A ductless mini-split compressor on the external wall of a home

Ductless mini-split heat pumps can provide both heating and cooling for your home. In addition, they are very efficient, offering significant savings on your electricity bills and reducing your carbon footprint.

Many people in the US are familiar with central air HVAC systems that blow conditioned air into living areas via vents and registers. However, when it comes to ductless mini-split heat pumps, there is confusion about how these systems operate and how they are installed.

Those are precisely the type of questions that we like to answer.

Ductless mini-split heat pumps consist of an outdoor heat pump connected via refrigerant lines and electrical cables to an indoor air handler or condenser unit. 

Mini-splits can be installed in various ways, using a range of options available for both outside units and inside air handlers. Please keep reading to find out the different installation options and which one is right for you.

Can Mini-Split Heat Pumps Be Installed on a Wall?

Both a mini-split’s air handler and compressor can be installed on a wall to make the best use of space. If you want to mount the outdoor unit on the back wall of your home because it looks better there or at ground level along the side in a more discreet location, you can, without agonizing over how much sun it will get.

Where Should a Mini-Split Heat Pump Be Installed?

First, let’s bust a myth that could affect where you install your mini-split.

There are two main elements to a ductless mini-split system. These are the indoor air handler and the heat pump unit, which sits outside.

A common myth you might have come across is that AC condenser units (and heat pumps running in cooling mode) benefit from being located away from direct sunlight.

The tale goes that it’s better to install an outdoor mini-split heat pump unit away from direct sunlight because direct sunshine would make it work harder to keep your home cool during the summer—this is a complete myth.

The fan draws in large volumes of air from the surrounding area, perhaps moving 1,700 cubic feet every minute. So, the solar gain experienced by any air standing in and around the unit is quickly wiped out by ambient air rushing in and displacing it when the fan kicks in.

The condesner unit of a ductless mini-split next to an air conditioner outside a home

Also, the tremendous amount of heat rejected by the outdoor unit when in cooling mode means that solar gain effects would be negligible.

The same applies if you live in a cold part of the country and will only occasionally use your system for cooling, running it in heating mode for most of the year. Any sunshine on the unit won’t help make it more efficient for heating either.

In the sun or not, it makes no difference. This knowledge will help you to avoid unnecessarily restricting your installation options to the elevation of your house that gets the most, or the least, sunlight.

Options for Installing Your Mini-Split Outdoor Unit

The two options you can choose from for installing the outdoor unit are wall-mounted or ground-mounted.

Wall-Mounted Mini-Splits

Sometimes the only option, e.g., for apartment blocks, a wall-mounted unit can help make the best use of space for houses with a limited area around their perimeter, such as in urban environments.

Vibration and noise can be an issue, although this depends on the type of construction of the wall and whether damping material is used with the mounting bracket.

Ground-Mounted Mini-Splits

This style is less likely to have vibration and noise issues causing nuisance and disruption. It must be away from plants or other obstructions to ensure good airflow.

However, ground-mounted units can be susceptible to snow build-up during winter in some locations, which needs to be shoveled away.

Two mini-split compressor units outside a home in snowy conditions

Selecting Where to Mount Your Air Handler

There are several options for installing your interior mini-split air handler (also called an evaporator or “head” unit). Which you decide to go with is largely down to personal preference.

It’s best to keep them away from TVs to avoid potential signal interference issues. You will also need to make sure that the airflow is not obstructed and can circulate freely throughout the room, or zone, to be heated or cooled.

You can run the refrigerant lines quite long distances around the home, so you have a lot of flexibility in choosing locations for your air handler. There is no need to have your head unit on the other side of the wall immediately opposite the outdoor unit.

A mini-split system's internal air component above two doors near the ceiling of the room

Typically, 25 feet is the standard length supplied with many units, but up to 50 feet can work well. Bear in mind that longer lines will impact efficiency, but that shouldn’t be an issue in most homes.

For more information about refrigerants, their cost, and how eco-friendly they are, check out our article on the topic here.

Options for Installing Your Air Handler

There are several types of internal air handlers, which allow flexibility in their placement.

The main choices for air handler installation include:

  • Ceiling cassette – installed flush with the ceiling. This style is very unobtrusive.
A ceiling cassette mini-split head unit installed in a ceiling under construction
  • Floor standing units – installed on the floor up against a wall. These are useful if it is impossible to mount a unit on the wall.
  • Wall-mounted – installed high up on a wall, wall-mounted units are the most popular type of head unit. They keep the condenser out of the way and tend to be the cheapest option.

Tips for Wall-Mounted Units

  • A wall-mounted air handler unit must be installed high up on the wall, which helps with air distribution around the room.
  • Allow at least two inches of accessible space above the unit to allow for servicing and maintenance.
  • Mini-split heads must be installed on a vertical wall. Sloping walls are unsuitable.
A homeowner on a couch adjusts the setting of his mini-split using a remote control

Final Thoughts on Mini-Split Wall-Mounted Units

Ductless mini-split heat pumps are excellent for providing efficient heating and cooling in your home. Despite the widespread myth about the effect sunlight can have on their operation, placing them in direct sunlight has no bearing on their efficiency.

The outdoor units can be installed on the ground or mounted at any elevation on an exterior wall. Internal head units can be installed anywhere inside the house, although you might reduce efficiency if they are installed a very long way from the outdoor unit.

Wall-mounted air handlers are the most common and usually the cheapest head unit for use with a ductless mini-split.

If you would like to know more about the likely cost of a mini-split heat pump, why not read our article about it here?

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