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Mr COOL DIY Mini Split Review: Exceptional SEER Ratings (2021)


There is nothing like the new Mr COOL DIY mini split series. While the big companies stopped innovating a decade ago, Mr COOL is literally a breath of fresh air of innovation in the HVAC industry. We will review Mr COOL mini-split systems; the trendsetter air conditioning/heat pump system.

Here is the quick outtake of the 3rd generation 12k, 18k, and 24k Mr COOL mini splits:

  • They have a high 20+ SEER rating and 10 HSPF rating (incredibly energy-efficient).
  • They are modernized; modern design, mobile app integration, great appeal.
  • Most importantly, you can DIY the installation.

Here’s the deal:

Installation of a mini-split unit averages at about $3,000.

If you can avoid that cost, you obviously would. Before Mr COOL, only the incredibly technical people managed to DIY a mini-split (barely). With the Mr COOL mini-splits, you get an incredibly efficient, easy to install device.

Here are two conditions to avoid that $3,000 installation cost:

  1. Be just a bit of a technical person (we’re not talking rocket science; basic DIY skills will do).
  2. Buy the Mr COOL DIY unit of appropriate capacity (you have to choose between 12k, 18k, 24k, 36k models – more on that later on).

Mr COOL DIY 3rd generation mini-split units don’t need professional installation. In this Mr COOL mini split review, we will look at 12k, 18k, 24k, and 36k systems.

Here is an interesting part:

All Mr COOL mini splits are the future of air conditioning/heating. However, many people are shocked to find out that some Mr COOL models are better than others.

What really mind boggles some people is why is the smaller 12k unit more expensive than the bigger 18k and even 24k unit. We’ll explain in detail why the 12,000 BTU Mr COOL is such a smart investment.

Let’s first look at the comparison of the Mr COOL DIY mini-split. After that, we’ll explain which device is the best for a certain area and look into the energy-efficiency (the most important factor when buying any mini-split heat pump). We will also review each Mr COOL mini-split system (below the comparison table).

Comparison of Mr COOL DIY Mini Split System

Mr COOL Comparison: BTU (Capacity): Efficiency Specs, Rating, Price:


12,000 BTU Cooling

12,000 BTU Heating

Recommended Area: 500 sq. ft.

SEER rating: 22.0
HSPF rating: 10.0
(Voltage = 115 V)4.9 out of 5 stars


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18,000 BTU Cooling

18,000 BTU Heating

Recommended Area: 750 sq. ft.

SEER rating: 20.0
HSPF rating: 10.0
(Voltage = 230 V)4.7 out of 5 stars


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23,000 BTU Cooling

25,000 BTU Heating

Recommended Area: 1,000 sq. ft.

SEER rating: 20.0
HSPF rating: 10.0
(Voltage = 230 V)4.7 out of 5 stars


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34,500 BTU Cooling

36,000 BTU Heating

Recommended Area: 1,500 sq. ft.

SEER rating: 16.0
HSPF rating: 8.9
(Voltage = 230 V)3.9 out of 5 stars


Check Price

Which Mr COOL Mini Split To Choose (Based On Square Footage, Energy Efficiency)

As you can see, Mr COOL makes mini-split with different cooling/heating capacity (measured in BTU; British Thermal Units).

It’s important not to pick a mini-split that’s too big or too small for your needs.

Appropriately sizing a mini-split will lead you to either lower energy-efficiency (can cost $100s/year in electricity costs) or limit the lifespan of the device. Therefore you need to take into account the recommended areas for each Mr COOL DIY mini-split.

Here’s how big a mini-split you need:

  • For 500 sq. ft., choose the 12,000 BTU Mr COOL.
  • For 750 sq. ft., choose the 18,000 BTU Mr COOL.
  • For 1,000 sq. ft., choose the 24,000 BTU Mr COOL.
  • For 1,500 sq. ft., choose the 36,000 BTU Mr COOL.

If you’re somewhere between these recommended areas, you can give us your situation in the comments below or use our BTU calculator here.

Now, let’s look at the most important aspect of every mini-split system:

Energy-Efficiency (SEER And HSPF Rating)

Surprise: When you compare the prices of 12k. vs 18k. vs 24k Mr COOL DIY systems, you might notice that the smallest one (12k) has the same (or even higher) price tag as bigger 18k and 24k units. Energy-efficiency is the key here:

The whole point of buying an efficient Mr COOL mini-split is to reduce future electricity costs. Here we need to look at the specifications:

  • SEER rating (cooling). Industry-standard is 14-16 SEER rating (Mr COOL have 20 SEER rating).
  • HSPF rating (heating). Industry-standard is 8-9 HSPF rating (Mr COOL have 10 HSPF rating).

Based on these ratings, we can determine that Mr COOL mini-split units are any good; in fact, they are exceptional.

Some units are better than others. Here is how we can rank the Mr COOL mini-split systems:

  • 1st Place: 12,000 BTU unit with 22 SEER and 10 HSPF rating.
  • 2nd Place: 18,000 BTU and 24,000 BTU units with 20 SEER and 10 HSPF rating.
  • 3rd Place: 36,000 BTU unit with 16 SEER and 8.9 HSPF rating.

As you can see, the 12k Mr COOL DIY can command a higher price just because of its 22 SEER rating. That means that the 12k unit is about 10% energy-efficient than 18k and 24k. How does that translate into electricity dollars?

Simple: If the seasonal electricity bill for Mr COOL air conditioning is $1,000 for 18k and 24k unit, it will be only $900 for the 12k unit. Essentially:

Extremely efficient 12k Mr COOL can save you $100/year in electricity cost compared to 18k and 24k unit. In 10 years, that’s $1,000.

