Thermostat Wiring

 But this is a, an HBAC 24 volt electrical training board. So this is the entire 24 volt electrical system for a heat pump. So for the first episode, we're gonna start, we with the brain. We're gonna start with. Our thermostat. Now, this is a very run of the mill basic thermostat. Thermostats come in all shapes and sizes, right?

Uh, you have learning thermostats, you have programmable thermostats that can do various things. Some connect to wifi, some do not. This is basic. You tell it what you want it to do, and it will flip the switches and control the power and send it to the components necessary to make. What you want to happen happen.

But how does it do that? You have your controls on the front, whether you, your, your setting for fan is in auto or on, uh, this is a heat pump again, thermostat. So I have a cool function. I have an off, I have a heat and I have an emergency heat. Now, each one of these. We'll send power to different components based on what I have it set on.

But for right now, we have it set to cool. Why? Because it's 48 degrees in here, but that's okay. We're in the cold snap. But for the sake of the training purpose, we're gonna leave it set. To cool. We're gonna auto and we're gonna adjust the thermostat down somewhere below 48 degrees, and the thermostat is gonna act like a switch to turn all of the components on necessary to get to that 48 degrees.

What did I do? There we go. I accidentally turned it off when I flipped the uh, or when I took the cover off, so there we go. All right. Now you can see in here the different color wires. Each one of these wires controls a separate component on this system. What's important to know about a thermostat is that each one of these wires have a distinct purpose.

The red wire right here. That is your 24 volt wire. That is the wire necessary to send power to all of the other 24 volt electrical components. Alright, the blue wire right here is your common wire or your C wire. Because this is alternating current, you need the C wire to close the circuit. And in this instance, this C wire is powering the thermostat.

You see, I do not have batteries in here. So the C wire is important for that function. Yellow wire right here controls your compressor or your condenser. Green wire right there controls your indoor fan, right? That is your evaporator fan motor. You have a white wire tucked in right here that represents your electric heat and then you cannot see it, but there is a black wire in there.

Uh, and that controls our reversing valve needed to power the reversing valve solenoid, which is controlled in AC mode on this particular heat pump. So when a thermostat is set to cool, which this one is, the red 24 volt wire will then send a signal all the way out to the defrost control board telling the contactor to kick in and turn on your condenser.

Which is the yellow wire. It will then tell your indoor fan the green wire that it needs power to control the fan on the inside. So these are the things that are being powered when I'm in AC mode. So for the sake of this board and the training purposes, we have our evaporator fan, our blower motor is running.

Because the green wire is getting power because it's in cool. We also have our condenser, our compressor represented by the yellow wire, so it has power contactor pulled in, which made this connection, which turns on our condensing. This is our condensing fan. This is set up. This is a Goodman Defrost control board.

So our reversing valve also has power. This is not lit up quite a, uh, very much because this is a 24 volt cycle, so you're not getting full current to this bulb. That's why it's not, this is a 24 volt bulb, so it's much brighter, but this represents that the reversing valve is getting power. So the thermostat is just a switch.

It is literally like a light switch in your home. Flip it down. You have no power. Flip it up. The power is connected and it sends the signal to the light to tell it to come on. Your thermostat does the same thing based on the settings you put in. If you tell it you want ac, it will send power to the components that control AC if you send it or if you want heat.

And you put it in the heat sector, it will send power to all the components that control the heat side, and that is how a thermostat works.