What Is a Ducted Mini Split?

Mini-split air conditioning systems can be ductless or ducted. A ductless system saves space with indoor units mounted on walls, which are connected directly to an outdoor unit via tubing. For those concerned about the aesthetics of large indoor units, a ducted mini-split heat pump can be installed.

It uses a short run of ducts connected to a small outdoor unit. Such a configuration can serve one or several rooms. This benefits homes that already have ductwork yet still provide a convenient alternative to central air conditioning systems.

How the System Works

A ducted mini-split system has an outdoor unit and an indoor air handler. The indoor unit is designed to be installed above the ceiling (ductless units are typically wall-mounted). Air handlers can also be exposed or suspended from the ceiling or installed as cassette units. A supply air outlet may be connected to a duct. However, the return air inlet can be connected to a plenum box or free return in which no return air ducts connect to the rear of the unit.

Generally, the system works on the principle of using a compressor, which is contained within the outdoor unit. Here, R410A refrigerant is compressed and pushed through a heat exchanger. Copper tubes deliver refrigerant to the indoor unit, where it expands and flows back to the exchanger to release heat outside and cool the air indoors. By using a reversing valve (via the remote control), the mini-split can heat or cool your home.

Ceiling Mounted Ducted Unit

The typical ceiling unit has a large opening in the front for connecting a supply duct. A filter is located in the back, where a return air plenum box can be connected if a ducted return is also installed. Four support brackets allow you to hang the unit from a soffit slab (galvanized iron rods help hold the unit in place). The unit also has two pipe connection ports for refrigerant lines and one port for the drain pipe.

Ducted Mini Split Benefits

If you’re looking for an alternative to a traditional central AC and aren’t sold by a ductless system, a ducted mini-split can:

• Be more efficient than a central AC.
• Reduce the cost of your monthly bills.
• Provide a more aesthetic solution than a ductless mini-split.
• Reduce the amount of air leakage compared to a whole-home AC.
• Cool more rooms than a ductless system.
• Improve indoor air quality, since there’s less ductwork.
• Enable zoning so each room can be set at a different temperature.
• Utilize the existing HVAC ductwork, easing installation.

Installation

The major difference between ducted and ductless mini-split installation is the use of ductwork for air distribution. The amount of ductwork needed depends on the application. A ceiling ducted unit may contain an insulating material and optionally a secondary drain pan below, in case the built-in drain pan clogs (which can damage the ceiling).

Flexible branch ducts and supply air plenum boxes help deliver conditioned air to individual spaces. A supply air diffuser, refrigerant pipes, and cables also connect to the ducted unit. One option is to use linear diffusers, which run as long vents across the ceiling.

A ducted mini-split also differs in that you can use a remote controller or wired controller. A wired control device doubles as a thermostat, so you can control room temperature, operating mode, fan speed, and scheduling. Wireless controllers may not offer as much functionality but are convenient to have.

There are also different methods of installation. The configurations of a ducted mini-split can include:

• Hotel Room Style: Contains one supply air outlet and one return air inlet, and is suited for small rooms similar in size to hotel rooms.
• U-Turn Style: In a small room, this rotates the ceiling ducted unit so, on the drop ceiling, the supply and return grilles are in a straight line.
• Conventional: The main branch and branch ducts can be combined to increase capacity and cool an entire house, but smaller units for each room can also be installed.

Another option is to put the system in an unconditioned attic. However, external static pressure is a factor, as it affects the fan’s ability to move air through the system. If external static pressure is too low, certain rooms may not be cooled enough.

Are You Ready for a Ducted Mini Split?

In general, a ducted unit is more suited for a larger room, and for those who prefer not to install air handlers on their walls. Cooling your entire house with one unit is possible. However, it will have only one thermostat so adjusting the temperature for each room can be a challenge. Accessories can allow for zoned control, but with a fixed airflow supply, the results may be unpredictable. For larger homes, multi-zone mini-split systems can provide increased control over single-zone ones.

Contact Oregon Ductless

A Daikin 3D Dealer and Mitsubishi Diamond Dealer, we’re one of the leading ductless and ducted mini split installation experts in the Portland, OR, area. We can help you install or convert to a mini-split AC and also install traditional HVAC systems. Contact us online or call 503-832-5497 to learn more about our products, installation services, and financing.