Radiators not heating up

[PharmerGiles]

Hi,
The living room and bedroom no 2 radiators will not heat up in our apartment. There is hot water in the pipe up until the lock shield valve. There is a very slight warmth along the top of the drain valve section between the lockshield valve and the radiator but no real heat in the radiator itself. I tried bleeding the radiator and water came out straight away so it doesn't seem to be airlocked. There is a screw on the underside of the drain valve which i opened and again water came out straight away. Unfortunately when i tried to close it, it just kept going round and round and leaking so I've had to isolate the radiator at both ends. I suspect the drain valve is blocked/broken and preventing hot water entering the radiator. Does this happen with these types of valves or is it a case of the system not being balanced properly. I think the 2 cold rads are the last 2 on the system.
The lock shield valve is a myson matchmate and is on the flow side of the radiator.
Thanks

 

[terryplumb]

If both rad valves are closed ,you can unscrew the drain cocks spindle completely ,and remove it for inspection , particularly it's thread which may be stripped if it will not screw fully closed.
The drain cock doesn't prevent water entering the rad ,and it's very unusual for it to be blocked. If you turn off all working radiators by their TRV's ( if fitted) ,do the problem rads heat up ? You will of course need to sort out the drain cock on one of them first.

 

[Wayners]

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Other side of radiator has a thermostatic valve? Is so.
Pin sticks in so always off.
Look up how to fix a stuck thermostatic valve.