Single radiator not working

Chris R · 2010-12-19T09:24:17+00:00

I have one radiator that has gone completely cold. Rest of system is functioning normally, bled it an no airlocks, valve pin in TRV moves freely. What is my problem likely to be and how do I diagnose it? I can only think of a frozen pipe (seems unlikely in a house that has constantly been heated and in a room with two rads) or a stuck valve at a level below the pin.Chris R