Hi, recently had TRV fitted to l/room radiator by plumber. He also renewed lock shield valve on rh side too. We did call him back following day because LSV was leaking a little bit. Once plumber left we put heating on for the first time since valves replaced but l/room rad does'nt heat up. It does slightly but not even warm. Even at different settings.Tried bleeding but its full. Pipe leading to TRV is hot but pipe leading from LSV is cold. Is the LSV the problem. Have called plumber back but not responding. Cheers