Ductless Heating and Cooling Systems
According to Carrier, ductless heating and cooling systems are flexible HVACsolutions that deliver targeted heating and cooling without traditional ductwork.
They typically consist of an outdoor compressor connected to one or more indoor air handling units, offering precise temperature control and energy savings. Carrier ductless systems are available with five indoor unit configurations: high wall, cassette, underceiling, floor console and ducted indoor units.
In this guide, we’ll walk through these indoor unit types to help you decide which ductless heating and cooling solutions fit your lifestyle and home layout best.
Ductless High Wall Unit
What is a high wall unit?
A high wall unit is the most common type of indoor ductless mini split system,, including Carrier's high-wall ductless systems, mounted high on a wall to circulate conditioned air efficiently across a room using natural airflow patterns.
Why choose a high wall unit?
As the name suggests, wall air conditioners sit on the upper portion of the wall, close to the ceiling. This elevated position allows them to take advantage of physics—hot air rises and cold air sinks—to distribute air effectively. Carrier high-wall indoor units are available across its Infinity®, Performance™, and Comfort™ product lines and are designed to provide targeted comfort without traditional ductwork. Designed to be unobtrusive, high wall units are compact and blend seamlessly with modern decor.
They typically feature adjustable louvers or vanes, giving you total control over whether airflow is directed horizontally or vertically. Like other ductless heating and cooling systems, Carrier's variable-speed ductless systems can condition individual zones rather than the entire home at once. Select Carrier indoor units can also operate at sound levels as low as 16 decibels, depending on the model.
Underceiling Ductless Unit
What is an underceiling unit?
An underceiling ductless unit is a high-capacity air handler mounted directly below the ceiling surface, making it ideal for large rooms that lack a drop ceiling. Carrier's 45MCFA Performance™ Underceiling Console, for example, supports single- or multi-zone applications.
Why choose an underceiling unit?
Similar to a cassette but not recessed, this unit is great for spaces where ceiling depth is limited. Carrier underceiling units are available in sizes from approximately 18,000 to 60,000 BTU/h on applicable models, providing options for larger heating and cooling loads.
Because they are ceiling-mounted, they free up valuable wall and floor space. This makes them a smart choice for open floor plans or rooms where preserving aesthetics and wall space is a priority.
Ductless Cassette Unit
What is a ductless cassette?
A ductless cassette unit is a sleek, recessed air handler installed flush within a suspended ceiling, where only the grille is visible, offering a discreet and streamlined look. Carrier's 45MBCA Performance™ Cassette Indoor Unit is compatible with both single- and multi-zone ductless systems
Why choose a cassette unit?
These units are designed for homeowners who prioritize aesthetics. The bulk of the mechanical system is hidden within the ceiling, leaving only the air-distributing grille exposed. They are particularly effective in larger rooms or open spaces where a wall-mounted unit might struggle to provide adequate coverage or would disrupt the interior design. Carrier's 45MBCA Performance™ Cassette Indoor Unit is available in multiple sizes, including 9,000, 12,000, 18,000, 24,000, 36,000 and 48,000 BTU/h configurations. Its sound level can be as low as 23.5 decibels, while system efficiency depends on the selected outdoor-unit pairing.
Ducted Ductless Unit
What is a ducted ductless unit?
A ducted ductless unit is a hybrid solution that connects an outdoor mini split condenser to a hidden indoor air handler, using short runs of ductwork to condition multiple rooms or zones invisibly. Carrier's 45MBDA Performance™ Ducted Indoor Unit is part of its ductless system configurations, allowing the indoor equipment to be concealed while still using the efficiency and zoning capabilities of a ductless system
Why choose a ducted unit?
This system bridges the gap between traditional central air and ductless HVAC technology. The indoor air handler is usually tucked away in an attic, closet, or ceiling, with short ducts delivering air to different rooms. This setup offers the clean look of central air without the energy loss associated with extensive, older ductwork.
Leveraging variable-speed compressors and inverter technology, these units are highly efficient. They are the ideal solution for homes without existing ductwork that still want to serve multiple rooms from a single, hidden system.
