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Ductless HVAC Systems

Mother-in-law suites are private living areas that are part of an existing property. They can be within the main home, such as a finished basement or attic, or detached as a stand-alone structure. 

While mother-in-law suites usually feature at least a bedroom and bathroom, they may also feature other areas such as a kitchen or kitchenette and living area. Their primary purpose is to provide comfort and privacy for the tenant, whether a family member, visitor, or guest.

The utility logistics of a mother-in-law suite can sometimes be complicated, but choosing a ductless mini split heating and cooling system is always an easy choice. Read below to find out why ductless HVAC systems are perfect for mother-in-law suites, and then order yours from ComfortUp today!


Mini splits do not require the extensive ductwork of the central HVAC system. This provides clear advantages, as it leads to increased operating efficiency and lower energy consumption and bills. It also simplifies their installation process. 

Extending ductwork is costly and time-consuming, making it a less than ideal heating and cooling option for your in-home mother-in-law suite. It is also impossible to extend ductwork to a detached mother-in-law suite.

Fortunately, installing a mini split in your in-law suite addition is as easy as any other room in your house. While some mini split systems can be DIY installed by homeowners, we recommend hiring a professional technician for installation. Not only does this guarantee your system functions properly and efficiently, but it also ensures the warranty remains valid.

To prepare for your mini split installation, simply pick the location in the room, clean the area, and let the technician handle the rest! Mini splits also have very simple maintenance processes, relative to other HVAC systems. Regular maintenance, such as wiping the filters, coils, and condensers clean in addition to annual deep cleanings, helps keep your system operating efficiently for years to come!

bedroom air conditioner


Mini split air conditioning systems are available in single and multi-zone systems. A single-zone system features one outdoor condenser connected to one indoor unit, while a multi-zone system features multiple indoor air conditioners connected to the same outdoor unit. Depending on your suite’s specific layout and HVAC needs, either configuration is an excellent option.

If your suite is detached from the rest of your home, such as a dedicated in-law apartment, it will require its own single or multi-zone system, depending on the number of rooms within the suite. A single-zone will work if your suite is a single room or open area, but you will require a multi-zone system if you have multiple areas to heat and cool, such as a bedroom and kitchen.

If your suite is within your home, such as a basement or attic, you have several different options, depending on the size of your suite and your home’s existing HVAC system. If you have a multi-zone system already in your home, you may be able to add additional indoor unit(s) for your suite. You could also purchase a single or multi-zone system exclusively for your suite. Your HVAC system cost will be related to brand, make, and model in addition to the number of units required.

Mini split systems are designed for rooms of specific sizes, so be sure to know the measurements of your mother-in-law suite before purchasing. An improperly sized mini split does not operate anywhere close to peak efficiency, which leads to higher energy costs and an unpleasant indoor environment.


To find the ideal mini split size for your in-law apartment, follow the Department of Energy’s rule for estimating the ideal air conditioning capacity in a room or zone: 20 BTUs per square foot.

According to statistics collected by, the average size of an in-law suite ranges from 300 to 1,000 ft², meaning that the appropriate air conditioning capacity for this room ranges from 9,000 BTU to 20,000 BTU.

Consider the room or apartment’s other factors, such as the level of insulation, the local climate, the humidity levels, and the level of exposure to sunlight. 

  • Local climate: For example, if the house is located in a region with hot summers averaging temperatures of 90°F or more, add 30% to your sizing needs. If your geographic area has cold winters, consider getting a heatpump capable of both heating and cooling.
  • Exposure to sunlight and natural heat: If one of the rooms in the in-law apartment features large windows letting in sunlight and heat over long periods, add 10% to the amount of BTUs to compensate for the heat gain. In contrast, if the windows are in a shaded area or face away from the sun, remove 10%.
  • Insulation level: If your in-law apartment features standard insulation levels, you don’t need to make any changes. If the insulation is brand-new, reinforced spray foam, or recently redone as part of a home renovation project, decrease your BTU needs by 10%.
  • Humidity levels: If you intend to install a mini split inside the suite’s bathroom unit, you must consider the increased humidity levels when choosing your system’s size. An indoor unit for a bathroom should have 20% more capacity than a standard room of the same square footage.


The traditional purpose of an in-law suite is similar to that of a guest house or bedroom: to provide a separate temporary or permanent living space and sleeping area for elderly family members. The best way to ensure they are as comfortable as possible is to use a mini split AC system. 

One of the primary advantages of a multi-zone mini split system is the ability to control each zone independently. Even if you dedicate one of your zones to the mother-in-law suite, changing the temperature and the settings in the suite will not change the temperature in the other rooms. 

This flexibility is advantageous if your guests or family members have specific temperature requirements that differ from the house’s primary bedroom, living room, or any other zone.

Additionally, most multi-zone systems package each indoor unit with a corresponding remote control, letting family members change the AC settings comfortably and from anywhere in the room.


Mini splits do more than just create the perfect indoor climate; they also create a healthier environment. Inside each indoor unit is a filter that removes harmful airborne contaminants during operation. 

Your mini split can filter out dust, dirt, debris, dander, and more as it heats or cools the area! It also removes airborne moisture to prevent mold and mildew growth.

Purifying the indoor air with a mini split has short- and long-term health benefits. It decreases sinus and respiratory irritation while the decreased exposure to harmful elements also helps reduce your chance of disease over time. A mini split ensures that anyone who inhabits your mother-in-law suite is in a healthy and pleasant environment.

ductless ac


ComfortUp proudly sells mini split systems and accessories from the industry’s most trusted brands such as Mitsubishi, GREE, LG, Panasonic, Boreal, and more. We’re here to answer any questions, so give us a call at 1-855-337-0001 or contact us online today!

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