How to connect two inputs to one output for a mains connection
simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. (a) Typical 2-way switching as used on stairways. (b) OR switching.


If you want either room to be able to switch on or off then use (a).
If you want the heater to be on if either or both rooms require it then use (b).


If you want to switch the input to the digital system then:







simulate this circuit

Figure 2. Switching an input for a digital controller.