The Basic Components of Your HVAC System


The majority of residential and commercial buildings have HVAC systems. They primarily function for cooling and heating but also ensure that indoor air contains adequate amounts of oxygen and doesn’t contain toxic gasses.

Energy efficiency ratings, such as SEER for air conditioners and HSPF or AFUE for furnaces, help compare equipment performance. Regular maintenance, upgrading to energy-efficient equipment, and improving insulation can help lower utility bills. Contact 24 Hour HVAC Company for professional help.

Thermostats are responsible for regulating temperature in your home and activating the rest of your system when it’s above or below the set point you’ve manually chosen. They are the portion of your system that you interact with most, which is why they are usually mounted on easy-to-access walls in your home. They also help ventilate by allowing hot or cold air to move into and out of the regulated spaces.

A traditional thermostat has two pieces of different metal bolted together to form what’s known as a bimetallic strip. This strip works as a bridge in an electrical circuit connected to your heating system. When the strip gets warm, it expands slightly. This causes it to bend a little and makes contact with an electronic switch, triggering the heating system to turn on.

When the room cools, the strip contracts. This makes contact with an electronic switch and turns off the heating system. The switch may make a slight click noise when it switches on or off.

Modern thermostats have electrical contacts that aren’t exposed to the elements and are held behind glass for protection. When the system is turned on, these contacts close to complete an electrical circuit. When the room gets too cold, the contacts open to stop the flow of electricity, causing the heating system to shut off.

Thermostats in newer homes are often smart, meaning they connect to your Wi-Fi network and can be operated from a smartphone or tablet. This allows homeowners to monitor their system remotely, detecting any issues before they become serious and making it easier to schedule repairs and maintenance visits. It can even detect if doors or windows are open when the HVAC system is operating, enabling owners to take preventative measures against carbon monoxide and other threats.

Combustion Chamber

The combustion chamber inside your furnace is where air from your home combines with fuel that’s burned by the burners to create heat. Older systems use a pilot light to ignite the flame, while newer ones have an electronic ignition system. Both will turn off your system if there isn’t enough flame to burn the gas. This prevents carbon monoxide poisoning in your house.

The design of the combustion chamber is critical to its function. A cylinder-shaped chamber has the advantage of being able to generate high levels of pressure without bending or deforming. This allows for the smallest possible surface area of the piston to be heated as it moves through the combustion process, which leads to more efficient combustion and less waste of energy.

A cylinder-shaped combustion chamber also gives it the ability to contain and release extensive volumes of gas while still maintaining a relatively low pressure level. This is a necessary condition for the combustion process to be efficient, as it ensures that a large proportion of the available fuel is burned in the shortest possible time.

As a result, the combustion chamber is designed to have an even temperature throughout its volume. This is accomplished by using a set of valves that open and close to control the flow of air into the chamber. In addition, a system of sensors and actuators are used to monitor the performance of the combustion chamber and to correct any abnormal conditions that might arise.

The combustion chamber is also designed to be durable. Over the course of a furnace’s lifespan, metal expands and contracts several times as it goes through the heating cycle. This can lead to cracks in the combustion chamber. These cracks could allow air from outside to mix with the burning fuel, resulting in carbon monoxide poisoning.

Air Handler

An air handler is a crucial component of your HVAC system. It regulates the flow of indoor air and maintains the temperature you set on your thermostat. It contains a blower, air filter and evaporator coils that help your home feel comfortable. The evaporator coils in an air handler contain low-pressure, low-temperature refrigerant gas that absorbs excess heat from indoor air. The blower then circulates this cooled air through your home via your duct system.

When your air conditioner is running, the air handler takes this cool air and transfers it through ducts to rooms that need heating or cooling. It also uses its blower to circulate fresh outdoor air into your home. This helps manage odors, control humidity and maintain a healthy, comfortable indoor environment.

You can find three different types of air handlers: packaged units, split systems and ductless units. Packaged units are all-in-one devices that include both a heat pump and an air conditioner. Split systems use an outdoor component, which is a condenser unit, and an indoor air handler that includes an evaporator coil. Ductless units have built-in blowers to move air throughout a space without the need for ductwork.

Air handlers come in a variety of sizes and designs. Smaller units, which are often located in the attic or basement, may only consist of an air filter, coil and blower. These simple terminal units are sometimes referred to as fan coil units or blower coils. Larger air handlers, which are used for commercial spaces or in larger homes, typically feature multiple electric heat strips that work similar to the heating elements in an electric oven or toaster.

Air handlers are also designed with various controls to manage how they operate. Some may have single-speed motors while others operate at multiple speeds to provide a more precise airflow. Some even have variable-speed motors to reduce energy consumption by operating at only the necessary levels of speed.

Return Plenum

A return plenum connects your air conditioning system’s ductwork to the return inlet, allowing cool or warm air to travel back into the system for another cycle of heating or cooling. This second stop for the air is crucial in ensuring ample indoor airflow and proper circulation throughout your home or business. It also helps reduce noise levels, as well as improves indoor air quality by removing pollutants and contaminants before they reach your rooms or spaces.

A plenum box is a large, rectangular-shaped enclosure inside your ductwork that holds an air filter to keep the interior of the ductwork clean. It is usually located at a low point in your ductwork, such as the return vent or air handler, to keep dust and debris from collecting in the ductwork.

There are two types of plenum boxes, the system supply plenum and the system return plenum. The system supply plenum is used to distribute air to your entire building or home, and it can be either above or below the AHU or AC coil in an up-flow configuration. The system return plenum is used to collect air from the system’s return vents and redistribute it.

Since your HVAC system is constantly producing heated or cooled air, the return plenum is responsible for efficiently pulling that conditioned air from each room in your home or office and returning it to your ductwork. The return ducts are connected to the return plenum and fitted with an air filter to ensure that conditioned air is only being sucked back into your HVAC system.

Proper plenum installation is essential for optimal airflow, energy efficiency, and contamination prevention. Non-professional installation or maintenance can lead to air leaks and temperature inconsistencies. If you are planning on installing a new HVAC system or replacing your existing ducts, consult with a qualified HVAC contractor to ensure proper plenum installation.

Air Filter

The air filter acts as a catch-all for particles that would otherwise reach the working components of your HVAC system. If they were to make it to the blower, coils and ductwork, they could clog them or cause damage. The air filter prevents this by catching a wide variety of pollutants, including pet dander, dust mites, mold spores and cigarette smoke.

A dirty air filter restricts the flow of air, causing your system to work harder and consuming more energy in doing so. It can also cause the system to wear out more quickly and require more frequent maintenance. A clean filter, on the other hand, improves energy efficiency and extends the lifespan of your system.

Different types of air filters exist, and the one you choose depends on the size of your vents, the level of filtration you need and whether anyone in your household suffers from allergies or respiratory issues. Fiberglass filters are disposable and the least expensive option, but they do not prevent the smallest contaminant particles from entering your home and can easily become clogged with debris from circulating air. They typically have a MERV rating between 1 and 4.

Electrostatic filters, which are reusable and more expensive, attract dust and other contaminants to their surfaces with an electrical charge and have a MERV rating between 6 and 10. High-efficiency particulate air (HEPA) filters offer the highest levels of filtration and can prevent cigarette smoke, bacteria, viruses and other toxins from passing into your home’s vents. However, they are more difficult to install and require modifications from a professional for compatibility with your HVAC system. The EPA recommends speaking to a knowledgeable associate at your local home improvement store or HVAC company to determine the best type of filter for your home.