Guide to Buying a Ductless Air Conditioner

The popularity of ductless air conditioners continues to grow as consumers search for
alternatives to window units and conventional central air conditioning systems. Sometimes
referred to as "mini splits," ductless technology provides a cost effective alternative for
applications where the use of ducted A/C equipment would be impractical.

The Basics of Ductless Air Conditioning

ductless air conditioner operates in essentially the same manner as its ducted counterpart.
The heart of every A/C system includes a compressor that applies force to low pressure
refrigerant and transforms it into a high pressure gas. The condenser and fan work together to
dissipate the accumulated heat, and the refrigerant emerges as a high pressure liquid. At the
evaporator coil, the liquid extracts heat from the indoor air and the resulting low pressure gas is
pumped back into the compressor to complete the cycle.
Like a conventional split system, ductless air conditioners include an outdoor condensing unit to
help minimize interior noise. While central air conditioners employ a single air handler, blower,
and evaporator coil, mini split systems house all three components together in separate indoor
units that are strategically placed throughout the building. Stylish enclosures are hung on
interior walls or placed in the ceiling, which completely eliminates the need for ductwork in the
air distribution design.

Ductless Configurations


Ductless split systems are available in a variety of configurations through the utilization of
different components. When assembling a complete system, it is important to understand the
various equipment options:
  • Wall Unit: Indoor fan coil unit that hangs on a wall
  • Ceiling Cassette: Indoor fan coil unit-recessed in ceiling with exposed grille
  • Single Zone Condenser: Outdoor condenser paired with single zone indoor unit
  • Multi-Zone Condenser: Outdoor condenser that can serve up to four indoor units
  •  Heat Pump: Includes a reversing valve to provide heat

Applications of Ductless Split Systems

Ductless split systems are extremely versatile and can be used to provide cool comfort for a
variety of different applications:
  • Whole House: In older homes without ducting, or new construction, ductless technology accommodates modern architecture, reduces installed costs and saves energy
  • Room Addition: Where central A/C system has insufficient capacity to cool the addition
  • Garage, Attic, or Basement Conversions: In instances where installing ductwork may be
  • impractical or undesirable
  • Supplemental Cooling: In homes where the central A/C system is undersized or the ductwork has been compromised
In addition to replacing central air conditioning equipment, ductless systems are often a
suitable alternative to room air conditioners. Since the evaporator and condenser are separate
components, mini splits are much quieter and more energy-efficient than room air
conditioners. Security is also enhanced since ductless components do not need to be positioned
in an open window.


Advantages of Ductless Technology

Ductless air conditioners have many advantages when compared to traditional central air
conditioning systems. The growing popularity of the technology is driven by a variety of factors.
Energy Efficiency
Conventional air conditioning systems utilize a network of interconnected duct runs that are
used to deliver conditioned air to the various sub-domains within the home or building.
Constructed of metal or flexible plastic, ductwork is a relatively inefficient distribution method.
Connections are prone to leakage, and flexible duct can sag over time. The loss of efficiency
from a poorly designed or improperly installed air distribution system can account for as much
as 30 percent of total system energy consumption.
In contrast, point-of- use air handlers deliver conditioned air directly into the room without
passing through thermally inefficient ductwork. By positioning the air handler directly at the
delivery point, ductless systems increase efficiency by eliminating friction loss, leakage, and
design deficiencies. Additionally, the placement of individual fan coil units throughout the
building creates independent cooling zones that can be adjusted through individual
thermostats to meet the lifestyle demands of the occupants. Zone cooling allows for higher
temperature settings in unoccupied rooms, which can result in substantial energy savings.


Cost Savings

Although the cost of ductless air conditioning equipment may be higher when compared to a
conventional system or a room air conditioner, ductless split systems are very cost effective
over the life of the equipment. In new construction, eliminating ductwork and the air
distribution system can result in substantial cost savings. Ductwork often causes unnecessary
building design modifications that are eliminated by using ductless equipment.
Room air conditioners are generally noisy and inefficient. Ductless split systems provide quiet
comfort, enhanced cooling options, and superior energy efficiency ratings that can result in
significant savings in annual utility costs.

