Cold Radiator Fixed?

[AndyDavis]

I've got a double rad with a TRV at one end and a lock shield valve at the other other. The rad was stone cold but the pipes one either side were warm. A heating engineer closed the TRV and lock shield valve, then undid the nut connecting the TRV to the rad (I think he took off the lock shield valve as well but I'm not sure) and drained some of the water. Not all the water, about 2 litres I think. Connected it all up and the rad is working fine now, not piping hot everywhere but well enough to keep the room warm.

What has he done and is it a permanent fix?

 

[Armo74]

May have been a partial blockage or he may have freed off a stuck TRV valve pin.

 

[AndyDavis]

I thought it might have been a sticky trv to start with but he checked it and said it was fine, its fairly new.

What confused me was if he took off the nut at both (or even one) ends how come all the water in the rad didn't just spill out? I think he had to bleed it a bit before the water started coming out of the trv end.

What would have caused the partial blockage?

 

[gas_man_gaz]

could be airlocked if the rad is fitted on drops

 

[AndyDavis]

Pardon??