TBZ500Connect the wires according to the HVAC system Step

R vs RC and RH Connections: Single Transformer HVAC Systems. Typical modern central HVAC installations have a integrated heating and cooling system with a single 24VAC transformer. For these systems, there is only one 24VAC “R” wire and it can connect to either the RC or RH terminal on the thermostat. The thermostat is supplied with an RC-RH jumper installed. Do not remove the jumper for common transformer HVAC systems.