What Is an Air Handler vs heat pump? Essential HVAC Part

There are numerous HVAC industry terms that you may encounter in your lifetime. While knowing all of your home’s HVAC system components is unrealistic, knowing the fundamentals can be beneficial.

You’re not alone if you’ve ever had to ask, “What is an air handler?” Many homeowners are perplexed by this particular HVAC component.


Unlike heat pumps and air conditioners, air handlers aren’t devices that we regularly interact with, which makes them seem a bit mysterious.

In this article, we examine this essential component of an HVAC system, its parts, and how it works. We also lay out reasons why an air handler is necessary, so be sure to stick around!

What Is an Air Handler?

An air handler, also known as a fan coil unit, is an indoor box-shaped unit that’s typically installed with a heat pump or an air conditioner as part of your HVAC system.

It’s usually located inside the roof, basement, or a dedicated closet because it needs to be as close to the center of your home as possible. This location allows for the shortest possible duct length to the various zones of your home, making air circulation much more efficient.

An air handler functions as your home’s lungs, circulating air throughout your home and returning it to the unit to ensure proper ventilation.

While this HVAC component doesn’t heat or cool air, it works in tandem with your heating and cooling system to maintain the desired temperature of the air inside your home. It can also eliminate excess humidity.

What’s more, an air handler is outfitted with air purification filters that remove dust, pollen, and other small particles from the air to regulate the quality of the air inside.

How an Air Handler Works

Air handlers are part of a two-part, split system that connects to an outdoor unit through refrigerant lines. The outdoor unit can be a heat pump, an air conditioner, or a mini-split system that has both heating and cooling functions.

The air handler unit is linked to each room in your house via a supply and return ventilation duct system that recirculates the air inside.

It heats, cools, and purifies the air inside your home by blowing air through the evaporator coil and air filter. Then, it transfers the air to your home via the duct system. This setup ensures that each room in the house is well ventilated and equally warm or cool.

Air Handler Parts

The parts of an air handler unit will vary depending on the HVAC system set up in your home. That’s why we’ve compiled a list of all the basic components of an air handler unit.

Blower Motor

The blower motor is responsible for transferring air from the outside to the inside of the air handler, where it’s filtered and cooled/heated before being circulated throughout your home via the duct system. It can be a single-speed, multi-speed, or variable-speed model.

The types of air handlers available on the market depend on what blower motor model they have.


A single-speed blower has only one fixed speed. It’s like a light switch; it’s either on or off, blowing at maximum speed to cool/heat your house or not blowing at all when your house reaches the desired temperature.

This motor model is the most affordable but the least efficient. It’s more common in HVAC systems that are more than 10 years old.


Multi-speed, or two-speed, blowers can operate at a lower setting than 100% to reduce motor speed.

These blowers are more convenient because their low-speed setting helps reduce humidity levels. It also improves the energy efficiency of the blowers.


A variable-speed motor, also known as an ECM, has multiple blower settings that are activated based on the changing conditions inside your home.

It runs at multiple speeds throughout the day and can operate at full capacity or as little as 25% capacity.

This blower motor is the most energy-efficient, resulting in lower energy bills.

Evaporator Coil

The evaporator coil, also known as the indoor coil, is one of the most essential, if not the most essential, parts of an air handler. It’s the component in charge of the heating and refrigeration cycles.

When the air conditioner is turned on, the coil becomes cold, removing humidity from the air that the blower forces through the coil from the return ducts. As a result, the air blown through your home’s supply ducts is cooler.

The coil is warm when you have the heat pump on. In the same manner, the air passing through the coil heats up and warms your home.

Air Filter

An air filter typically has either higher or lower particles, bacteria, odor, and other air pollutants retention. The retention of the air filter in your air handler depends on the air purity requirements inside your house.

That said, filters do more than just clean and purify the air in your home. They also shield the internal components of the HVAC system from small particles, dirt, dust, and debris.

Most air handlers can house electronic air filters, dehumidifiers, and even UV light, all of which can improve the quality and purification of the air in your home.

So, if you live in an area where there’s a lot of dust, pollution, or free radicals, you can upgrade your air handler to one with better air purification capabilities.

Air Supply and Return Plenum Connections

Air handler plenum connections are box-like empty spaces that connect the supply and return duct systems throughout the home to the air handler.

Their primary function is to draw in, distribute, and expel air.

Reasons You Need an Air Handler

It’s easy to assume that an air handler can’t do anything that a heat pump or air conditioner can’t.

However, without an air handler, the air inside your home would stagnate. The force of the air handler’s blower circulates the air in and out of the HVAC system and your home.

What’s more, air handlers reduce the use of energy required in a heat pump or air conditioner, making your HVAC system much more energy-efficient.

Keep in mind that an air handler’s capacity and SEER must match those of the heat pump or air conditioner to which it’s connected. Mismatched systems are at least 30% less efficient, according to the Air Conditioning, Heating, and Refrigeration Institute (AHRI).

If you’re still not sure whether you need an air handler, you can consult with a professional HVAC technician. A professional can assess your HVAC system and home to determine whether an air handler is necessary.

In Conclusion

The first step to becoming a wiser homeowner is to ask questions like, “What is an air handler?”

An air handler is the lungs of your home. It’s what makes your HVAC system more efficient, your home’s air cleaner, and you happier. It draws in outside air, filters it, cools/heats it, circulates it through your home, and then inhales it back in to purify it.

Now that you know how essential an air handler is to your HVAC system, you can choose the best one for your system and your home.