How Does a Central AC Unit Work?

More and more people have stopped using split AC units and are switching to a central system instead. Besides being quieter, a central AC unit is also able to distribute cold air evenly throughout the house. However, before you decide to install a central AC system, it is best to know how the system works first.

The Components

First, you need to know the basic components of a central AC system. Here they are:

1. Thermostat

The thermostat is the device that detects the air temperature. You can also set it to a specific temperature that you consider ideal. When the indoor air passes your ideal temperature, the thermostat will signal the AC to start automatically.

2. Registers

Registers are the grills that work as doors for the indoor air. Each room of your house will have at least two registers. The supply register is located near the top of the wall, close to the ceiling. The return register is mounted down on the floor.

3. Ducts

Ducts allow the air to flow in and out of the room. This piping system connects registers to an air handler. Just like with registers, there are two kinds of ducts. Supply ducts are for delivering chilled air into the room, while the return ducts send the warm indoor air back to the air handler to cool it.

4. Air Handler

This unit regulates air circulation. It sucks out the warm indoor air, pushes it to the evaporator, and blows the chilled air back into the room.

5. Evaporator

Mounted on the top of the air handler, an evaporator unit works to take out of the heat from the indoor air.

6. Condenser

As the only component located outside the house, the condenser works to disperse the heat out of the house.

How the Central AC Unit System Runs

When the room temperature hits the level you set, the thermostat will signal the AC system to start. The air handler unit will suck indoor air from the return register through the return ducts. A blower inside the air handler will push the air into the evaporator.

The evaporator will then strip the heat out of the air using the liquid refrigerant. This process causes the air to turn cold. Then, the air handler will push the chilled air through the supply duct. That chilled air will end up entering the room via the supply register. The air that has been in the room for a while will flow into the return duct to restart the whole process.

Now let’s get back to the evaporator. As the refrigerant absorbs the heat from the air, it will turn into gas. Then, the hot refrigerant gas flows to the condenser unit outside, which disperses heat to the outdoor environment. With no heat to carry, the refrigerant will turn back into a liquid and flow back to the evaporator to repeat the cycle.

Knowing how central AC works may help you decide whether you should install one or not. And if you already use one, a better understanding of the system might help you see the importance of regular maintenance and proper treatment. Still, always hire a licensed HVAC contractor to install or service your central AC.

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