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Ductless Systems - Clean, Quiet, Comfortable Heating and Cooling

While ductless systems for heating and cooling are now being widely accepted by American homeowners, the technology actually began long ago, as a response to U.S. air conditioners in a distant land. Until after World War II, Japan was a mostly non-air conditioned country. Influenced by the United States during the postwar era, however, the Japanese attempted to adopt American window air conditioners. However, these units quickly turned out to be impractical. Unlike this country, Japanese homes were spaced very close together and the bulky, 1950s technology didn’t fit well in these narrow confines. In addition, total square footage and individual rooms themselves were significantly smaller in Japanese homes. U.S. A/C units were so oversized for those dimensions that the units performed badly and wasted energy — a major drawback in a country where electricity costs were five times higher than here.

Japanese engineers at Mitsubishi Electric adapted the basic idea and, by 1954, refined it into the first generation of ductless systems — quiet, powerful units that cool individual rooms and spaces in homes in an energy-efficient manner without the drawbacks of ductwork. In 1968, Mitsubishi Electric began exporting ductless technology to Europe, where it quickly caught on. Now Mitsubishi ductless units are widely distributed throughout the U.S. Where no heating and cooling ductwork exists, or where extending existing ducts into a new addition or remodel is not financially feasible, ductless systems are the perfect answer to fill the need for cool comfort.

So What’s Wrong With Ducts?

In many central air and heating systems, ductwork is a perpetual weak link in the performance and efficiency of the system. Residential ductwork was often constructed inexpensively to cut building costs and, after a few years, it typically leaks conditioned air. In fact, the Department of Energy estimates that the average American home loses at least 20 percent of heated or cooled air through leaks in ductwork. Some state studies have found that as many as 75 percent of existing homes failed to meet current, stricter standards for duct leakage. In addition to the wasted money as cooled or heated air spills into the attic or crawl space of the home, return ductwork operates under negative pressure and may suck outside air into the system through leaks. Air from these zones may be contaminated with mold spores and other toxins, so overall household air quality is impacted, too.

The energy losses, not to mention the declines in interior comfort, present in ducted central systems are major limiting factors in overall efficiency. Because ductless systems lack this significant drawback, the energy losses are generally limited to less than 5 percent. That’s just one reason why ductless units are available with SEER (Seasonal Energy Efficiency Ratio) ratings of up to 26 in the cooling mode, while the average SEER for conventional central air today is just 18.

One Room at a Time

While a system that cools only single rooms or enclosed spaces may seem limited, most homeowners will admit that many rooms heated or cooled by a central system are unoccupied most of the time. These rooms are simply a waste of energy to condition on a continuous basis. Ductless technology allows you to target the cooling and heating to the rooms where it’s needed and deliver it in the most efficient way. Ductless units are specifically sized to the dimensions of the room and available in a wide range of BTU ratings.

What’s Involved in Ductless?

A ductless system is an example of beautifully simple technology, consisting of just three components:

  • An outdoor coil and compressor in a small cabinet
  • An indoor wall- or ceiling-mounted air handler with coil and blower
  • A small conduit that incorporates insulated tubes to convey refrigerant back and forth between indoor and outdoor components as well as a power wire to provide electricity 

The outdoor unit can generally be placed up to 50 feet away from the indoor components and thus can be situated in some unobtrusive spot behind the home. The indoor air handler is low-profile and mounts flat against the wall, or on the ceiling, extending only a few inches outward. The refrigerant conduit requires just a 3-inch hole in an exterior wall to install it in the house.

How Does It Work?

A ductless heating system is a heat pump— downsized and made more efficient for conditioning individual rooms — that provides both cooling in summer and heat in winter. In hot weather, the indoor coil inside the air handler absorbs heat from the room and transfers it to refrigerant circulating through the coil. The refrigerant flows through the conduit out to the outdoor unit where the heat energy is concentrated by the compressor, then into the outdoor coil where rapid condensation disperses the heat load into the outside air. In winter, the flow of refrigerant reverses and the coils exchange functions. The outdoor coil extracts latent heat energy out of the air, intensifies it through the compressor cycle, then the refrigerant carries the heat energy inside where it is dispersed by the indoor coil and blower to warm the room.

Additional Pluses

Engineering advancements specific to ductless systems provide other advantages not available on conventional central air conditioners or whole-house heat pumps.

Inverter technology

The compressor in a conventional A/C or heat pump unit is a very high consumer of electricity.  Standard compressors operate at only one speed and control output by turning on and off repeatedly during operation. This continuous alternation between zero output and maximum output wastes energy and adds wear and tear to the compressor, the most expensive component in the system. A ductless heat pump uses inverter technology to modify compressor output to fit the heating or cooling load of the moment. While the compressor runs most of the time, it is usually in a reduced-output mode that consumes less energy than a conventional on/off compressor. It also reduces component wear and provides more consistent comfort, without the temperature surges and fades that characterize on/off compressor cycles.

Fewer decibels

Window air conditioning units, often considered as an alternative to central A/C, emit indoor noise levels as high as 60 decibels. In central air conditioners, the outside unit containing the heavy-duty compressor and fan is often very loud (ask your neighbors) and indoors, the sounds of air rushing and rumbling through ducts can be another disruption to interior peace and quiet. Ductless systems on the other hand produce less than 50 decibels indoors — since the decibel rating system is not linear, a 50-decibel noise is actually half as loud as 60 decibels. In addition, the inverter technology incorporated in the outdoor compressor operates at a reduced output most of the time for less outside sound, too. Since ducts aren’t a factor, noise from airflow in ductwork is totally eliminated.

Healthier air quality

Whatever floats around in your indoor air eventually ends up deposited inside your ductwork. Over the years, ducts can become breeding grounds for toxic mold and bacteria or just a storehouse of common, allergy-causing dirt and dust. Ductless systems not only lack the ducts that gather airborne impurities, they incorporate advanced filtration specifically designed to safeguard indoor air quality. Some models are capable of removing particulates down to the size of bacteria and viruses.

Easy installation

Installing or extending ductwork in a home can be a traumatic procedure that disrupts normal life in the household for many days. Ductless systems generally require only a single hole in an exterior wall to route the conduit, then an easy mounting procedure for the indoor air handler and outdoor unit. A ductless system to heat and cool a single room can be easily installed by a two-person team in just one day.

For ductless air conditioning sales and service in Virginia, contact us to find a Mitsubishi Electric Contractor in your area.

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