I have a Water Heater ( 3 kW; 220 V; single phase) situated in one bathroom that has plumbing to service two bathrooms.
Currently it is connected to a local wall outlet (15 Amp) in Bathroom-1 with a local switch.
Is there an easy way to provide another remote switch in Bathroom-2 which can also control the Wall Outlet in Bathroom-1? I'm not sure of the operating logic yet; but perhaps a toggle with the last command operational, on or off, irrespective of whether issued locally or remotely. The idea being allowing the heater to be turned on ( or off) from Bathroom-2 as well.
Something like a relay? If the switch in Bathroom-2 can communicate wireless-ly to the Switch in Bathroom-1 that's even nicer. It eliminates the need to add wiring.