What Is an Air Handler (aka Fan Coil Unit) and Why Do You Need One?

What Is an Air Handler (aka Fan Coil Unit) and Why Do You Need One?
Roger Bakies
Residential Sales Professional

I have been in the residential/light commercial HVAC business for 30 years. I grew up in a sheet metal fabrication shop and have installed, serviced, sold and helped people choose new systems to best fit their needs and lifestyle. I look forward to helping you pick the best fit for your home!

About This Article

What is an air handler and why do you need one? We examine this essential part of an HVAC system and show how it can work in tandem with your heat pump or AC.

Do you know anything about air handlers? If you’re nodding your head yes, good for you. You’re ahead of the game. If you don’t, you’re not alone. Most homeowners don’t understand the workings of an HVAC system.

That’s fine, as long as nothing breaks down or you need a replacement. That’s the time when some specialized knowledge would come most in handy.

We’ve sold tens of thousands of products that make the air warmer, colder, drier, more humid, and less dusty.

Part of our job as HVAC professionals is to demystify the equipment in your home and to educate you on subjects that people are asking about.

One piece of machinery that we don’t see very often is a stand-alone air handler. And if we don’t see it very often, it’s a good bet you haven’t any idea what it is or what it does.

By the end of this article, you’ll know a lot more about it, and how you might benefit from the use of one.

We’ll examine:

  • What Is an Air Handler?
  • Why Do You Need an Air Handler?
  • Types of Air Handlers
  • How Much Electricity Does an Air Handler Use?
  • Air Handlers Need to Rate With Heat Pumps and AC
  • Air Handlers Can Be Configured to a User’s Needs
  • Who Might Benefit From an Air Handler?
  • What Is the Price of an Air Handler?
  • Cost and Choice: What's Right for You?

What Is an Air Handler (Fan Coil Unit)?

An air handler, also known as a “fan coil unit,” is basically a box shaped like a furnace. It has a blower in it, either a variable-speed or an ECM blower. (Electronically commutated motors (ECM) are brushless motors developed by General Electric that are the latest in blower motor efficiency.)

The air handler sits inside of your home, much like a furnace.

It has an evaporator coil, and it can have an electric heater package, which contains heat strips. The evaporator coil is the cooling kit. It can also have an air filter as part of the unit or separate from it.

If you don’t have a furnace, this is an essential part of an HVAC system. A furnace is technically an air handler. It doesn’t just produce hot air in the winter; it has a blower that moves air, so it’s busy in the summer months as well. It works in conjunction with your air conditioner or heat pump to remove the hot air from your home while its blower circulates conditioned air.

The electric heat strips in an air handler are like the heating element in a toaster. You supply electricity to the strips and they turn red.

There may be up to five banks of electric heat. The internal controls will moderate those so they don’t come on all at once, otherwise, your lights would dim. The air handler itself has only one stage: it either heats at 100%, or it’s off.

Air handler

Why Do You Need an Air Handler?

An air handler’s main purpose is to move air through the ducts and your home. Pretty simple.

An air conditioner can expel as much hot air as it can. Your furnace can generate lots of heat. But without a blower, the inside air would stagnate. It needs a force behind it so that your HVAC can do its job.

You would usually pair an air handler with a heat pump or an air conditioner. If you ever need emergency or auxiliary heat, you can always add the strips.

Other items can add to your indoor air comfort. Humidifiers, dehumidifiers, a HEPA filter, and air purifying devices such as a Reme Halo can be added as necessary.

Types of Air Handlers

Like a furnace, air handlers come in different types. You can buy a single-speed, two-speed, or variable-speed version. A single-speed, which is the cheapest option, has two different modes: 100% on or 100% off. A two-speed has a setting lower than 100% and can help circulate the air in your house more evenly.

Variable-speed air handlers have multiple blower settings, from 100% capacity to as low as around 40%. They modulate between speeds to provide optimal comfort. The exact number of speeds will vary depending on the brand and model.

Because it can run at a slower speed, it will do an even better job of conditioning all the air in your home. You’ll see lowered energy costs, increased comfort, and have a unit that has less starting and stopping.

Let’s say you have a multi-level home, and the second floor is less comfortable (in the winter, this would mean it’s colder). Once the main floor is heated, the variable speed operation from your air handler can keep that temperature steady while also allowing the heat to spread throughout the home.

The result is a home without hot and cold spots, or wild spikes in hot or cold.

Air handler

How Much Electricity Does an Air Handler (Fan Coil Unit) Use?

The power required for the blower part of the air handler isn’t much different than a furnace blower. The heat strips are a different matter.

It takes a fair amount of electricity to get those heat strips glowing. If we examine a 110-volt electric heater, that’s about 1500 watts. A toaster or hairdryer isn’t far from that. A 1500 kW electric heat package for your air handler is about the same as 15 electric heaters. That would be like an electric heater in every room.

That’s very costly to operate. That’s the main reason air handlers are paired with heat pumps, which provide heat efficiently.

The heat strip packages come in 5, 7 ½, 10, 15, 20, and 25 kW. As you need more heat strips, the air handler needs to be bigger.

Air Handlers Need to Rate With Heat Pumps and AC

This is part of the complexity of HVAC systems: Just because you want or need a certain thing doesn’t mean you can just purchase it and you’re ready to go. Certain equipment has to be matched with certain other equipment.

For instance, air handlers have tonnages that match the heat pump. If your heat pump is sized for 4 tons, your air handler needs to be the same. We talked about the AHRI match. If you don’t have an AHRI match, it may not work correctly, and the manufacturer won’t warranty the system. This is because indoor and outdoor units on electric must “rate.”

“Rating” means the settings on the air handler need to match the available settings on your air conditioner or heat pump, or they won’t function efficiently. If they are mismatched, they probably won’t work well together because they’re not communicating well.

For instance, a heat pump might have a variable-speed fan, which means that it can run at dozens of different speeds. But if it’s paired with an air handler with a blower that has only one speed, the variable-speed function is worthless.

Air handler

Air Handlers Can Be Configured to a User’s Needs

Just like furnaces, you can configure the air handler in a variety of positions. They are called multi-position. In some homes, the furnace is in the basement, so air would blow air up and out the top.

In other homes, the furnace is in a crawl space or on a slab, the system sits on the floor and the air is blown down into the duct system. Or you can configure it so that air blows out from either side.

Who Might Benefit From an Air Handler?

If a homeowner has some sort of heat they’re happy with and don’t want to change (such as baseboard), and they want to install air conditioning, they would be a candidate for an air handler The same is true if you have electric baseboard heat, and you don’t have gas, and you want air conditioning in a ducted system. That would be a good time to convert to an air handler with a heat pump.

Or if you’re building a house and you don’t want to or cannot use gas, you can go all-electric without a furnace. The downside of that is your electricity bills will skyrocket in the winter. Those heat strips will get a workout when it gets really cold.

How Much Does an Air Handler Cost?

An air handler can cost anywhere from $2900 - $5800. This price includes installation. The price variation is due to the unit’s capacity and the type of blower it has. Heat strips are an additional $300 - $600 installed.

Air handler

Cost and Choice: What's Right For You?

We know: This is no small investment for a piece of HVAC. 

The only way to know the exact cost of an air handler is to schedule an in-home estimate with an

experienced professional. But when you know factors that affect the cost, you can ask more informed questions and make a better-informed decision when the time comes.

As you continue to research replacement air conditioners, here are some articles that can help you learn more before you decide on a system:

READ MORE:

How Much Does a Heat Pump Cost to Replace in 2021?

Heat Pumps 101: The Ultimate List of Heat Pump FAQS

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