How do you verify that a battery-powered digital thermostat is working like it should? From what I've read, it seems that it is supposed to electrically bridge the connection between R wire and the W wire, when it turns on heating. I detached a thermostat from the HVAC system and tested the connection between the two terminals using a multimeter *when the room temperature was well below the heating set-point*; the contacts on the thermostat corresponding to the R & W wires didn't seem to allow current to flow through. Given that it's an electronic device and may not respond to the small DC voltage from the multimeter the same way it may to 24 VAC, I can't tell whether the thermostat is good or bad.
Any ideas?