I need to replace an old rad with a new one. The existing one has two identical very old looking lockshield valves on either side. There is very limited pipework seen coming to the rad. I am fitting a TRV on one side but am not sure which is the flow and return. What is the best tip to tell which is which? I'm thinking turn the system on and see which pipe warms up first. Any other ideas?
Cheers
Cheers