Wire the Honeywell Wi-Fi Smart Thermostat so that the C wire connects to the C terminal on its wall plate, the Y wire connects to the Y terminal and so on. Determine the letter assignment for each wire by referring to their connections on the old wall plate.
Before disconnecting the wires from the old wall plate, use the provided sticky tags to label each one according to the terminal it was connected to. If there is no wire leading to the C terminal but there is an extra, unused wire, or there is a wire connected to G but not to C, label it C. Note that, if there is no C wire, no G wire and no extra wire, the Honeywell Wi-Fi Smart Thermostat cannot work with that system.
Disconnect the wires from the old wall plate and detach it from the wall. Then, mount the Wi-Fi Smart Thermostat wall plate in its place. Afterward, connect each wire to its matching terminal. If you have both an R and RC wire, remove the jumper loop located under the R and RC terminals. If you had an extra wire but no C wire, connect the other end of the extra wire to the C terminal in the system's terminal block. On the other hand, if you had a G wire but no C wire, move the G wire to the C terminal in the terminal block, then add a jumper wire between the G and Y terminals.