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Ductless System Types and Mounting Options

Ductless systems offer home and business owners energy efficient heating and cooling solutions that optimize the comfort experience and help maintain healthful indoor air quality. Moreover, where installing or extending forced air ducted systems requires obtrusive space accommodations, ductless systems offer a plethora of customizable sizing, design and mounting options that can conform to practically any remodel, retrofit, space conditioning and new construction.

Discover the multitude of ductless system types and mounting options afforded by Mitsubishi Electric single-, multi- and flex-zoned and modular ductless configurations, and how going ductless affords you the luxury of placing a premium on aesthetics, comfort and energy savings for your Virginia home or business.

Ductless System Basics

The first ductless systems were developed in the 1970s by Mitsubishi Electric in an effort to meet the high demand for practical air conditioning in homes and businesses with limited spaces. Converting a space-consuming central system into a compact ductless air conditioning system earned immediate approval, and Mitsubishi has been a leader in ductless and HVAC innovation through four decades and keeps getting better.

The advantages of going ductless in lieu of installing or extending ducts or opting for unsightly and security risk window units are numerous. With the power of inverter-driven technology, high efficiency refrigerant and computerized super-heat/cool sensor and monitoring systems, ductless systems provide ample heating and cooling when outdoor temperature extremes dip into frigid single digits or climb to sweltering and sticky triple digits.

The basic design and components of any ductless configuration includes the following:

  • The outside unit houses the compressor, condenser coil, electronics and fan.
  • The indoor air-handling units (AHUs) contain the evaporator coil, a direct-drive fan and air filtration components, which may include an optional antibacterial and allergen filter and a deodorizing filter (essentially providing an air purification system for each zone).
  • A thin conduit connects the outside unit to up to eight AHUs. The conduit is routed through inconspicuous areas of the home (walls, attic and crawl spaces).

The Classic Ductless Mini Split

The classic ductless mini split was first developed as a cooling-specific ductless unit. The mounting options for the outside unit and indoor AHU was limited in distance of 10 to 15 feet from the technology of the time for the air exchange components (outside condenser, indoor evaporator, refrigerant lines and refrigerant).

Today, the ductless mini split is available as a heat pump for heating and cooling or as a cooling-specific system, and the mini split may extend well over 100 feet from the outside unit to the AHU inside the home or business. Single-zoned ductless systems are ideal for the following applications.

  • Conditioning retrofitted spaces inside the home, such as an attic or basement conversion, is a ductless mini split specialty.
  • For many homeowners, a ductless single-zoned heating and cooling system installed for an existing room, such as a home office or a room that is difficult to keep comfortable, makes better sense than installing a window unit or undertaking the expense and inconvenience of extending cumbersome ductwork.
  • If you need heating and cooling to convert a garage to a comfortable workshop, or for heating and cooling an outbuilding, single-zoned ductless systems fit the bill discreetly and efficiently.

Multi-Zone Ductless System

A multi-zone ductless configuration consists of two or more AHUs that connect to one outside unit. With the Mitsubishi Electric exclusive two-piping system, a multi-zone configuration is ideal for larger homes with significant heat gain/loss properties from room to room and floor to floor.

A two-piping multi-zone ductless system allows you to simultaneously heat and cool different zones (AHUs) inside the home at the same time. These are some of the uses of a multi-zone configuration.

  • Perhaps your home improvement project calls for heating and cooling multiple rooms and open areas, such as upstairs bedrooms that are difficult to keep comfortable within the desired energy budget. You may heat and cool these zones separately from one another and separately from the rest of the other levels in the household.
  • Some rooms in the home may need individual heating and cooling settings, such as home offices, rooms with elderly or young occupants, or a sun room.
  • Temperatures from one floor to the next can vary by as much as 10 to 15 degrees, and room temperatures may vary even more with differences in heat gain/loss properties of sun-facing rooms and shaded rooms that don’t receive much sunlight.
  • Multi-zone systems can keep rooms comfortable wherever they may be located inside the home. For instance, one occupant in an upstairs bedroom or bonus room may need the cooling cycle while another occupant in a retrofitted basement may need the heating cycle.

