CH drain valve won't shut

[phloaw]

Today I drained my CH/HW. This is a standard vented, pumped S plan with two electric valves, and I'm in UK.

I was lucky enough to have a drain valve underneath ground floor, relatively accessible, see pics:

However, upon refilling the system, I found out that that valve will rotate endlessly, and won't guarantee proper isolation: it's stripped.



I was thinking to add an isolating (aka service) valve past the old one, i.e., along the pipe in the bottom part of the images.

Something like this:

Do you think that will work? Or is there a risk that the old valve will leak when the new one is shut? Do you foresee any other possible problem?

Any feedback welcome!

Thanks!

 

[sircerebus666]

You would be much better off fitting a drain cock , that way you can attach a hose pipe to it next time you need to drain down your system

Or that isolation valve then a drain cock , that way you can be doubly sure it won't leak

 

[phloaw]

You would be much better off fitting a drain cock , that way you can attach a hose pipe to it next time you need to drain down your system

Or that isolation valve then a drain cock , that way you can be doubly sure it won't leak

The problem is I have no idea where the pipe past the broken valve ends. It goes somewhere to the bottom part of second picture, which I cannot see.

I drained the system hoping it ends in the waste piping, but now you are making me wonder.

 

[sircerebus666]

The problem is I have no idea where the pipe past the broken valve ends. It goes somewhere to the bottom part of second picture, which I cannot see.

I drained the system hoping it ends in the waste piping, but now you are making me wonder.

Ah ok missed that , then just that isolation valve will be fine, you may get away with removing the old one and putting the isolation valve in its place

 

[phloaw]

Ah ok missed that , then just that isolation valve will be fine, you may get away with removing the old one and putting the isolation valve in its place

Thanks, since the old valve is in an awkward position, I just left it and placed the new service valve past it, hope that will be fine.
But now I have bigger problems: upon refilling, no radiator will bleed, the system looks empty.
I suspect a blocked feed, expect a separate post!

 

[Hugh Jaleak]

Whilst system is empty, ditch the service valve and fit a full bore lever valve, chances are that service valve will leak next time you try and use it, and that's if you can shift it again. https://www.screwfix.com/p/lever-ball-valve-red-15mm/67744 The existing valve looks rather like a gas cock, which will be 1/4 turn on to off anyway. Not sure its entirely suitable for use with water.

As for cold feed, try a magnet on the pipework, if it attracts, that's where your blockage is. Only solution to that, cut pipework out and replace. Ideally clean the system then before adding inhibitor.