also please take care Paul that this isn't a thermostat in the traditional sense, rather it is an 'offset control' that will set a semi-permanent offset to the evohome set point
rather counter-intuitive to most; these are typically found in commercial buildings
if you want a simple room sensor you can also get a HCF82 without the adjustment wheel
I work for Resideo, posts are personal and my own views.
The way I think it works is it reports the temp back to the controller, but if you adjust the dial then that reported temp is offset.
E.g. If the room is at 20 degrees, and you set it to +2 then it only reports for the zone. So when the zone thinks it's at 20 it is really 22.
I only use it as a remote sensor in a room where the hr92s struggle. I don't use the dial.
Indeed, the HCW82 will 'offset' the setpoint temperature. So if the zone it is located in is 'scheduled' to 20 degrees and the HCW82 is set to +3 it will be +3 degrees on the evohome setpoint (i.e. 23 degrees). When the evohome Controller changes scheduled setpoint to say 16 degrees and the HCW82 was left at +3 it would actually control the room temperature at 19 degrees.
And I'm pretty sure the offset is purely local to the sensor. It isn't communicated back to the controller.