Is a Mini Split Good for a Garage? (Heating & Cooling)


Most houses don’t have heating and cooling in the garage. However, many people are using their garage as a workshop. But, working in a hot or cold garage is no fun at all. So, I did some research about the garage to see if a mini split is good for it.

It turns out that a mini split air conditioner is an excellent choice for heating and cooling a garage. Mini splits are very efficient and they operate incredibly quiet. Mini splits are a space saver because they don’t require ducts and they are mounted up high on the wall. If you install it by yourself, a mini split is a very cost-effective heating and cooling solution for your garage.

Although they see people are using a mini split in their garage, some people still doubting that a mini split is applicable for them. Let’s look at how well a mini split work under different climates.

Can a Mini Split Heat and Cool a Garage Well?

Having a mini split in your garage will keep your garage cool in summer and toasty in winter. Mini splits are able to bring the temperature in your garage down to 75°F (24°C) when the outside temperature is at 95°F (35°C).

The outside temperature may drop to 32°F (0°C) in the winter. A standard mini split heat pump is able to keep up and maintain the temperature in your garage at 75°F (24°C). Keeping your garage warm and toasty. Most mini splits are able to cool effectively up to an outside temperature of 115°F (46°C).

If you are living in extremely cold states such as Alaska and North Dakota, the average temperature during winter may hover around 0°F (-18°C) or 10°F (-12°C) which is beyond the effective working temperature of a standard mini split. A standard mini split can lose half of its heating capacity when the outside temperature drops to 17°F (8°C).

Therefore, you’ll need a mini split that is designed to work in extremely cold weather conditions and this type of mini split is often called the arctic mini split or some other names depending on the manufacturer. You’ll have to check the operating temperature of the mini split in the manufacturer’s specification sheet to confirm.

If you have an arctic mini split, it is able to maintain your garage temperature at 75°F (24°C) even when the outside temperature is at 0°F (-18°C) and below.

Below are some of the arctic mini splits for extremely cold weather:

BrandModel SeriesAvailable Capacity (BTU)
SenvilleAura12k, 24k, 36k
PioneerDiamante9k, 12k, 18k, 24k, 36k
Air-ConBlue Series 312k, 18k, 24k
DaikinAurora9k, 12k, 15k, 18k, 24k

When the outside temperature drops below the freezing point of water, the mini split outdoor unit gradually freezes up, causing its performance to drop. But, the mini split will boost its heating power to accommodate that. You’ll hear a louder noise at the outdoor unit when it’s pushing the limit.

However, the mini split outdoor unit will eventually come to a point where it is no longer able to work with all the ice on its coil. Then, it’ll stop heating for a few minutes in order to perform defrosting. Afterward, it’ll go back to heating like normal.

Some mini splits stop working to defrost while some mini splits use an auxiliary heater to defrost. Mini splits that use an auxiliary heater to defrost are able to continue to provide heating without having to stop for a few minutes. Thus, they provide much better comfort but at the expense of higher electricity consumption.

If you ask me, I recommend the Daikin Aurora series mini split heat pump (click to view on Amazon) if you are living in a very cold place. Otherwise, a standard one that I would recommend to you is the Daikin 19 series mini split heat pump (click to view on Amazon). They are more expensive than other brands but their quality and performance are incomparable.

Daikin is a Japanese company with nearly 100 years of history. All they do is making the best air conditioners. I’ve been using Daikin mini splits for many years in my house and they never fail to deliver. Although my Daikin mini splits don’t heat cause I don’t need it, I’m confident in their built quality and performance. See more in my post about Daikin mini splits versus other brands.

Though arctic mini splits are able to work when the outside temperature is below 0°F (-18°C), they are running at about 50% efficiency only. The colder the outside temperature, the less efficient they are due to the frequent defrosting process.

Nevertheless, arctic mini splits usually stop working when the outside temperature drops beyond -13°F (-25°C) which is more than enough for most places in the United States.

How Much Does It Cost to Install a Mini Split in a Garage?

A standard mini split costs anywhere between $1000 and $1700 to purchase for an 18,000 BTU model which is most likely needed for a standard 2-car garage with about 360 square feet and non-insulated walls.

Many people install a mini split by themselves in their garage but if you need a professional to help, it’ll cost anywhere between $300 and $1500 to install depending on where you live. There are many factors affecting the cost of the installation such as location, where you want to install, do you need additional electrical work and etc.

How Many BTUs Needed for a Garage?

