A homeowner peers under the opening of his garage door and smiles as he opens it from inside

Garage workspaces are common in many homes throughout the US but it can be difficult to enjoy your garage space in peak summer and winter temperatures.

Mini-splits are known for their efficiency in heating and cooling localized areas. Would one of these units be good for your garage?

As with all HVAC options, your home setup, climate, budget, and heating and cooling needs will factor into your decision.

Is Using a Mini Split in Your Garage a Good Idea? 

In most cases, mini-splits are a good choice for a garage. They can provide both heating and cooling with a single system and don’t require ductwork, making installation relatively simple.

Most mini split installs can be done within a day and you will be enjoying a temperature-controlled garage in no time. However, these units aren’t cheap.

Because of their energy efficiency, they have low operating costs but the upfront installation cost can be high.

The brand, model, your geographic location, and the HVAC company you use all affect what you’ll pay for the installion.

Mini-Splits vs Traditional Garage Heaters

The biggest benefit of a mini split for garage use is their ability to both heat and cool. 

Garage heaters are simply furnaces that do not use ductwork but rather a powerful fan to circulate warm air. They do not provide any cooling. If your garage space requires cooling, you will have to set up a separate AC system.

Alternatively, you could install a central HVAC system in your garage that can provide both heating and cooling. This system will need some type of ductwork to circulate air.

If the garage is unfinished, installing ductwork can be done, but it will be time-consuming and expensive. If your garage has low ceilings, you will lose a bit of headspace where the ducts are hung.

Ductless mini splits are popular choices because they do not require ductwork and can provide enough heat and cooling for the average-sized garage.

While expensive to install, they are still only half the price of a brand new central HVAC system (forced-air furnace and AC).

Despite being a fully electric system, they are integrated with their own smart technology to reduce energy costs and lower utility bills.  

They are extremely quiet when operating. So much so that you can barely hear them. If noise is a concern of yours, this is something to consider.

The outdoor compressor component of a ductless mini-split
Mini split units are ideal for homeowners looking for less installation costs.

What Size Mini Split Do You Need for a Garage?

Garages come in a multitude of sizes. But luckily, so do mini-splits.

This handy chart can determine how much heating and cooling power you require.

Size of Your Garage Heating and Cooling Required 
200 square feet3,000 to 5,000 BTUs
300 square feet4,500 to 7,500 BTUs
400 square feet6,000 to 10,000 BTUs
500 square feet7,500 to 12,500 BTUs
600 square feet9,000 to 15,000 BTUs
700 square feet10,500 to 17,500 BTUs
800 square feet12,000 to 20,000 BTUs
900 square feet13,500 to 22,500 BTUs
1,000 square feet15,000 to 25,000 BTUs

The above amount of heating and cooling power is presented as a range. How many BTUs your garage actually requires depends on the brand of mini split you buy and its SEER and HSPF rating.

The chart above also assumes that you’re using one indoor air-handling unit for the entire space. If you have an extremely large garage or a pole shed you are looking to heat or cool, you will likely need two or more air handlers.

These can be connected to the same outdoor unit but they will be able to provide more effective temperature control for large spaces.

A ductless mini-split in the corner of a room below the ceiling
There are two ratings you have to watch out for when buying a mini split.

What SEER and HSPF Ratings Should Your Mini Split Have?

Ductless mini-splits are lauded for their energy efficiency compared to traditional HVAC units like furnaces or air conditioners.

On average, mini-splits are 30% more energy-efficient and can be upwards of 50-60% in some cases.

To ensure your mini split is as energy-efficient as it gets, you should pay attention to both the SEER and HSPF as you shop around.

SEER Rating

SEER is short for the seasonal energy efficiency ratio.

SEER measures how much cooling output an air conditioner uses on an average day of cooling. To calculate the SEER, you divide that cooling output by how much electricity the mini-split needs.

A higher SEER rating means the unit is more energy-efficient, whereas a lower number indicates it is less efficient and could make for higher utility bills.

That being said, if you live in a very hot and humid climate, you will need an AC with a higher SEER rating than if you live in a cooler, dryer climate.

