The R wire, which carries the 24 volt AC power from the HVAC system's transformer, can be connected to either the RC (cooling) or RH (heating) terminal, depending on your thermostat's configuration. In most cases, if you have a single transformer system, a jumper wire connects the RC and RH terminals, and you can connect the R wire to either one. For personalized guidance on wiring your thermostat, the Electricians Service Team is available to help with thermostat installations and wiring.