Help with stuck lockshield valve please

[mjgreen81]

Hi all,

I am trying to remove a radiator and I can't seem to close the lockshield valve as it is seized. I have already snapped off the flat bit at the top, but fortunately I still have enough of the spindle I can grab hold of with pliers, but it sill won't budge.

I've tried some Plus Gas dismantling spray and I have also loosened the gland nut but this didn't help. In fact I could totally remove the the gland nut without any leaking. Is that normal?!

Any advice appreciated, I would definitely prefer not to drain down the system if possible (it's a ground floor radiator unfortunately).

Thank you

 

[mjgreen81]

 

[jj4091]

Post in thread 'How to remove a TRV/ Lockshield valve without bleeding whole system'

Yesterday at 10:17 AM

I got the carpet washer ready, I knew under the carpet there were quarry tiles, did the job as fast as I could and water did not spread over on foot, and was quickly sucked up with carpet washer, as @Harry Bloomfield says, if air can not enter only lose water until pressure drops to zero. This was late mothers house, with a sealed system.

A fluid is incompressible, and cannot be 'stretched'. A gas (air) can be compressed, or 'stretched' - which means if you prevent air getting in, or make sure there is no air already in the water column, the water in the column cannot escape.

• Harry Bloomfield

 

[CountryFan]

Hard to tell exactly, but appears to be closed already?

 

[mjgreen81]

Hard to tell exactly, but appears to be closed already?

The radiator definitely gets hot if I open the valve at the other end.

I've also tried turning both ways just in case it helps free it up, but no luck unfortunately

 

[terryplumb]

Is the system sealed/ pressurised ,or fed from an F&E cistern in the loft ?

 

[mjgreen81]

Is the system sealed/ pressurised ,or fed from an F&E cistern in the loft ?

It's a fairly modern (the tank was replaced a couple of years ago - although the boiler is old) sealed and pressurised system.

 

[terryplumb]

You need to fit a new lock shield ,which is possible to do without fully draining the system. Close the other valve and drain the rad,after a while the water should cease to flow from the valve,and you can quickly swap the valve for a new one.

 

[mjgreen81]

You need to fit a new lock shield ,which is possible to do without fully draining the system. Close the other valve and drain the rad,after a while the water should cease to flow from the valve,and you can quickly swap the valve for a new one.

Thank you. I've been reading about this method and didn't realise it was possible without fully draining the system.

Just a couple of questions....

1.) Would it best to remove the pressure from the system in a controlled manner first? E.g. by bleeding some water from another radiator somewhere in the system first until it is no longer under pressure?

2.) Do I need to shut any valves etc on the cylinder first before attempting this?

 

[terryplumb]

Don't touch any other radiator. Use the air bleed valve on the radiator in question to reduce pressure a little before draining that rad.
Is the cylinder you refer to an unvented cylinder ?

 

[mjgreen81]

Don't touch any other radiator. Use the air bleed valve on the radiator in question to reduce pressure a little before draining that rad.
Is the cylinder you refer to an unvented cylinder ?

Yes it is unvented

 

[terryplumb]

You don't need to do anything regarding the cylinder or anything associated with it.

 

[mjgreen81]

You don't need to do anything regarding the cylinder or anything associated with it.

Thank you. I've watched a couple on videos now following your advice and it's giving me a bit more confidence to try this.

It's just scary opening up a 'live' system, but I guess that it's essentially basic physics and as long as air doesn't enter the system anywhere, it creates a vacuum and can't push the water out (I presume anyway!).

 

[terryplumb]

Correct ,it's the vacuum that holds the water from continually flowing.