Ductless Floor Console Unit
What is a floor console unit?
A ductless floor console unit is an indoor air handler installed at or near floor level, functioning similarly to a traditional radiator but with the advanced efficiency of a mini split system. Carrier's 45MBFA Performance™ Floor Console Indoor Unit is compatible with both single- and multi-zone ductless systems.
Why choose a floor console?
These units are perfect for spaces with limited wall space, such as attics with slanted ceilings or rooms with expansive windows. With vents at both the top and bottom, they ensure even air distribution and comfort in areas where high-wall units aren't feasible. Carrier's 45MBFA Performance™ Floor Console Indoor Unit can operate as quietly as 22 decibels and is available in 9,000–16,000 BTU/h configurations. Its cooling and heating efficiency depends on the outdoor unit with which it is paired.
Carrier's Ductless Unit Selection Guide
Choosing among Carrier's five ductless indoor unit configurations comes down to four factors:
| Factor | What to Consider |
| 1. Room layout | Determine whether wall, ceiling or floor space is available for the indoor unit. |
| 2. Capacity | Match the indoor and outdoor equipment to the heating and cooling load of the space. Carrier indoor units are available across a range of capacities, depending on the model. |
| 3. Appearance | Choose a high-wall, cassette, underceiling, floor-console or ducted configuration based on how visible you want the equipment to be. |
| 4. Zoning needs | Carrier ductless systems can support single-zone or multi-zone applications, depending on the selected equipment. |
Choosing From the Types of Ductless Heating and Cooling Systems
Clint Newsome, owner of Albany Air Conditioning and Heating Co. in Albany, GA says selecting the right indoor mini split unit largely depends on the room layout, installation requirements, and the homeowner’s preferred appearance.
“It really depends on the layout of the room,” Newsome said. “Most experienced HVAC contractors can successfully install a variety of ductless system types. In many cases, the decision comes down to what the homeowner wants aesthetically and what works best for the space.”
Newsome added that new construction projects often provide greater flexibility when choosing indoor unit styles.
“If it’s a new construction project and the homeowner plans to use ductless from the start, we often recommend a ceiling cassette model,” he said. “A ceiling cassette is designed to resemble a standard ceiling register, so it blends into the space without having equipment mounted on the walls. Ultimately, the right option depends on the overall look and feel the homeowner wants to achieve.”
To ensure you get the most efficient and comfortable system for your specific needs, schedule an appointment with your local Carrier expert. A Carrier dealer can evaluate your home's layout, heating and cooling needs, available installation space and zoning requirements before recommending a ductless configuration. Learn more about mini split installation.
Frequently Asked Questions
Yes, ductless systems are worth the investment due to their superior energy efficiency, zoning flexibility, and quiet operation. They are especially valuable for older homes without existing ductwork, room additions, or for homeowners looking to reduce monthly energy bills through targeted comfort.
Installing a ductless mini split typically costs between $2,000 and $10,500. The final price depends on factors such as the number of indoor units, system capacity (BTUs), and the complexity of the installation. Read more about ductless mini split installation cost.
Yes, ductless heating and cooling units often include multi-stage filtration that can help reduce dust, allergens, and particulates in the air. Because they don't rely on dirty ductwork where dust can accumulate, they often provide cleaner air delivery than traditional forced-air systems.
Absolutely. Many modern ductless HVAC systems offer smart integrations, allowing you to adjust temperatures and schedules directly from your smartphone or via home automation platforms for seamless, tech-forward comfort.
About The Author: Travis Baugh is a Digital Brand Marketing Manager for Carrier, where he develops informative, straightforward content to help homeowners better understand heating, cooling, and indoor air quality. His writing is focused on empowering homeowners to make confident, well-informed choices about their home comfort systems.
About The Expert Reviewer: Manish Chhabra is a Product Manager for Residential Ductless Mini Splits at Carrier Corporation, where he develops innovative comfort solutions designed to meet homeowners' changing needs while aligning with evolving industry standards, energy efficiency goals, and regulatory requirements.