Health Benefits

Over time, dirt and debris accumulates in the interior of an air distribution system. When
moisture is added through condensation, biological agents have the nutrients they need to
propagate. Mold and fungi can degrade indoor air quality and aggravate allergies, asthma, and
other respiratory problems. Window units are almost impossible to completely seal, which
allows outdoor contaminants to enter the livable area in a home or office.
The evaporator coil in a ductless system is accessible and easy to clean. The absence of
ductwork deprives harmful organisms of the environment they need to flourish. Eliminating the
dirt and debris that accumulates in ductwork can help keep a home cleaner, healthier, and
smelling fresh.


When a central air conditioner malfunctions, the entire structure is affected, and the indoor
temperature will remain uncomfortable until the unit is repaired. In areas where summer heat
is extreme, this can create health risks for the elderly and small children. Since ductless systems
often employ multiple condensing units in different zones, occupants can move to the areas of
the home or office that are still air conditioned.

Inverter Technology


Ductless split systems are unique in that the most recent manufactured products include
inverter technology. When a room has a light cooling load, a variable speed motor allows the
compressor to run more slowly, which reduces energy costs. When the room has a higher
cooling demand, the motor signals the compressor to run at a higher speed. In addition to
saving energy, the unit is far more responsive and quick to provide a measured amount of
conditioned air into the living space.


Understanding SEER Ratings

Every air conditioning unit has an associated Seasonal Energy Efficiency Rating (SEER) that is
used to measure its performance relative to other brands and models of equipment. These
ratings were developed and adopted to provide consumers with a meaningful way to compare
the energy usage of the equipment produced by different manufacturers. SEER ratings are
percentage based, so a 16 SEER system is about 37 percent more efficient than a 10 SEER
system. In practical terms, for every $100 spent on fuel costs for a 10 SEER air conditioner, a 16
SEER system would cost only $63.

Features of Ductless Split Systems

Ductless split systems offer a wide array of features and enhancements that vary by model and
manufacturer. The most common features are included in many entry level models such as:
  • Programmable timer and sleep mode
  • Multiple fan speeds
  • Auto-shut flaps on wall units
  • Louvre sweep mode
  • Auto-restart after power outage
  • Reusable filter
  • Auto changeover if configured as a heat pump
  • Wireless controller
  • Optional hard wired thermostat

Installation of Ductless Split Systems

The installation of a single zone ductless split system is a relatively straightforward process. The
condensing unit must be positioned outdoors with enough clearance for sufficient air
circulation. The manufacturer will provide specifications for the maximum refrigeration line
length allowed between the condensing unit and the indoor evaporator.
A 3-inch hole must be drilled through the wall behind the location where the indoor unit will be
positioned. The hole must protrude through the exterior wall to the outside of the building.
Copper refrigerant lines are run from the indoor unit through the hole in the wall to the
condenser and then attached with supplied couplings. Rubber or foam insulation can be used to
insulate the refrigerant lines. The drain pipe should be connected to the appropriate port and
follow a pathway to the exterior of building. The electrical connection to the compressor in the
condensing unit completes the basic installation process.
For final electrical connections and charging the system with refrigerant, it is important to
contact a licensed and certified HVAC technician. Substandard wiring or an improper refrigerant
charge can damage the system, void the warranty, or cause severe injury.


Ductless air conditioners offer superior energy efficiency, extremely low noise, and enhanced
levels of comfort when compared to traditional central air conditioning systems. By eliminating
ductwork, indoor units can be located strategically to create multiple, independent cooling
zones. When selecting a ductless system, it is important to determine if a heat pump or straight
cool unit is appropriate. Single zone systems are most effective, but multi-zone systems
working off a common condensing unit are more cost-effective.
Source: to-Buying- a-Ductless- Air-Conditioner-