This is the very reason why the 12k unit can have the same or even higher unit cost compared to 18k and 24k device.

On the other hand, if you look at the SEER and HSPF rating of the 36k unit, you can see that the energy-efficient is not as splendid as the smaller Mr COOL mini-split units. You can find a better 36k unit; however, you won’t find a better 12k, 18k, or 24k unit.

That’s why we’ll review each of the best Mr COOL air conditioners – the 12k, 18k, and 24k.

Mr COOL DIY 12k Review

SEER Rating (Cooling): 22
HSPF Rating (Heating): 10
Cooling Capacity: 12,000 BTU
Heating Capacity: 12,000 BTU
Voltage: 115V
Rating: 4.9 out of 5 stars

The 12k unit by Mr COOL DIY is just remarkable in many aspects. Apart from superb energy-efficiency, it’s a highly modernized mini-split system; the likes you won’t yet see from even the biggest brands such as Mitsubishi or Fujitsu.

One key feature is the new SmartHVAC app. Standard mini-splits are controlled via a remote controller. The Mr COOL 12k can be controlled via iPhone or any Android phone. You don’t even have to leave the couch; increase or decrease the temperature with the scroll.

Of course, we can’t overestimate how essential the energy-efficiency is. In fact, the 12k model is the best mini-split in 2020 purely due to the 22 SEER rating. Its cooling effectiveness is 10% higher than most other mini-split units, including the Mr COOL 18k and 24k units. Add the HSPF heating rating, and you have an eco-friendly mini-split that will last for 15+ years.

The vital ingredient for such high efficiency is the variable-speed DC inverter compressor. This alone can cut the yearly cooling/heating costs by several $100.

The DIY process is easy: you get a pre-charged R-410A 25 quick connect line. You will be able to install the Mr COOL 12k without any specialized tools professional installers use.

On top of that, the 12k is the only Mr COOL DIY unit that runs on 115V. That means you don’t need any electrical work; you have low voltage and low amperage.

All in all, the 12k is the modern trendsetting air conditioner/heat pump. This is the future of all mini-splits.



  • Unbeatable 22 SEER rating with 10 HSPF rating
  • Only Mr COOL DIY unit that runs on 115V (even easier installation)
  • DIY installation saves you about $3,000
  • Affordable price given the low electricity costs you can expect in the next decade or two

  • Only for 500-600 sq. ft. spaces or smaller

Mr COOL DIY 18k Review

SEER Rating (Cooling): 20
HSPF Rating (Heating): 10
Cooling Capacity: 18,000 BTU
Heating Capacity: 18,000 BTU
Voltage: 230V
Rating: 4.7 out of 5 stars

18k units are very popular. You’ll rarely find 20 SEER, 10 HSPF rating mini split; that’s exactly what the Mr COOL 18k offers.

It has a DC-inverter compressor that is quiet and enables such high energy-efficiency.

What is more, it can cool down or heat places that are about 750 sq. ft. big. That means that it will fit well in big living rooms and bedrooms.

You also have all the modernization; not does the 18k have an inverter compressor, you can also use the SmartHVAC app to control it, and it has a modern design. That’s much more appealing than the classic mini-split heat pumps.



  • High 20 SEER and 10 HSPF
  • Can cooling/heat spaces around 750 sq. ft. big (1 big room, or 2 small ones)
  • Low price given the 18,000 BTU of power

  • Needs 230V voltage
  • Combined weight is 222 lbs, you’ll need strong arms for DIY installation

Mr COOL DIY 24k Review

SEER Rating (Cooling): 20
HSPF Rating (Heating): 10
Cooling Capacity: 23,000 BTU
Heating Capacity: 25,000 BTU
Voltage: 230V
Rating: 4.7 out of 5 stars

24k unit is the biggest Mr COOL unit that has a 20 SEER rating. You will also notice a bit of discrepancy as far as the cooling and heating capacity is concerned; the cooling capacity is 23,000 BTU and the heating capacity is 25,000 BTU.

This is the most popular big 1 zone mini-split unit. That means that you can use it to cool/heat the entire flat or several rooms. The total recommended area of use is 1,000 sq ft.

It’s quite an achievement that the 20 SEER (and 10 HSPF) can be achieved; higher capacity mini-splits usually have much lower energy efficiency.

All in all, if you need a bigger Mr COOL mini-split, this is the right choice. Needless to say, you will be able to DIY the installation and save yourself $3,000 installation cost.



  • Innovative big 24,000 BTU Mr COOL air conditioner
  • Managed to keep the high 20 SEER rating
  • Very quiet heat pump with low noise levels (like all Mr COOL units)
  • Can handle about 1,000 sq. ft. of space (entire flat, or several rooms)
  • Affordable price (below $2,000) for such a big device

  • Installation is a bit tougher due to a larger device
  • You will need 230V (but no amp breakers in most cases)

Verdict On Mr COOL

Undoubtely, the Mr COOL DIY mini-split units are the way of the future. The innovation is seen everywhere; from the design, DC inverter compressor, and WiFi connectivity to the SmartHVAC app.

In the future, we’re likely to see other companies following the Mr COOL footsteps. However, as of now, nobody has managed to snatch the holy grail of mini-splits:

To create a mini-split that everybody could DIY with ease.

With Mr COOL, you will not only save yourself the high installation costs, but due to high energy-efficiency, you will see your cooling/heating electricity bill reduced by several $100 per year.


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