It’s a question a lot of people ask – even those who’ve had mini-splits before. Of course, we all know the indoor unit traditionally goes on the wall – unless otherwise specified. However, you’re usually left wondering what’s best for you when it comes to the outdoor unit. Does it go on the wall too, or do you set it on the ground?
The short answer is – both options are applicable. For example, some people prefer wall installations because a raised installation protects the condenser unit from adversities such as floods. However, you can also raise the ground-installed condenser unit, right?
In the end, it’s mostly about choice. As long as you choose the right location with sufficient clearance and provide a sound base to bear the weight and vibration of the unit, everything should be fine.
However, if you still can’t decide, we recommend comparing the pros and cons of the two options.
Wall Installation Pros and Cons
Installing the outdoor condenser means that you screw an outdoor bracket to the wall and fit the condenser unit to the bracket. Typically, you’re required need to install it on the same wall as the indoor air handler.
However, you can also install it on any wall as long as it’s outside the house and in favorable conditions. This is especially true if working with ceiling cassette air handlers installed on the ceiling rather than a particular wall.
Wall installations can be slightly intimidating. However, the option comes with several valuable advantages over ground installation. These include;
Proximity to the air handler
Mini-split air conditioners are most efficient if the distance between the outdoor condenser and the indoor air handler is minimal. A short distance between the two components allows the refrigerant to cycle between the two parts faster, reducing energy loss. If the distance is longer, there’s a greater surface area for energy loss.
Installing the outdoor unit and indoor air handler on different sides of the same wall can reduce the distance between the two to as little as a meter or two.
Plenty of clearance at the bottom
You’ve likely read elsewhere that clearance is of great importance when deciding where to locate the outdoor unit. It would help if you had plenty of space all around the condenser unit for the free flow of air. Otherwise, you may have airflow constriction or blockage issues that may result in ice-formation inside or outside the house.
Wall installations offer the best bottom clearance. Air can flow around the bottom without any impediments. It reduces the risk of overheating.
Protection from floods and ground-level impediments
Finally, outdoor air conditioner units are sensitive appliances that require a lot of care. Exposure to dust and other dirt elements creates a high risk of air blockage and internal damage. Floods and flush water can also enter the unit if it’s on the ground, creating all kinds of problems.
Installing the unit at a raised position on the wall protects it from ground-level elements such as floods, fallen tree branches, and overgrown grass impeding airflow into and out of the unit.
Unfortunately, wall installations come with a few drawbacks that you need to keep in mind when choosing.
Limited airflow at the back
Wall installations are such that the outdoor condenser is at most one foot away from the wall. The distance to the wall is much shorter in most installations. So, although the unit gets plenty of airflow at the bottom, there’s little room for the same at the back.
Most manufacturers recommend placing the outdoor unit at least 15 centimeters (0.5 feet) away from the wall to mitigate this problem. However, it still limits the flow of air to a degree.
Weight support issues
This second problem is more common in bigger mini-split systems. Although the smaller mini-splits weigh only a few dozen pounds, larger models can weigh over 100 pounds. Some even weigh 200+ pounds.
This becomes a significant issue because both the wall brackets and the wall itself must be strong enough to support the massive weight. Otherwise, the condenser unit might come crashing down. It may even bring a portion of the wall with it, necessitating costly repairs.
Ground Installation Pros and Cons
Ground installation is the better of the two options, particularly for heavier (larger) mini-split systems, though it also comes with a few potential downsides.
Installing the outdoor unit comes with two main advantages – excellent weight support, plenty of clearance all around, and reduced noise.
No weight/support issues
A solid ground can support just about any weight. It doesn’t matter if the AC is 50 pounds or 200 pounds. You don’t have to worry about the massive weight of your large air conditioner bringing down a portion of your walls.
Also, you don’t have to live every second worrying about the supporting brackets potentially crashing under the weight of the AC.
Plenty of clearance all round
This is another important reason to choose ground installation over wall installations. In an ideal scenario, you want a three-foot clearance all around the outdoor condenser for unimpeded airflow. However, wall installations only allow a 30cm clearance at best.
A ground installation allows you to locate the unit as far from the house as possible. You also have greater flexibility in selecting the ideal location for the unit, away from obstructions such as trees and shrubs.
A longer distance between the outdoor unit and the wall can also mitigate noise issues. When the AC is located too close to the wall, the echoes are louder and more impactful. The sound also reaches the people inside the house faster. Above all, the vibrations caused by a running compressor unit can be painfully annoying.
Placing the AC slightly further from the wall can help reduce the audible noise and minimize the effects of vibration.
Unfortunately, ground-installed outdoor condenser units aren’t perfect either. The following are two common challenges you’ll have to deal with;
Ground clearance issues
Although you’re allowed to place the outdoor unit directly on a concrete surface, issues such as runoff water and floods come to mind. For example, if the unit sits directly in the path of oncoming floods and running water, some of the water might enter the unit, causing problems. Ducts and dirt particles can also more easily enter the unit from the ground than a raised position on the wall.
Most HVAC technicians mitigate this problem by designing a solid platform to help raise the AC at least a few inches off the ground. But it must still be a stable area that’s not prone to sinking.
Distance from the air handler
The location flexibility that ground installation affords can also create a new problem – keeping the distance between the indoor and outdoor units to a minimum. Finding the perfect spot for your compressor unit, you may find that the distance between the indoor and outdoor units is larger than ideal.
You want to keep the two components as close as possible for maximum energy efficiency. Also, protecting the refrigerant lines and electric cables becomes a little more complicated if the condenser is far from the house.
The “perfect” location for mini split outdoor unit placement depends on many factors, including noise issues, the strength of your wall, the size of the AC, and energy efficiency considerations.
The most important thing is identifying a location where the unit is safe and protected from weather and other elements without losing valuable energy efficiency. Also, make sure it doesn’t impede your movement around the home.