
The first HVAC company I worked for was a learning experience. Regardless of your background, there’s a ton to learn about the mechanical complexities of heating and cooling.
Air handlers were one of the last items I confidently learned about, because their place in an HVAC system isn’t as well-known as furnaces, air conditioners or even heat pumps.
In the years since, I’ve discovered that customers have this same confusion. They may not even know they have an air handler installed in their home! And so our technicians often have to explain what it is and what it does within a heating and AC system.
If you want to skip that confusion and jump to the head of the class, this article is for you!
What is an Air Handler?
At its core, an air handler circulates conditioned air from your air conditioner or heat pump. It handles the air, as the name implies. However, air handlers also house a range of parts that perform other functions related to both heating and cooling. Thus, an air handler serves several functions in most homes.
We’ll go into detail on each of those parts and functions below.
How Do Air Handlers Work?
The core process that takes place inside an air handler is the circulation of air through the home. This is facilitated by a blower motor and attached fan.
The air handler is connected to other parts of the system, such as the air conditioner or heat pump, as well as to the home’s ductwork. In this way it can transfer the conditioned air as needed throughout the home.
This is the function of an air handler that gives it its name, but it’s not the only function it serves.
The air conditioner or heat pump’s evaporator coil is stored inside the air handler. This is an element of your cooling system, one that absorbs heat from the air around it and shunts it outside before recirculating the cooled air. Your air handler acts as a casing for this vital part.
Additionally, air handler can be directly involved in the heating process.
Take, for example, a heat pump system. Many air-source heat pumps struggle to provide sufficient heating during the coldest months. In these instances, an air handler can provide supplemental heat.
Electric heat strips can be installed inside an air handler that provide additional heating energy to a home. They don’t operate by removing heat from one area and transferring it, like an AC or heat pump, but rather the coils simply heat up, much like an oven or toaster.
Air Handler vs. Furnace
Furnaces and air handlers often serve many of the same functions, so it can be easy to confuse the two. Furnace usually refers to a gas-fueled heating system, whereas air handlers use electric heating strips (which need to be installed separately).
Air handlers also tend to be paired with heat pumps, whereas it’s more common to see furnaces paired with air conditioners. This isn’t always true, but often results in efficiency gains with proper equipment pairing.
The actual casing of furnaces and air handlers often house many of the same parts, so their total function has some overlap. But oftentimes people will call their heating unit a furnace when in fact it’s an air handler.
Air Handler vs. Air Conditioner vs. Heat Pump
Air handlers do not condition the air like air conditioners or heat pumps. Their role is to circulate conditioned air throughout the home.
They also house the evaporator coil that’s a major part of an AC unit or heat pump.
Since air handlers operate on electric power for their heating capacity, they’re often paired with a heat pump instead of an air conditioner. However, both types can technically function alongside an air handler.
What HVAC Equipment Interacts With the Air Handler?
What doesn’t interact with the air handler in an HVAC system might be a shorter list.
Joking aside, it’s important to realize that a heating and cooling system is just that: a unified system of equipment. Thinking of an air conditioner or heater as separate from the whole paints the wrong picture.
So what all is involved? Glad you asked…
You’ll adjust your thermostat to the desired temperature. After this, it sends an electrical signal through wiring to the control panel on your system. This starts the blower motor, which controls the blower fan.
Depending on whether or not the system is heating or cooling, several things could happen. The refrigerant in the air conditioner or heat pump might start flowing, absorbing heat from the evaporator coil housed in the air handler. While heating, this will likely also be accompanied by a heating of the electric coils in the air handler.
The air – heated or cool – will pass through the air filter, and into your home via the ductwork and air vents. The return air vents will then run untreated air back into the system for heating and cooling.
Several sub-processes and mechanical parts are involved in each of those major steps, but those are the broad strokes of the process. And the air handler sits at the center of all of them!
Types of Air Handlers
When we discuss types of air handler, we’re usually talking about the type of blower motor it has, which also determines several other variables of the system in terms of its controls and power levels.
The motor, which controls the fan, regulates airflow in the system. Your simplest motors operate at a single speed. More sophisticated ones – two-stage or multi-stage – can change their power level to adjust to the heating and cooling needs of your home.
This can be quite powerful, since the gains in energy efficiency over an entire year can equal several hundred dollars for most households.
Multi-stage blower motors are more expensive to start, but if you use your system frequently or anticipate staying in your home for several years, they can pay for themselves over time in both money and comfort.
Installing a New Air Handler
We’ve mentioned a few times that air handlers are often paired with heat pumps in electric systems. This isn’t by accident, because improperly paired equipment can be a massive loss of efficiency and comfort.
As a result, it’s somewhat rare that we recommend you replace your air handler by itself. More often, when you replace your air handler, you’ll want to install an entirely new HVAC system, generally (but not always) including a heat pump.
It’s not that installing only an air handler can’t help. But the benefits of doing both at once are easy to point out:
- Both pieces of equipment will take advantage of any upgrades to the blower motor, increasing efficiency year-round.
- More even heating will be available since the two units are intended to complement each other, based on your home’s energy needs in the winter.
- A dual-fuel (gas + electric) system can often come with increased installation and maintenance costs, and trickier repairs down the road.
- Installing a full system at the same time saves on labor costs relative to installing them separately. It’s more expensive than just replacing an air handler, but less expensive than installing them on separate occasions.
This isn’t to say that you have to install both at once. It’s important to speak with a trusted heating and cooling specialist who has your needs in mind when they make recommendations and suggestions.
Here at CABS Heating and Air Conditioning, we’ve installed thousands of systems and helped customers to feel more comfortable in their homes throughout the year. If you are in the market for a new air handler or other piece of HVAC equipment, we hope you’ll give us a call!