiator is upstairs, so I take it doing this will just drop the pressure enough to change the valves over, rather than draining the entire system through the whole house?

 

[Garfeild]

Yes that’s about it, easy enough keep an eye on your connections as you fill the system and pressure rises, may be a good idea to find the drain off point on the ground floor in case of any problems as you will have the radiator fitted and will not be able use the valves to drain off as you did before