Jammed Lockshield Valve

[Brad22]

Hi,

Looking for some advice please.

Yesterday I took the radiator off in my daughters room to decorate and replaced it the same day. I attempted to open the lockshield valve with a spanner and it is jammed shut. I am weary of giving it too much pressure in case I end up breaking the valve and getting a shower!! could this happen with too much pressure???

If I need to replace the valve without water going everywhere is this a major task?? I had a new central heating system fitted about two years ago, its an unvented cylinder system if that makes any difference.

Thanks in advance for your assistance.

Brad

 

[JohnD]

If it is unvented, you can open ONE point without a flood (because there is no secondary point that air can get in to, to displace the water. A bit like holding your thumb over one end of a hosepipe, water will not flow out until you take your thumb off.

Close the rad valves at both ends of the rad.

Loosen the nut on the radiator side of the faulty valve, and catch the dribbles in a paint-roller tray or similar. Have an assistant with a bucket just in case. the water should stop quite soon. When it stops, finish taking off that nut, then the compression nut that holds the valve onto the pipe, replace with new one, do up.

Things that may happen:

The new valve may not fit the old tail. unscrew it with a spanner of hex key (depending on type) and screw in the the tail you received with the new valve, with some PTFE tape.

The new valve may not fit the old compression nut on the copper pipe, or, the olive might be in the wrong place. In either case you will have to remove the olive. Sometimes they are loose enough to pull off with pliers (tale care not to damage the pipe) or you can saw part through them with a small hacksaw (do not damage the pipe) before twisting them off.

If the copper pipe comes through a wooden floor it will probably have some free movement on it. If it comes through a concrete floor it can be tricky if the old and new valves are different sizes.

When finished, you will repressurise the system using the filling loop at teh boiler.