This brief tutorial will help you to Understand your Thermostat. Espically when it comes to Furnace Installations.
So what is a thermostat. T-stats (thermostat for short) are used in a variety of applications, In fact your cooking appliance most likely has a thermostat, so does your car. The t-stat were going to be talking about is the one on the wall in your home.
What does it do? Basically a thermostat is a switch. Just like a light switch when we want to turn something on (other then our spouse) , we just flip the switch on the wall up.
The thermostat is exactly the same principle , but it does the job without human interaction.
How does the t-stat sense temperatures?
Good question . The old style had a piece of metal in it that expanded or contracted when heated or cooled, when the metal was heated it expanded enough to flip the switch, then when it cooled sufficiently it flipped the switch the other way.
The new electronic t-stats have sensors that will change an electric property and send a single to flip the switch on or off.
Here is a basic and simple wiring diagram of a thermostat , and some explanation
So here is the deal……
R = Color red , and Power coming from the transformer on the Furnace
W = Color White , and this is the wire that send 24volts back to the furnace when the t-stat calls for heat. That 24volts starts the heating cycle
G = Green in Color (see a pattern) , this is used to manually start the fan in the furnace (most of the time)
Y = Yellow for color, and this will send 24 volts back to the furnace to start the AC cycle (if you have ac, if not you dont have ac you dont use this terminal
x (sometimes B and sometimes other colors) = usually black or blue in color, this is the common, or ground side of the transformer in the furnace.
Not all thermostats are the same , and many of them will have different parameters that the manufacturer would like you to adhere to. Those instructions are very important. READ THEM CAREFULLY BEFORE YOU DO YOU OWN THERMOSTAT INSTALL. If you have any questions you can always email me and I will try to help.
Here is another fine resource for thermostat wiring , Probably the most comprehensive i have ever seen . So if your stuck or have a more complicated system try this link
Hope this all helps with your furnace install – If you looking for a full set of written instructions look at my home page where you will find The Ultimate Furnace Installation Instructions
Regards Tony
