Radiator valves

[Malamute01]

Hi there

Any advice appreciated on this one:

I'm looking to replace a small radiator and the two valves on an upstairs radiator that is on a combi boiler system.

Q1 Do I need to isolate the mains water first? The access to turn off the mains has rather unhelpfully been covered over by some laminate flooring! If I power off the boiler is that sufficient for it to stop drawing in cold water?

Q2 Will I need to drain all the radiators before removing the valves? I've seen a couple of videos on YouTube of a single radiator being drained down and the valves being removed. In one of the videos only a tiny amount of water came out of the pipe feeding into the bottom of the valve once the valve had been removed but huge amounts came out in another video I watched (and I would prefer to avoid risking the latter approach).

[Someone-Else]

1) A combi boiler heating is a closed loop. That means as it says, it is closed and the water that is in the heating system never changes (Unless it is let out or a pipe / valve is damaged) So, no, no need to turn the water off.

2) As it is a closed loop (under pressure) if you take a valve off you will let most of the water out. (Vaguely like opening a shaken can of pop)
What you should do is find the lowest drain off point, and drain the system down so there is no water in the radiator you wish to remove. Below is a picture of a drain off valve

beefburger.jpg (16.05 KiB) Viewed 283 times

When you have done what you need to do, you then fill the heating system back up (Re pressurise it) you do this by opening the valves for your boilers filling loop.

3) You said your main stopcock is under some laminate floor. I would suggest you make an access panel soon, very soon, because sods law says you will get a burst pipe/large leak one day when you least expect it, and there will be nothing you can do to stop it as the stop cock is..........that is when you will wish you had made an access panel to the stopcock.

[dewaltdisney]

A combi system is a sealed system. The incoming water is only turned on via the filling loop under the boiler. There are two taps, and they are only used to fill or top up the system when needed. To replace the valves on your radiator, you will only have to drain down the system water level below the radiator. You can also look at using a temporary pipe freezing kit https://www.toolstation.com/arctic-haye ... kit/p11221 if there is room on the feed pipes

DWD

[yartin]

https://www.youtube.com/watch?v=GnD9yoqEQrk

[Malamute01]

Thanks for the tips and advice. Really helpful!