Important Considerations: Critical Areas Where NOT to Install a Mini Split

Do not install a mini split unit in locations with obstructed airflow, direct sun exposure, excess heat sources, unstable ground, improper height or space considerations. Doing so will undermine performance and efficiency. Installing a mini split system in your home or office can provide efficient heating and cooling comfort. But improper placement can undermine performance, efficiency, and your investment. This guide will highlight key mistakes to avoid when positioning both the outdoor and indoor mini split units. Following our tips will ensure your system runs at peak operation for years to come.

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Critical Areas: Where NOT to Install a Mini Split

Critical Areas: Where NOT to Install a Mini Split

Do not install a mini split unit in locations with obstructed airflow, direct sun exposure, excess heat sources, unstable ground, improper height or space considerations.

What Are Mini Splits?


Before detailing placement pitfalls, let’s review what mini splits are and why they're popular choices compared to central HVAC systems. Mini split systems consist of an outdoor compressor/condenser and one or more slim, wall-mounted indoor units installed in the spaces you want to heat or cool. They offer flexible “zone” climate control, high efficiency ratings up to 30 SEER, and quiet operation. Ductless design also allows installation in spaces without existing ductwork.


Unlike bulky central air conditioners or furnaces, mini split components have a compact footprint. But their positioning still impacts function. Improper placement can lead to:

  • Disrupted airflow and uneven temperatures
  • Higher electricity bills
  • Excess noise disruptions
  • Premature breakdowns


Fortunately, avoiding a few key mistakes can ensure your unit lives up to expectations.

Top Indoor Mini Split Placement Pitfalls


The indoor, wall-mounted unit should be centrally located in the space, ensuring it is at least one foot away from adjacent walls and obstacles. Ideally, it should be positioned at a height between 6 and 7 feet above the floor level. This strategic placement is crucial for enabling wide airflow distribution throughout the space, thereby avoiding the creation of uncomfortable drafts. Next, let's review 5 common mistakes to avoid when placing indoor units.


1. Blocking Airflow

Mini splits rely on optimized airflow to effectively circulate conditioned air throughout a space. However, disrupting this airflow can significantly impact the system's performance. Common examples of obstructions that impede airflow include placement behind curtains, doors, or bookshelves, areas with high foot traffic, corners crammed with furniture, and proximity to return air vents from adjoining spaces. To ensure optimal functioning, it's crucial to maintain at least 1 foot of clearance in front of and around all sides of the indoor unit. For ideal positioning, the unit should be centered on an interior wall and located away from windows, corners, and common walkways. This strategic placement facilitates maximum airflow and enhances overall comfort.


2. Exposure to Direct Sunlight

Direct sun exposure can have a significant impact on the efficiency of a mini split unit by falsely influencing the thermostat, leading to disrupted operation. The solar heat gain can cause the unit to cycle prematurely, increasing the risk of overworking the compressor. To prevent this, it is advisable to avoid placing units on southern walls that face prolonged sunlight. If options are limited, utilizing window treatments to block sun exposure can be an effective solution. Optimal locations for mini split units are on northern walls or in areas that experience minimal solar impact during peak daylight hours. This strategic placement ensures more efficient and reliable operation of the unit.


3. Mounting Too High or Low

Manufacturers typically recommend mounting indoor heads of mini-split systems at an elevation of 6-7 feet above floor level. This specific height is chosen because it enables wide airflow distribution, which is essential for effective heating and cooling. However, there are potential issues with mounting the units too high or too low. When mounted at positions exceeding 7 feet, the system struggles to push airflow down into the occupied areas, leading to uncomfortable drafts and the creation of stratified hot and cold spots. This can also result in inefficient cycling of the unit. On the other hand, mounting the unit lower than 5 feet can blast cold air too close to occupants, which is not only uncomfortable but also wastes energy. This is because hot air tends to accumulate along ceilings due to improper circulation. Therefore, it is crucial to verify that your room allows the unit to be mounted within the ideal 6 to 7 foot elevation before installation to ensure optimal performance and comfort.


4. Too Close to Electronics

Mini splits incorporate electromagnetic components that are susceptible to interference. When these units are mounted too close to antennas, transmitters, or other electronic devices, it can lead to the corruption of signals. This proximity can result in various issues such as disrupted TV, radio, WiFi, and cellular signals, increased equipment noise, and distorted picture quality. To prevent these problems, it is essential to maintain a clearance of at least 3-4 feet from electronic devices such as flat-screen TVs, radios, computers, medical devices, or security systems. This distance helps to minimize the risk of interference and ensures the smooth functioning of both the mini split system and the nearby electronic devices.