Flex-Zoned Configuration

A flex-zoned mounting option is a multi-zone ductless system that utilizes multiple single-zone air-handlers which condition two spaces each via short duct runs. This type of ductless configuration is useful for the following applications.

  • You may provide ample heating and cooling with one AHU for a large master bedroom, adjoining bathroom and walk-in closet.
  • A flex-zoned system may provide heating and cooling for four rooms with similar pairs of heat gain/loss properties, such as two sun-facing rooms conditioned with one AHU and two shaded rooms conditioned with a second AHU, and both AHUs are connected to the same outside unit.
  • Large rooms and open areas may utilize the slim duct installation, too, with the air supply grill and air return grill at opposite ends of the space.

Modular Configuration

If you are designing a new energy efficient home, or if you are undertaking a commercial remodeling project with a substantial amount of square footage to condition, a modular configuration offers practically an endless number of heated and cooled zones by installing two or more outside units and up to eight AHUs for each.

When you consider the Mitsubishi Electric optional two-piping system and the design freedom of flex-zones, you can see the multitude of possibilities for an energy-efficient heating and cooling solution that is customizable in size (BTUs and installation), and enjoy total indoor environmental control from one zone to the next.

With a modular configuration, as well as any mini- and multi-zoned ductless system, each AHU may and should be sized specifically for its zone. This maximizes comfort and energy efficiency, and helps lower the installation costs of your ductless system by preventing the purchase of over-sized AHUs. A Mitsubishi Electric Contractor is licensed and trained to size, install and service your new ductless system correctly for best results.

AHU Mounting Options

Multiple installation and mounting options for the indoor AHUs are made possible by routing the thin conduit or a two-pipe system through concealed spaces, such as inside walls, crawl space and attic space. These are some examples:

  • Universal mounting -- The Mitsubishi Electric Universal mounting option is a no-fuss solution that places a sleek AHU either high on the wall out of foot traffic, low on a wall (with clearance for a vacuum), floor-mounted console or a ceiling mount. Optional airflow enhancements assist floor consoles and ceiling-mounted AHUs to optimize comfort depending on heating or cooling cycle. The Universal mounting option also allows for easier access to the air filtration components.
  • Ceiling cassette -- The ceiling cassette mounting option has the aesthetics of a central system, with the supply grill (and return grill in slim duct flex-zoned configurations) installed flush to a drop ceiling or recessed into a ceiling.
  • Slim duct -- A slim duct installation utilizes space above the ceiling or inside the floor or wall to conceal the AHU. A slim duct run connects to an air supply and air return grill for increased air circulation through the zone. AHUs with self-cleaning air filtration components are recommended for these mounting types.

Mounting Options For the Outside Unit

The outside unit of any ductless system offers multiple mounting options to suit your needs. Whereas a large conventional central system requires significant space, which often takes precedence over exterior-design considerations, the outside unit of ductless systems offers a small footprint and less fuss. The only requirements are allowing free airflow to the top and sides of the unit, and perhaps protecting the unit from snow accumulation.

  • Concrete -- The outside unit may be mounted to a small concrete slab practically anywhere the conduit may reach the target zones. The unit may be strategically located among landscaping for better aesthetics.
  • Wall-mounted brackets -- Most ductless systems are compact and light enough to be safely mounted to the home’s exterior wall. This type of mounting is useful for shorter conduit runs to boost energy efficiency (efficiency tapers with longer conduit lengths).
  • Roof-top -- Flat roofs and low-slope roofs may accommodate the outside unit nicely for shorter conduit lengths to upper-floor heating and cooling retrofits, new additions and even a roof-top greenhouse.

Four decades later, Mitsubishi Electric ductless systems are more popular and better than ever, and continue to be a driving force for innovation in the HVAC industry. For more details about ductless system types, mounting options and designing and sizing AHUs for your home improvement project or new energy efficient Virginia home, contact us to find a Mitsubishi Electric Contractor in your area.

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