Mini splits have higher SEER ratings than most traditional AC systems, so finding an efficient unit for your climate should not be a problem.

HSPF Rating

SEER is the rating of how energy-efficient a mini split is while it’s cooling; there’s also a rating that determines the energy efficiency of a mini split in heating mode.

This is the heating seasonal performance factor or HSPF. 

HSPF compares the heat output ratio in BTUs versus the amount of electricity the mini split uses, calculated in watt-hours. You divide the two numbers like you would when calculating SEER.

The rating is pretty different, though. While a SEER of eight would be way too low, anything rated eight or above in the world of HSPF is considered very energy-efficient.

These units are usually eligible for a US Energy Tax Credit. Once a heat pump has an HSPF of 8.2 or over, it’s an Energy Star-approved appliance. 

The highest HSPF rating as of this writing is 10. As with SEER ratings, your mini split needn’t have an HSPF of 10, but you want the score to be at least an eight. 

Factors to Consider Before Installing a Mini Split in Your Garage

Local Climate and Temperature Extremes

Most mini-split heat pumps work best in moderate climates. If you live in a cold area (temperatures that reach below 0°F), you will need a model that can function at those temperatures.

Garage Construction and Insulation

Before installing any HVAC unit in your garage, make sure it is properly insulated or you will be wasting quite a bit of money heating and cooling air that escapes through the walls.

Foam insulation seems to work well in garage spaces but you can use whatever type of insulation you prefer. 

Sizing and Capacity

Ensure that the mini-split heat pump is properly sized for your garage. An undersized unit won’t provide adequate heating or cooling, while an oversized unit can lead to inefficiency by wasting energy.

Outdoor Unit Location

You must install the outdoor unit in a location with sufficient air circulation where it can disperse the heat freely. It should be away from water, direct sunlight, and at least two feet from structures.

If you live in a snowy climate, consider installing the outdoor unit on a bracket that mounts to the wall of your garage. Since the outdoor condenser runs during the winter in heating mode, it won’t be as susceptible to snow buildup if it is off the ground.

If you do choose to mount the condenser on the ground, be sure to remove any snow around it during the winter.

Indoor Unit Location

The indoor unit should be mounted high on the wall in a central location to provide the best air circulation. Make sure it is easy to access for filter cleaning and service.

Local Regulations and Codes

Check with your local building department or authorities to understand any zoning restrictions, building codes, or permits required for installing a mini-split heat pump in your garage.

Compliance with local regulations is essential to avoid legal issues down the road.

Source of Power

You need to have a circuit that is not underpowered for efficient operation. It’s recommended to install a dedicated circuit for your garage’s mini-split AC.

Cost and Efficiency

While mini-split heat pumps are energy-efficient, they have a higher upfront cost depending on the BTUs, equipment features, and tonnage of the zones.

Mini-split installations can cost anywhere between $2,000 and $14,500.

Warranty and Professional installation

Choose a reputable brand and ensure that the mini split heat pump has a warranty. Additionally, professional installation is crucial for proper performance and warranty coverage.

While these systems may seem easy to install, they should still be done by a professional HVAC company. 

A newer mini-split compressor outside the exterior of a home
Aside from ratings, you need to consider the general climate of your location for your mini-split to perform effectively.

Final Thoughts 

I’ve been working in the HVAC industry for 15+ years and mini splits are one of my top choices for heating and cooling garage spaces.

Unless you have a large, industrial building, a mini-split system is more than capable of providing adequate heating and cooling.

The biggest installation considerations are to adequately insulate your garage before installing the mini split and to ensure the mini split you choose is sized correctly for the space it services.

Have your mini split serviced by a professional every few years to ensure everything is working correctly and don’t forget to clean the filters in the indoor head unit. You will enjoy a comfortable garage for many years to come.

One Comment

  1. I’m considering installing a mini-split in my garage for my workshop, and this post has really helped me think through the pros and cons. The idea of having a more consistent temperature and humidity level is really appealing, especially since I work on projects that require specific conditions. I’m definitely going to do more research and see if it’s a good fit for my space.

Leave a Reply

Your email address will not be published. Required fields are marked *