Radiator thermostat letting heat through when set to off
One of my smart radiator thermostats has been causing a bit of an issue, where even when it is set to off, if the boiler is on (i.e. set to heat another room) some heat is still getting through to the 'off' radiator.
I don't think it's a calibration issue, as I've tried re-calibrating and also tried using one of my other smart radiator thermostats and the issue persists. This leads me to think its something going on with the radiator itself.
I've no idea where to start though as my radiator knowledge is next to zero (I'm amazed I was able to set this system up to be honest). So before I spend money on plumbers, has anyone else had this issue? Or does anyone think it may be something simple like 'tighten x up on the radiator'?
Thanks in advance.