For a garage with uninsulated walls, I suggest using 50 BTU per square foot to calculate how many BTUs you need. Garages have more air leakages than standard rooms. Besides, they gain more heat from the roller shutter door. In addition, your cars are giving out heat when you just came back from outside.

Thus, I would not advise you to use online calculators because they are designed for standard insulated homes. Nevertheless, you can always seek local experts for advice but they’ll expect you to buy from them. Yeah, you can just don’t buy from them after they’ve given you the size but you know…it’s complicated.

Below is a guideline to how many BTUs needed for a garage:

Garage SizeUninsulated Wall & DoorInsulated Wall & Door
1 Car (~240 sqft)12,000 BTU9,000 BTU
2-Car (~360 sqft)18,000 BTU12,000 BTU
3-Car (~704 sqft)18,000 BTU x 224,000 BTU

However, you can always go one size smaller than my recommended one. It’s just that your garage will cool slower than “my standard”. If you use an 18,000 BTU mini split to cool an uninsulated 2-car garage with about 360 square feet, I estimate that your garage will cool from 95°F (35°C) to 75°F (24°C) in about 30 minutes.

In addition, don’t ever use an oversized mini split. Otherwise, the humidity level in your garage will not drop to around 55% relative humidity which is the standard comfortable air conditioning humidity level. If you can’t bring the humidity level down below 65%, mold may start to grow on everything.

Can You Install a Mini Split by Yourself?

Although many people install a mini split in their garage by themselves, it doesn’t mean that it’s easy. But, I assume you are a hands-on guy and you are ready to make it happen.

Almost all mini splits come with an installation kit including refrigerant pipes, drain hoses, cables and accessories. With a 3.5″ hole saw cutter, you are able to install a mini split in your garage within a day.

However, most mini splits don’t include an outdoor unit mounting bracket, so you’ll have to buy one. This DuctlessAire universal outdoor mounting bracket (click to view on Amazon) is a good one, suitable for a 9000 BTU mini all the way to a 36000 BTU mini split.

However, the Daikin 19 series mini split heat pump (click to view on Amazon) that I recommended to you included the outdoor mounting bracket. So, you have one less thing to worry about.

Nevertheless, you can always put the mini split outdoor unit on the floor but make sure to prop it up using a concrete plinth or some sort of a base that can support the weight of the outdoor unit (~70 lbs).

You also can use this floor standing bracket from Senville to jack up your mini split to prevent water from going into the unit and staying inside the unit.

Also, don’t forget to check if you have any nearby power outlets for the mini split. Most of the time, a single phase 230V power is required to be connected to the mini split condenser.

Then, using the communication cable that comes with the mini split that connects the indoor and outdoor unit, it is able to power the mini split air handler.

Nonetheless, I suggest you get a professional to install so that you don’t void the warranty. Most manufacturers don’t warranty anymore if their products are not installed by a professional HVAC technician. So, be careful.

How Far Can a Mini Split Be From the Condenser?

Most mini split air handlers can be placed nearly 100 ft from their condenser. However, most of them are pre-charged with a refrigerant enough for 25 ft only. Beyond that, you’ll need to charge in an extra amount of refrigerant which often requires a professional to do.

If you buy from Amazon, they typically come with 16 ft refrigerant pipes and cables only. So, you can expect to put the condenser about 10 ft away from the mini split air handler to allow some buffer length. If you buy from Home Depot, they usually allow you to select the length of the refrigerant pipes and cables.

Where is the Best Place to Put a Mini Split?

Most of the time, the best place to put a mini split in a garage is on the wall where the condenser is mounted behind. It’ll make your installation work faster and easier.

One thing to consider is to try not to let the mini split blow directly onto your body while you’re working in your garage cause it’s unhealthy. Anyway, you can always adjust its airflow direction by setting the air swing.

I’ve covered exactly how high and where to put a mini split (both the indoor unit and the outdoor unit) in my post Best Place to Put the Mini Split Air Handler and Condenser. I suggest you check it out especially for the outdoor unit location. I’ve included some diagrams as a quick guide for the positioning of the mini split.

Conclusion

A mini split is a great heating and cooling solution for a garage. The most important thing is to get the right mini split capacity for your garage. If you are unsure, get a professional to assess your garage and have them install the mini split for you.

Yu Chang Zhen

Yu was working in the air conditioning industry for the past 7 years, covering from design to installation and maintenance. Yu wish to share all the things he learned with the people around the world.

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