Wiring a Smart Thermostat
Wiring a Smart Thermostat
When installing a smart thermostat, there are some things to consider. The first is the hardware. What kind of heating/cooling equipment is located at the home? Is there central air and central heat? What voltage is the system? What voltage is the control system? Do you even have enough wires to get the job done?!
When replacing a dial-style thermometer in my own home, I thought it was going to be a piece of cake. I pulled the old hardware off, installed the connection plate, and then attached the display. My old thermostat used only three wires to control the heat and cooling system. My new thermostat told me that I needed more wires to get the job done. This meant sourcing and pulling new wire so that I could have five wires going between the thermostat and the furnace.
After connecting the correct colors to the furnace and attaching them to the thermostat base (note: C is Cyan, which is blue), the thermostat recognized what was needed, and I was soon in the 21st century of heating and cooling!
Another note: if you run into a problem and the solution is not apparent after examining the equipment and/or reading the instructions, the manufacturer’s website and help forums are a great place, too!
Note, in the above example, there are several wire spots that were not used. What do these wires mean? Let’s take a look at the different wire colors.
Yellow (Y): These wires connect to the compressor of your AC system.
Green (G): These wires connect to the fan of your furnace or air handler.
Orange (O): These wires will connect to an air source heat pump. A heat pump may look like a regular air conditioning unit, but it can work in both heating and cooling capacities.
Red (Rc and Rh): These wires are the hot side of the power. The Rc is for dual transformers, while Rh only connects to the heating system.
White (W): These wires connect to the heating system. If you have multiple heating stages in the HVAC system, there may be more than one white wire.
Cyan (C): These wires are the common, which is a return path for the electrical current, so the smart thermostat can be powered.