I currently have a Robertshaw 300-208 thermostat running my Luxaire heat-pump and (some other brand) electric furnace as auxiliary heat.
I just bought the Honeywell RTH8500 thermostat to replace it.
There are two labels on the Robertshaw thermostat which do not correspond to any label referred by the installation manual for the Honeywell thermostat : "24V" and "24V(c)".
I've included pictures of the current wiring. Because some of the labels are hidden in the pictures, here's a top-to-bottom list:
W1 Y1 G R 24V 24V(c) O B
Here are the pictures:
Can anyone tell me which of my wires I should connect to which terminal on the Honeywell ?