5. Unsupported Infrastructure

When mounting a mini-split unit on walls, it's crucial to ensure that the underlying structure meets engineering specifications to adequately support the unit's weight. This support should be distributed across multiple studs or solid blocking. Inadequate support can lead to several risks including loose mounting and misalignment, vibration noises, and potential falling hazards, which could be dangerous. It's not advisable to take chances with walls of questionable strength. Consulting a professional to assess the infrastructure prior to installation is essential for ensuring safety and proper operation of the unit. This step is key in preventing any structural or safety issues related to the installation of mini-split systems.

Key Outdoor Unit Placement Pitfalls

Mini split out door unit

The outdoor unit houses the noisy compressor, fan and refrigerant coils. While compact, its position also impacts function.


Avoid These Common Placement Mistakes:


1. Blocking Vital Airflow

Just like the indoor unit, ensuring ample clearance around the outdoor unit of a mini split system is essential for maintaining its long-term efficiency. Cramming the unit into tight spaces restricts airflow, leading to a significant decrease in overall performance. To avoid this, a minimum clearance of 24 inches should be maintained on all sides of the unit, with an additional 36 inches of clearance above it. This spacing is crucial for enabling critical airflow across the refrigerant coils. It's also important to avoid boxing the units in with dense bushes, trees, fences, adjacent walls and structures, or excessive snow piles during winter. Such obstructions can impede airflow and reduce the system's efficiency. Giving mini splits enough room to 'breathe' is vital for their optimal operation and longevity.


2. Exposing Unit to Excessive Heat Sources

Positioning mini split systems near hot exhaust vents, chimneys, or areas with reflected heat from walls or radiation from compressors can be detrimental, leading to a shortened lifespan and reduced efficiency of the system. To ensure optimal performance, it is important to avoid installing the unit within 3 feet of dryer vents and stove hoods, and at least 5 feet away from furnace exhausts and chimneys. The reason for this is that hot air and emissions can directly heat the coils of the unit, forcing it to work harder to remove heat. As a better alternative, choosing cooler, shaded locations such as north-facing walls or areas under eave overhangs is recommended. If direct sun exposure is unavoidable, consider using awnings to provide necessary shade. Such strategic placement can significantly enhance the efficiency and longevity of the mini split system.


3. Mounting on Unstable Ground

Outdoor units of mini split systems, containing heavy compressors and circulating refrigerant, place considerable weight on their bases. Mounting these units on uneven ground or surfaces, such as soft soil, presents several risks including tilting and misalignment, collapsing into the ground, and dislodgement of refrigerant lines. To prevent these issues, it is crucial to ensure that the unit sits on a stable, level concrete pad, particularly if ground mounting. It is often advisable to pay contractors to create a proper foundation to support this weight. When mounting on structures, only choose locations capable of supporting the equipment’s weight, such as exterior concrete or brick walls, or sturdy rooftop curbs or frames. It is important to avoid wooden decks or aged brick/stone mortar, as these may not be able to handle the added load. If not properly supported, vibrations from the unit can accelerate deterioration, undermine stability, and ultimately shorten the service life of the system.


4. Running Lines Too Far

The efficiency of a mini split system degrades with the increased distance between the interior heads and the outdoor compressor. Excessive lengths of refrigerant lines put a strain on the system's capacity, as it has to work harder to circulate refrigerant between components. Manufacturers typically recommend keeping refrigerant line runs limited to 15-25 feet for systems ranging from 9,000 to 18,000 BTU and 25-50 feet for larger capacity units. Exceeding 50 feet in length can lead to several issues, including increased wear on the compressor, higher electricity costs, noisy operation, and potential refrigerant leaks. In large homes where the distance exceeds these length thresholds, consider adding another outdoor unit to service the distant zones. This approach can significantly lighten the load on the system, leading to better overall efficiency and reduced strain on the components.

Let Our Experts Optimize Your Mini Split Placement

While mini splits offer flexible installation, positioning missteps undermine performance gains. By avoiding common indoor and outdoor unit placement pitfalls, your system operates efficiently for years while maintaining comfort. Still have questions? Contact our team of certified experts for a free consultation. We assess your property, usage and needs to determine optimal mini split placement tailored to your spaces. Benefit from a design maximizing comfort and energy savings for the long run. Reach out today to get started!

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