“Ductless systems offer individual temperature control, installation flexibility, energy efficiency, and quiet operation at a level that really sets them apart from other types of HVAC systems,” said Marc Zipfel, director of product marketing, Mitsubishi Electric Cooling & Heating. “Ductless units are extremely energy-efficient, meaning end users can save money on energy bills over time.”

Space

A ductless system conditions a room without the use of ducts, saving space and allowing the unit to be retrofitted into spaces absent of ducts. Ductless mini-splits can be designed to cool several rooms, mimicking the sophisticated zone control of modern central air. The technology has especially been a hit in areas where real estate space is at a premium.

“Some multi-split ductless systems can have as many as four indoor air handling units for four zones or rooms attached to one outdoor unit,” said Christopher Wickman, marketing manager, ductless split systems, Carrier. “Since each zone or room has its own control, the homeowner can save energy and money by conditioning only the occupied spaces.”

Installation

Ductless systems are also gaining in popularity due to their simple installation. A qualified contractor can usually install the units in less than a day. Since there is little to no ductwork required, there are no worries about duct or ceiling issues interrupting the process. The unit mounts discreetly within the desired space, while a set of small refrigerant lines and power wires connect to the outdoor unit through a small opening in the wall.

“The ease of installation is a big advantage to the consumer and contractor,” said Don Wojcik, senior manager of Eastern distribution sales, LG Electronics. “For retrofit applications, it is easy to add the units, especially in older buildings that have never been equipped with air conditioning before.”

Zoning

In a central air conditioning system, refrigerant is pumped from the outdoor condenser coil inside to a single indoor coil, from which cooled air is distributed to each room through a system of ducts. In many houses and businesses, the amount of cold air in one room cannot be regulated without changing the temperature of every room in the building. Ductless systems allow an alternative to this practice, as users control the amount of air introduced to each room through each indoor unit. Multiple variations are available, creating single-zones, dual-zones, tri-zones, quad-zones, and more based upon the number of indoor installations.

“Efficiency is achieved through zoning,” said Mike Delwiche, director of sales, room air products, Heat Controller. “Increases in energy costs are driving the need for zoned cooling, and mini-splits help meet that need. The air handler is dedicated to the room being conditioned, which can be kept at a temperature and humidity level different from the rest of the house or building. A unit in a bedroom or a home office, for instance, can be easily programmed for the times when the room is occupied.”

Sound

In some areas, buildings are so close together that sound is a major concern. Split ductless systems are recognized for their quiet operation because the outdoor unit is located outside the residence. In some cases, a ductless indoor unit may run at only 19 dBa — comparable to the sound of a desktop computer fan.

“Indoor units operate at nearly whisper-quiet sound levels,” said Kimmy Do, product specialist engineer, Daikin AC (Americas) Inc.

This low noise level is attributed to the isolation of the compressor from the other parts of the unit, and a ductless unit’s ability to cushion very well against vibration.

Publication date: 04/23/2012