Many modern homes will have TRVs – Thermostatic Radiator Valves – attached to most of the radiators on the opposite side from the lockshield valves. A TRV should always be fitted to the inlet on the radiator and the LSV to the outlet.Click to see full answer. In this manner, which side of the radiator is the flow?Normally (but not necessarily!) the flow is on the left as you look at the rad.Also Know, where do you put a thermostatic radiator valve? Place the head on top of the valve, tighten the clamp and turn to set the temperature. Thermostatic valves can be fitted on any radiator, except the room where the main thermostat is located. Regarding this, does it matter which side of a radiator the TRV goes? Answer from Steve Harris, technical services engineer at Wavin: The vast majority of new TRV’s are bidirectional and can be fitted to either the flow or return, but it is always good practice to fit them to the flow side.Can you put thermostatic valves on all radiators?You should have thermostatic radiator valves (TRVs) on all radiators but not in the same area as a wall thermostat, it is possible that this room may never get warm enough to turn the boiler off via the wall thermostat if the temperature in this area is being controlled independently by a TRV.