To the average homeowner, HVAC systems are mysterious, complex devices that somehow keep homes warm during the winter and cool during the summer. The truth is that central HVAC systems aren't that complicated, especially when you take the time to learn how they work.
Having a basic understanding of how your HVAC system works can give you the upper hand when it comes to repairs and service. The following offers a detailed explanation of how your HVAC system heats and cools your home.
Common HVAC Components
Like a well-trained orchestra, your HVAC system consists of numerous separate parts that are designed to work together in harmony. On a central HVAC system, these components split between the outdoor cabinet and the indoor air handler.
The outdoor cabinet, located just outside of your home, contains the compressor, condenser coil, and condenser fan. The fan pulls air from the bottom of the cabinet and expels heat released from the condenser coil. Several refrigerant lines connect the outdoor cabinet to the indoor air handler.
The air handler contains the blower fan, which pulls air through a return air duct. The air passes through the evaporator coil before making its way through your home's ductwork. This is how your HVAC system distributes heated or cooled air throughout your home. On most HVAC systems, the air handler also shares space with a gas, oil, or electric furnace.
The thermostat regulates the heating, cooling, and ventilation for your home. While most HVAC systems come with relatively simple thermostats, you can easily upgrade these devices to programmable versions. Programmable thermostats offer more settings and finer controls for heating and cooling.
Setting your thermostat to fan or ventilation mode allows the blower fan to run continuously without heating or cooling your home. A filter located inside the return air vent collects dust and contaminants from the incoming air before it travels further through the air handler and into the ducts.
Most HVAC systems come equipped with blower fans that operate at only one pre-set speed. HVAC systems fitted with variable-speed blower fans can vary the flow of air to reduce noise and enhance overall comfort.
Air conditioners don't actually cool your home's indoor air. Instead, they use refrigeration to remove, transport, and expel latent heat from indoor air, causing temperatures to decrease in return gradually. Refrigerant inside the evaporator coil pulls latent heat from the passing air, making the air that eventually enters the ductwork cooler.
Meanwhile, the refrigerant travels through the compressor, where it forces the refrigerant into a hot, high-pressure vapor. The vapor then pumps through the condenser coil. Airflow from the condenser fan releases the latent heat into the atmosphere, transforming the hot vapor into a warm liquid.
The refrigerant then moves through an expansion valve that rapidly converts the warm liquid into a cool vapor. At this point, the refrigerant is ready to move through the evaporator coil, where the process repeats.
The air conditioning process also extracts moisture from indoor air. The resulting condensate captures in a drip tray located underneath the evaporator coil, where it collects until drains directly outdoors or through an indoor drain.
Setting your thermostat to heat or heating mode ignites the burners on a gas or oil-fired furnace or activates the heating elements on an electric furnace. The resulting heat is captured by passing air and carried through the duct system.
On gas and oil-fired furnaces, a metal heat exchanger will contain combustion gases produced by burning fuel. As air passes through the heat exchanger, the airflow picks up the heat and carries it toward the ducts. Meanwhile, the gases expell through a separate vent leading outdoors.
If you're using a heat pump instead of a furnace, your heat pump will work just like your air conditioner - except in reverse. Instead of moving latent heat out of your home, your heat pump will gather latent heat from outdoor air and bring it indoors.
Want to learn more about how your HVAC system works? Contact the professionals at Climate Heating & Cooling today.