Has Anyone Used A Drain Easy Plumbing Accessory

[raybush]

I've got to change a leaky radiator valve and radiator due to it's age and the fact that I cannot re-pack or tighten the nut under the plastic cap.
I do attempt a bit of DIY plumbing ,changing rads etc and thought for this job I would try and use a Drain Easy Kit that consists of two rubber bungs that push into (on my OPEN VENTED system) the feed from the expansion tank that tops the system up and the overflow pipe.
I have a very very old hard to get at drain valve that I did not want to disturb just in case its seized ,or the valve seat has perished. I'm aware that you can drain down from the lowest radiator by turning the rad off ,draining it and then attach a suitable fixing and hose pipe onto one of the drain valves and turning it back on .My fear is that draining down may give an air lock ,I've done work on the upper floor rads and have just drained down the upper floor ,re-filled and bled the system with no bother. As I said the system is Open Vented and runs the Central heating and provides hot water to a tank .
If I can use the Easy Drain safely it could save a lot of work ,plus I hope that I've explained every thing ok ,as i'm not a plumber just a DIY-er.
Thanks

[The Builder]

I don't know the kit you refer to Ray. From your description, I don't think it would help because the rad and system would still contain water.

You really do need to drain the system in order to replace a rad valve.
Or ........... something I've used many times is a freezing kit. You would need to get at a length of pipe on both ends of the rad, and freeze it. That will give you half an hour or so to do the job without draining.

Once the flow & returns are frozen, you just have to drain off the water in that particular rad.

[Ryzen]

Yes a bung in the feed pipe within the FE tank will create a vacuum within the pipework..generally enough to enable valves etc to be swapped.You will still get seepage so be prepared.It will help if you shut off all upper valves.These bungs wont work if you intend to solder any fittings as the water seepage will cool the joint..unless you use oxy A or maybe Mapp gas.In this case you will need to do as TB says or drain down.

[raybush]

I may try a freezing kit.
I have about 8" of pipework from the floor to the bottom nut on the rad valve ,not sure if that is enough pipework for a freezing kit to work if it did i'd firstly freeze the rad tail that has the leaky rad valve and quickly drain the rad and hopefully change the valve using t same nut and olive and then ensure it's off ,I can the freeze the other side and change that one ........that's as long as the kit works.

[TWR]

As the Builder, 30min before it thaws, what if things don't go your way and you have complication? I would drain the system.