Go Ductless This Winter!

Go Ductless This Winter!

One of the latest and most popular innovations in heating and cooling your home not only saves energy, but is compact, cheaper to install and can be set up without tearing down walls.

Ductless heating and cooling systems, also known as mini-splits and ductless heat pumps, are growing in popularity around the world because they are a highly efficient heating and cooling option for homes. They were introduced to this country just 30 years ago from Japan and have been growing in popularity ever since. According to Navigant Research, by 2020, ductless systems will account for nearly 30 percent of all energy-efficient HVAC systems revenue.

Mini-split systems don't require ducts, which is where many homes lose energy. In retrofits, it is much simpler and less expensive to install a ductless system than one that requires ripping out walls and ceilings to install ducts.

These systems are also small in size, cost less to install than traditional HVAC systems, and use a fraction of the energy, substantially reducing utility bills. Energy Star-qualified systems can reduce cooling and heating costs by 30 percent. Newer models are continuously coming on the market, that are increasingly efficient.

The perception has also been that mini-split systems do not work in colder climates. However, according to Mike Smith, senior marketing manager for residential products at Mitsubishi Electric , their hyper-heating mini-split ductless systems are suitable for anywhere in the United States. He says one model can heat or cool at full capacity* when it is down to 5 degrees Fahrenheit outdoors. According to Smith:

"Low ambient heating technology is on the rise, allowing ductless heat pumps to function in low ambient outdoor temperatures. This capability is significant for two reasons: It means that ductless zoning technology is a viable solution for residences across the country even in colder climates like the Midwest and New England where heat pumps were not previously considered the best option. Also, hyper-heating technology frequently eliminates the need for supplemental heating, making the ductless zoning system the only system needed for total comfort control. This saves installation time, and improves energy efficiency without relying on fossil fuels. "

Mini-split systems tend to cost more initially, but they pay for themselves over time in energy costs. Smith says:

"The price of an installation will vary greatly depending on the specifics of the home. For retrofits that lack ductwork (e.g. adding air conditioning to a hydronic system) or additions where the central system lacks adequate capacity, ductless systems often provide the lowest first cost and least disruption to the building and its occupants. In new construction, the initial equipment cost of a ductless system may be somewhat higher than conventional equipment, but total lifecycle cost savings justify the initial equipment cost. Because of the systems' high efficiencies, they often qualify for utility rebates, which can significantly offset the equipment first cost."

In the past, many homeowners were reluctant to use these systems because they didn't like the look of the interior units. However, the interior units can now be recessed in the ceiling or mounted near the floor so they are less apparent than the units installed on the upper wall. Check out some of these installations in the attached gallery.

Ductless Heating System
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Go Ductless This Winter!

There are three parts to a ductless HVAC system.

Diagram courtesy of Mitsubishi.

Mini-split ductless systems can be installed in the ceiling.

Photo courtesy of Mitsubishi.

Or they can be installed in a wall unit.

Photo courtesy of Mitsubishi.

A wall installation.

Photo courtesy of Mitsubishi.

Another wall installation.

Photo courtesy of Fijuitsu.

An interior unit close to the floor.

Photo courtesy of Fijuitsu.

These units have been commonly used around the world. This one is in the B-House in Japan.

Photo courtesy of Yoshikazu Shiraki and Hideo Nishiyama for Prefabulous World.

Here is a unit in a home in Israel.

Photo courtesy of Assaf Pinchuk for Prefabulous World.

And growing in popularity in the United States. This one is in the Everett House in Washington State.

Photo courtesy of Anthony Rich for Prefabulous World.


Mini-split ductless systems are composed of three main parts: An indoor air-handling unit, an outdoor compressor/condenser unit, and a remote control that operates the system. A smart phone or computer can also control some units.

Heat is transferred using refrigerant expansion and compression, in much the same way as a refrigerator works. During the colder months, heat pumps move heat from the cool outdoors into the warm house, and during the warmer months, heat pumps move heat from the cool house into the warm outdoors. They move heat rather than generate heat, so they can provide up to four times the amount of energy they consume.

Because these systems don't have ducts, they avoid some of the energy losses associated with central forced air heating and cooling systems, particularly when the ducts are in unconditioned spaces. One outdoor condensing unit can be used for up to eight indoor air handlers in different zones of the house, each controlled to meet the needs of certain rooms.

The number of heat pumps required will depend on the size of the home and how well insulated it is.

Each of the zones will have its own thermostat so only the occupied rooms can be conditioned, saving energy and money. Some units are self-correcting -- so they can increase or decrease output depending on the set temperature.

For further information about ductless heat pumps, see Energy.gov website. Some of the suppliers of ductless mini-splits are Mitsubishi , Fujitsu , Lennox and Trane.

* "Heating capacity" is an HVAC term meaning at what level the system is operating. 100% heating capacity means it's operating at its most efficient state. The system will still work below 5 degrees F but it won't be at full capacity, it will be operating less efficiently but it will still be operational.
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