If there is a heat pump outside a house, then there is likely an air handler somewhere inside. Air handlers are best described as air distribution systems and are most often found in basements, attics or dedicated closets. This system looks very similar to a gas furnace — so much, in fact, that many people mistake it for one. This guide explains the components of this system, how it works and what size is best for your home or business, then shares some handy maintenance tips.
What Is an Air Handler?
Think of an air handler as your home's lungs. Air handlers don't heat or cool the air, but together with heating and cooling equipment, they handle the flow of air that keeps your house clean and comfortable all year round. The cabinet of the air handler contains some indoor components of the HVAC system, as well as some additional items that serve to improve ventilation and indoor air quality, such as electronic air filters, ultraviolet (UV) light and dehumidifiers.
Components and Parts of an Air Handler
An air handler generally contains the following components: 1. Blower motor. This motor pushes air through your ductwork, allowing it to circulate throughout your house. Various types of motors are available in air handlers, including single- and multi-speed motors, which run at fixed revolutions per minute (RPMs) and are designed to move a consistent amount of cubic feet of air per minute. Variable speed motors, on the other hand, adjust their output based on the conditions they monitor, thereby maximizing efficiency. A variable speed motor is also sometimes referred to as an Electronically Commutated Motor (ECM). 2. Plenum connectors. Plenum connectors are boxes that connect your supply and return ducts to your air handler. Supply ducts carry the cooled or heated air to vents, which are also known as terminal registers, in each of your home's rooms after the air has traveled through your filter and air handler. Return ducts are responsible for bringing unconditioned air from each of the rooms back into your system, where it will then be filtered and conditioned once more. 3. Air filter. When unconditioned air is brought into the air handler, it passes through a filter. This is because this air can contain dirt, debris and other particulates that could cause damage to internal components of the air handler. The filter serves to protect these components by capturing any incoming particulates. 4. Evaporator coil. The evaporator coil enables heat energy to be removed from or added to the indoor air. In an instance where the air is being cooled, refrigerant, which is located in the air conditioning unit outside, is pumped in in the form of a high-pressure, high-temperature gas, where a valve then converts the refrigerant into a low-pressure, low-temperature gas. This gas is then pumped into the evaporator coils, and when air passes around these coils, heat energy transfers from the air to the refrigerant, thereby cooling the air. This cooled air then continues on out through the supply ducts. The refrigerant in the coils, which now contains heat energy, is then pumped back out to the outside unit again, where the cycle continues. 5. Electric heat strips. Some air handlers are also equipped with electric heat strips, which use electricity to provide additional warmth when needed. They can be used with both AC-only systems as well as with heat pumps when it gets too cold. It is important to note that the components of air handlers vary from region to region and from manufacturer to manufacturer. The parts we've described above are found in typical air conditioner/heat pump setups.How Does an Air Handler Work?
Your air handler circulates conditioned, filtered air through your home in four basic steps. In this section, we'll explain each step that an air handler goes through to circulate air through your home. They are as follows: 1. The air handler pulls the air in. Return air, which is air coming back through the return vents, is pulled into the air handler, where it is then filtered. 2. The air is filtered. Air traveling through ductwork can carry contaminants that can damage the internal components of the air handler, as well as cause those in the house to become sick. This is why the air first passes through an air filter, where airborne contaminants like dirt, hair and pet dander are captured, allowing only clean air to pass through to the coils. Change this filter frequently to ensure that the air stays as clean as possible and can flow more smoothly. You should change the filter at least once a year or, if you have pets, allergies or asthma, even more frequently. Consult your owner's manual regarding the recommended frequency for your unit. 3. The air passes through the coils. Once the filter has cleaned the air, it then passes through the evaporator coils, where it is heated or cooled. In either case, the refrigerant is pumped into the coils from the outside unit. If the air is being cooled, the refrigerant will be a high-pressure, high-temperature gas, and a valve will convert it into a low-pressure, low-temperature gas, which then goes into the evaporator coils. When the air passes between these coils, the air is cooled. The refrigerant then makes its way back outside, where the cycle starts over. 4. The air is blown out: Once the air has been conditioned, the blower pushes the air through the supply ducts until it reaches the vents throughout the house, delivering conditioned, filtered air to your living areas.
What Size Air Handler Do I Need?
An air handler's size is directly related to the size of the condensing unit. To determine the size of the air handler that your application requires, follow the steps below: 1. Determine the required size of your condenser unit. Call an engineer and have them perform a load calculation for your home. This will determine the tons per square feet that the condenser must be capable of handling. Typically, one ton is required for every 500 square feet. 2. Determine the required size of your air handler. Your air handler size depends on the size of the condenser unit. So if the air condenser must be 4 tons, then the air handler must be 4 tons, too. The air handler can be larger than the condenser unit by up to 1 ton, but the better you can match the sizes, the better the performance will be. 3. Make sure you have the electrical capacity. Some air handlers require more energy than others. Find out the energy requirements of your unit and confirm that your electrical setup is capable of supporting it. If you have insufficient capacity, then you have two choices: either redo your electrical connections or resize your air condenser and air handlers to the largest size that your current electrical connections can support. You can check the electrical capacity by viewing the circuit breaker panel. On the panel, look for the air handlers, and beside it should be its maximum rating. Compare this rating to the electrical requirements of your air handler, which you should be able to find in the air handler's manual.Air Handlers vs. Furnaces
As air handlers and furnaces are often mistaken for one another, it's not uncommon for people to wonder what the difference is. Luckily, this question has a straightforward answer. Let's start by discussing how the two systems are similar: • Exterior appearance. Air handlers look just like furnaces on the exterior. After all, they're both big, metal cabinets. This is why people often confuse the two. • Purpose. They both condition and circulate the air that travels through a house. Air handlers and furnaces differ in the following ways: • Heating components. Air handlers, unlike furnaces, lack burners, heat exchangers and other heating components found in furnaces. • Source of functioning. As air handlers do not contain burners to heat the air like furnaces do, this means they cannot run on propane or natural gas. They instead run on electricity. • Ventilation of exhaust air. As air handlers are all-electric, they do not produce exhaust, meaning that no ventilation system is required.