What Is a Ductless HVAC System?

Ductless hvac unit

Ductless Heating and Air Conditioning (HVAC) systems can be the perfect solution for that room which is never quite cool enough or for that new addition you are building onto your house. Ductless HVAC systems (or mini-split systems) are wonderfully quiet, energy efficient, and provide consistent room comfort. They can JUST provide AC; or, like a heat pump, deliver both heating and air conditioning. But the factors that prompt a decision to install can be very different for every Knoxville small business or homeowner.

Here in Tennessee, we also call these systems mini-splits, multi-splits, and variable refrigerant flow systems. Call AA-Air Company for a recommendation from one of our heating and cooling professionals on where a ductless air conditioner might work best if you think could use some cooling help.


A ductless HVAC system is commonly considered where baseboard heating or window AC units would originally be considered, but budget allows for a better, more permanent solution. Unlike your grandmother’s window units, ductless units are much less vulnerable to air leakage and security issues, because they only require a small hole in the wall, and are permanently mounted. Ductless systems work, obviously, with no ducts; unlike a traditional central HVAC system that uses them to carry air to your home’s room vents. Instead, this system has a wall-mounted indoor unit and an outdoor condenser unit located against the house or building. This makes it highly adaptable to many rooms and needs.

This system is highly versatile, as its compact size and minimal-installation requirements offer many options for its use and location. The inside unit is typically mounted high up on a wall in the room where cooling (and/or heating) is needed. A small hole, approximately three inches in diameter, is cut to the outside where the lines providing electricity, drainage, and refrigerant can come through from the outdoor unit.

A heater for your home is, of course, still needed. These ductless systems can be one of three types:
AC only for when the building’s existing furnace is providing adequate heat, and air conditioning is the only feature needing to be added.
Heating and cooling as a standard heat pump; great for when an alternate source of heat is needed to supplement the existing stoves or furnace in winter.
A hyper-heat model can keep up with much colder temperatures like we sometimes experience here in East Tennessee, so is recommended if another heat source is not available.

Many older homes in historic areas have never been updated to central HVAC. Often, they might have a furnace for heat and homeowners have relied on window units to keep the house cool. A ductless air conditioner might be the perfect solution for providing much needed air conditioning while utilizing the existing traditional furnace for heat, and without fully remodeling the home to accommodate a modern fully ducted system. Sometimes, finding adequate space to run an efficient duct system in an older home can be a challenge.

Retrofit Solution

A ductless AC unit is also the best option for a room that’s never quite cool enough, no matter how much you change your thermostat’s set temperature. These units are often installed in bonus rooms, especially the ones that are in a finished attic space over a garage. Imagine being able to control just that room’s temperature to make family night watching movies a comfortable occasion. Maybe your master bedroom has big windows that face southwest, and the room heats up in the summer evenings. A mini-split might be the best solution to cool it down to be able to sleep comfortably without making the rest of the house too cold.

Maybe you are about to add a new small accessory dwelling unit (like a mother-in-law apartment) on your property. You might consider, especially if you are constructing the building direct on slab, having a zoned ductless system quoted and comparing it to a traditional ducted HVAC system. Initial construction costs can be lower (because you are not adding ductwork), installation is much faster, and lifetime maintenance can be less cumbersome.

Controlling the construction costs of an addition can be challenging these days. One way might be to eliminate the need to expand and re-engineer your existing whole-house heat and air and instead have a professional from AA-Air work with your contractor to strategically place a ductless unit to serve the new living space.

Energy Efficiency

Many homes are now being designed for comfort with multiple units, or “zones,” throughout the entire house. If you have these multiple zones in your home, you can control the temperature on a per-zone (ie. room) basis, instead of cranking up the air conditioner for your entire home. Perhaps you have a space you use intermittently: guest quarters or short-term rental space. Let your guests control their space without impacting the rest of the house, and only incur added cooling costs when that area is occupied.

With a traditional air conditioner, you can be losing 20 percent or more of your warm or cool air through your ducts via holes and leaks. The ductless air conditioner completely bypasses that issue and offers the efficiency of indoor geothermal without the large initial cost to install that particular type of system. Additionally, most ductless HVAC units have inverter-driven compressors that ramp up and down based on the needs of the indoor environment to maintain comfort. A traditional HVAC compressor will shut off and on, using a lot of energy for starting back up repeatedly. This makes them highly energy efficient. You’ll get lower power bills in return, but the payback period depends on your climate, your use of the system, and your local electricity rates.

These systems are becoming more popular and are actually very cost effective. According to ENERGY STAR®, they can save you up to 30 percent on your cooling energy bills, compared to air conditioner window units. You might qualify for a federal tax credit or local utility incentives as well. Check with your local utility company and tax professional for more information on these programs.

Low Maintenance

Ductless air conditioners are generally easy to maintain. While they do require consistent maintenance in the form of frequent (monthly, or more often with pets or smokers) filter washing, the homeowner can certainly do this. The installation, however, definitely requires a professional for many reasons including proper refrigerant handling, and warranty considerations.

Our certified technicians at AA-Air Company have the expertise required and would be happy to answer any installation questions you may have. Always be sure any installing company has a license before hiring them for the work. There are nuances to any installation that only a licensed contractor can know and address.

Call AA-Air Company for Ductless Air Conditioning Help

To get maximum comfort and benefits from a ductless system, you will want to work with an experienced professional to properly size and install the system. Sizing and zoning the units will insure it will work as intended. But installation can be just as important: penetrating the wall, locating the outdoor unit, and running the lines for sensitive electronics and refrigerant are all crucial to the system’s performance and warranty.
If you are constantly reaching for that glass of sweet tea to help cool you down in one for more of your rooms here in Knoxville, TN, or if you are in the middle of planning an addition or converting your garage to a family room, definitely take a look at a ductless air conditioner. It could answer more than one need for you. Call us at 865-689-5290 or contact us online today.

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