I assume a "wet" system (i.e. off the CH) would have a separate pump which would be heard when the thermostat calls for heat. Electric would be silent? I need to investigate a swollen wooden floor in a 3 year old build with UFH. Thanks diymostthings
wet would conventionally have a manifold, with flow stat and pump - and it's not uncommon to be able to hear it working with a ear pressed to the floor electric might have an adjacent spur to a wall stat, or a dedicated way in the CU - electric UFH wall stats tend to have a floor sensor fitted, as well as sensing air temp, so dropping the stat cover off may reveal consider the possibility of the floor being installed without a suitable expansion perimeter before you condemn the UFH
Wet has a manifold wet uf has a manifold, pump, blend valve, they rather noticeable. See if boiler fires up etc