Well R typically is power for heating and RC is power for cooling both come through the secondary side. C stands for common. Typically most people or any professional installer will use the blue wire for common. W is your heating relay. Now if you have the white wire connected to C that means you have 24 volts running to your heating side. C is only utilized when you have a non battery stat or have backup power to your stat.which means that's going to be your 24 volt power supply so if you have batteries it is optional if you don't it is required what I don't see that you have listed is G for your compressor which activate your cooling. Y for your fan and it typically kicks on about a minute before the heating actually is applied to the system to create static pressure in your ductwork or the same for your air conditioning side it may kick on momentarily before the compressor is energized so is you don't sludge the compressor with liquid refrigerant. If you only have two wires on the back of the thermostat hooked up that means it's more than likely just a slave or only runs in just heating or just cooling you need to provide more information because what you're saying doesn't make any sense.
