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How Does Ductless Air Conditioning Work

Ductless split systems are an attractive alternative to noisy window units, unreliable PTACs and inefficient central HVAC systems. While U.S. consumers are just beginning to recognize the advantages of ductless air conditioning, the technology has been used for many years in developed countries around the world.

A Basic Explanation of Ductless Operation

Potential buyers often wonder: how does ductless air conditioning work?

The essential operation of a ductless system is very similar to a conventional split system air conditioner. When the thermostat calls for cooling, the compressor engages and converts low-pressure gas into a high-pressure gas. As the gas moves through the condensing coil, heat energy is dispersed into the outdoor environment by the action of the condensing fan.

The refrigerant is transformed into a high pressure liquid until it undergoes another change through a thermal expansion valve at the evaporator coil. Heat from the living area is extracted by the low-pressure refrigerant, and the cooler air is distributed back into the building. The low-pressure gas moves into the compressor, and the cycle begins once again until the thermostat call is satisfied.

There are two primary components included in a ductless installation:

The Outdoor Unit

The outdoor condensing unit in a ductless system is very similar to a conventional condensing unit in terms of construction and operation. There are three primary elements that work in tandem to accommodate the heat transfer process.

  • Compressor: The compressor is the most critical component in any air conditioning system. It is also the most costly part to replace. In a ductless system, the compressor often features a regulator that controls the speed of operation to provide exceptional efficiency that is unavailable in conventional systems.
  • Condensing Coil: The condensing coil is a corrugated structure made of aluminum. High-pressure gas is forced through copper tubing, and the heat energy is dissipated through aluminum fins.
  • Fan: The fan pulls ambient air through the condensing coil and redistributes the accumulated heat outdoors.

The Indoor Unit

The advantages of a ductless split system are tied directly to the unique construction of the indoor unit.

So, how do ductless air conditioners work?

Conventional central AC systems include a single air handler, evaporator coil and blower, which is typically located in an equipment closet or garage. An intricate duct network is required to establish a pathway for the conditioned air to travel from the air handler to the different rooms in the building. Ductwork is a significant source of noise and inefficiency in a conventional HVAC system.

By contrast, ductless indoor units include an evaporator coil and fan in a single enclosure. Every air handler provides point-of-use air conditioning whatever room it is installed. Attractive cabinets are available in duct mount, ceiling cassette and wall mount varieties.

A single indoor unit is most appropriate for additions and spot cooling, but multiple air handlers can be matched with one condenser to provide true zoning throughout a building. The convenience and versatility of ductless air conditioning completely eliminates the need for ductwork, registers and the associated maintenance requirement.

When comparison shopping for ductless ac vs. central ac vs. window unit, ductless split systems will prove to be more efficient, quieter and provide superior levels of comfort.

Mini-Split versus Multi-Split

How do ductless air conditioners work in multi-room zoning?

Ductless split systems offer heating and cooling solutions for a variety of challenging applications. Systems are configured around two basic platforms.

Mini-Split: A mini-split is designed for single zone cooling and includes one indoor air handler and one outdoor condensing unit. This configuration is particularly appropriate for cooling a room that has a minimal load requirement. Mini-splits can also be used in combination to provide heating and cooling for different rooms, assuming there is adequate space to set multiple condensing units.

Each indoor fan coil has a separate remote control. If there is a failure in one system, the remaining units will continue working to cool the unaffected rooms in the building.

Multi-Split: A multi-split system provides the ultimate in comfort, efficiency and climate control for complete zoning and whole-house applications. Mitsubishi manufactures systems that can accommodate up to eight indoor units connected to one condenser for precise and targeted cooling and heating.

For true multi-split zoning, the condensing unit includes individual compressor circuits that are connected separate fan coil enclosures. Every zone is controlled by its own remote, so the temperature can be tailored to the individual preference of each occupant.

How Ductless heat Pumps Work

While in the cooling mode, a ductless heat pump functions in exactly the same manner as a mini-split air conditioner. Heat pumps include a reversing valve that allows the refrigerant to flow in the opposite direction when the unit is placed into the heating mode. A heat pump provides both cooling and heating from a single system.

Before installing a ductless heat pump, it is helpful to understand the limitations of the system in cold weather. Heat pumps perform most efficiently in mild climates where the outdoor temperature rarely reaches the freezing point. A qualified HVAC contractor can install an electric heat strip for supplemental heating purposes if necessary.

Where Ductless is Needed

Ductless heat pumps and air conditioners provide exceptional versatility and can be adapted to meet a variety of applications. Ductless systems are being used more often in new construction where the low profile of the equipment provides architects and engineers with unrestricted design flexibility.

An Air Conditioner That is Small Enough For:

  • Condos
  • Server Rooms
  • Garages
  • Attics
  • Basements
  • Buildings Requiring Supplemental Cooling

An Air Conditioner Quiet Enough For:

  • Bedrooms
  • Hospitals
  • Churches
  • Meeting Rooms
  • Recording Studios

An Air Conditioner Powerful Enough For:

  • Multi-Tenant Buildings
  • Office Buildings
  • Hotels
  • Data Centers
  • High Rise Buildings

High Efficiency Perfect for Everyone!

So, how much does ductless AC cost? Qualified HVAC contractors can provide a complete breakdown of material and labor expenses, probable operating costs and potential savings when compared to a conventional system.

Ductless heat pumps and air conditioners offer enhanced comfort, low noise levels and exceptional efficiencies. Ductless systems with exclusive inverter technology have the highest SEER ratings of any available air conditioning product. Mitsubishi Electric Cooling and Heating invites you to learn more about the many advantages that a ductless split system can provide.