There are two basic types of wireless thermostats available. One installs in a typical wired fashion, and mounts permanently to the wall, and the other has a controlling unit which mounts to a central location, and has remote thermostats that can be moved from one room another. Both types can be controlled with a wireless remote, and installed in pretty much the same way. The only difference is that the remote sensor variety allows you to move the wireless sensors to the rooms where you want to control the temperature.
Step 1 - Remove the Old Thermostat
Begin by disconnecting power to the HVAC unit and thermostat. Next, pull the face of the old thermostat off the wall. Inspect the wiring to be sure that everything is in good working order. Allow the thermostat to dangle.
Step 2 - Remove the Existing Mounting Plate
Remove the existing mounting bracket or plate. This plate is used to give the thermostat a uniform mounting surface, and will be different from one thermostat to the next. Most mounting plates are held in place by two to four screws, which are easily accessed when the thermostat face is no longer blocking it.
Step 3 - Disconnect the Wiring
Beneath the mounting plate is the wiring box. The wires leading from the thermostat come this box, and then junction off to their various required locations. Disconnect the wires, but note which connectors they are attached to. In most thermostats, the connections for the wires are labeled with the first letter of the color of the wire. For instance, you may have red, white, and yellow wires, and their respective connection labels will be R, W, and Y. If the colors or connector labels do not match, be sure to make notes of which wire was used for what connector.
Step 4 - Connect the New Wires
Connect the wires of the wireless thermostat according to the manual instructions. Usually, you can simply reverse the disconnection process, but double check the directions to be safe. By now, you may be wondering why wires are being connected to a wireless thermostat. The fact is that the thermostat is basically the same device it has always been, and the wireless features comes into play because the thermostat can be adjusted using a remote control, or the wall mounted box will wirelessly connect to portable thermostats in other rooms.
Step 5 - Install the New Mounting Plate and Thermostat
Install the mounting plate that was included with your wireless thermostat. take care that you do not crimp or pinch the wires, and there are no bare wires exposed inside the wiring box. When the plate has been mounted, the new thermostat should snap snugly into place.
Step 6 - Test the Wireless Features
Using the remote, test out your new thermostat. First, set the temperature up to a high temp, and verify the heat works correctly, and then do the same for a low temp, to test the air conditioning ability. If your wireless thermostat includes portable sensors, move them to different room and test them out to make sure that they are transmitting the signal correctly. Test every room of the house, because it may be possible for some rooms to have no signal while others work fine. If this happens, you will likely have to move your wall-mounted controller to a new location.