DIY Mini Split Installation

Introduction: DIY Mini Split Installation

About: Hi Everyone, I'm Jeremy Hoffpauir. I write instructables about unique DIY woodworking and home improvement projects. I use unique design elements with a rustic coastal style in my creations such as epoxy...

Hey Everyone, I'm Jeremy Hoffpauir. I live in South Louisiana where the climate is very hot and humid for more than half of the year. I spend a lot of time in my workshop, so I decided to install a DIY mini split AC and heat pump for temperature and humidity control. The Mr Cool DIY 18,000 BTU 1.5 Ton Ductless Mini-Split Air Conditioner and Heat Pump (model: DIY-18-HP-230A) fit my needs, so I purchased the unit.

Workshop and Home Office

My workshop is a separate building from my main house and it has 2 levels. The first level is my workshop and the second level is my home office. I decided it was best to remove the original HVAC system. It was very old and not worth the cost of repair.

Home Office

I decided to install a ductless mini split in my home office during the fall of 2016. After many hours of research, I installed the Mr Cool DIY 18,000 BTU 1.5 Ton Ductless Mini-Split Air Conditioner and Heat Pump (model: DIY-18-HP-230A) for my home office. I did not worry about cooling or heating my downstairs workshop because winter was near. Additionally, I decided to test the performance of the ductless mini split in my home office before deciding on a cooling and heating system for my workshop. Workshop I was pleasantly surprised with the performance of the DIY mini split in my home office and decided to purchase the same unit for my workshop. I learned how to install a mini split during the first installation, so I decided to make a video and document my second mini split installation.

Why this Mini Split

I chose the Mr Cool DIY mini split (model DIY-18-HP-230A) because of DIY installation, price, features, and size.


Mr Cool DIY mini splits are DIY units as the name implies. The refrigerant lines are pre-charged with R410A refrigerant, which eliminates the need for a professional installation. The Mr Cool mini split install process is straightforward for an intermediate to advanced DIY’er – check out my video. I learned how to install a mini split with relative easy by following the instructions provided with the unit.


The total price for the Mr Cool DIY Mini Split was $1,457.00 plus $50.00 for the wall mount bracket. The total price was $1507.00 before tax.

I received multiple quotes from HVAC professionals on installing a similar unit to the Mr Cool DIY-18-HP-230A and the prices ranged from 2.5 to 3 times more than the Mr Cool DIY mini split. There are certainly many reasons and advantages to hiring an HVAC professional to install a mini split or conventional system. This was my workshop and home office; therefore, I decided it was worth the risk to buy the DIY mini split unit and install it myself. If I were faced with the same decision for my home, I probably would have chosen to hire an HVAC professional. Reputable HVAC professionals guarantee their installation, support manufacturer warranties, and provide service agreements.

Mini Splits versus traditional central HVAC systems are beyond the scope of this article. If you are faced with this decision, I encourage you research these topics and decide what is best for your situation and environment.

Mr Cool DIY Features

The features of the Mr Cool DIY mini split supported my needs even though it may not have the features of more expensive brands. Below are the features I like most:

Dual heat pump and AC unit.

Refrigerant leakage detection system ensures the system operates efficiently without degradation due to corrosion.

WiFi adapter allows it to be connected to the Internet and controlled remotely via an app.Warranty:

7 year compressor and 5 year parts.Low Noise:

57dBA decimal rating.

Variable Speeds

Louver Position Memory and Swinging capability.

Mr Cool DIY Mini Split Size

There are different Mr Cool DIY mini split size models for different size areas. The Mr Cool DIY mini split model I purchased and installed covers 850 square feet. I was concerned with the 18′ high ceilings in my workshop, so I purchased this unit which covers more square feet than my workshop. My workshop is approximately 600 square feet.

How to Install a Mini Split Overview

I'll the main steps I performed to install the Mr Cool DIY mini split. These steps provide a good overview of the process. This process is not meant to replace the manufacturers instructions; rather, it is a supplemental aid. Be sure to check out my video for more additional detail.

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Tools and Unboxing

Tools I used in this project:

Mr Cool DIY 18k BTU 16 SEER Ductless Mini-Split Heat Pump w/ WiFi

Outdoor Mounting Bracket

Milwaukee 3.5" Hole Saw

Magnetic I-beam level, 48"

Digital IR Thermometer Dual Laser

Stanley Metric and SAE Hex Keys

Drill/Driver Combo

Heavy Duty Wrench


I ordered the Mr Cool DIY mini split online and it arrived in 2 boxes: the outside condenser unit and the inside unit. Both boxes were packaged very well. I inspected each part for damage very carefully. The refrigerant hose is connected to the inside unit and wrapped with a plastic coating and tie wraps.

Step 2: Assemble Wall Bracket

I purchased the wall mount for the outside condenser unit separate. I chose the wall mount option rather than mounting the unit on a slab. It is easier to assemble the wall mount bracket before installation rather than in the middle of the installation.

Step 3: Mount Inside Unit

I used the metal bracket and cardboard template to mount the inside unit.

Before proceeding, I attached the drain hose and checked for any links by running water through it.

I chose to mount the inside unit at the back wall of my workshop below the staircase. Under normal circumstances, the inside unit is mounted directly to a wall, but the back wall in my shop is not ideal for air flow. The back wall provided convenient access to the back of my workshop and the electrical junction box. I constructed a wooden support frame that matched the cardboard wall template and securely mounted it to the underside of the staircase.

Next, I slowly bent the refrigerant lines to match the location where I planned to drill the exit hole – straight back. The refrigerant lines can exit the unit to the right, left, or directly back (default is left).

Next, I examined the plastic latches. The plastic latches were not broken or damaged.

I lifted the unit and set it on the metal bracket.

Step 4: Drill Hole & Route Refrigerant Bundle

I drilled the 3.5″ hole with a hole saw bit and 3/8″ arbor at a downward angle for proper drainage.

Next, I installed the round plastic sleeve into the hole.

I fed the refrigerant piping through the hole. I removed the protective passive wrap after the piping was through the wall.

Next, I mounted 2 garage bike hooks to the bottom of the staircase so the pipe bundle could rest in them and keep them straight. I put the drain hose through the hole below the refrigerant pipe bundle.

There was a trim piece to the plastic pipe, but I didn’t use it. I plan to build a box to hide the refrigerant pipe at a later date, so I decided to use spray foam to seal the hole.

Step 5: Mount Outside Unit

The outside wall bracket for the condenser unit was easy to mount. I made sure the cross support piece was level and secured it to the wall with screws. Next, I slid the 2 support arms on the cross support piece.

Next, I slid the 2 support arms on the cross support piece.

I heard a buzzing sound around my thigh while mounting the bracket. I noticed a wasp nest about 6 inches away from my leg. Thankfully, I didn’t get stung by one of them!

The outside condenser unit weighs 80 pounds. It’s not very heavy, but it is definitely awkward. I placed the unit on the support arms and made sure the rubber feet and bolts were aligned correctly. Next, I tightened them with a wrench and socket.

I used my magnetic I-beam level to make sure the top of the unit was perfectly level.

Step 6: Connect Refrigerant Lines & Electrical

Next, I wrapped the excess refrigerant piping around the outside of the bracket in wide, loose loops. I removed the top plastic cap to expose the electrical components and the bottom water tray to expose the refrigerant piping.

After removing the plastic seals on top of the high and low side, I immediately attached the refrigerant piping.

I aligned the refrigerant pipes and made sure they were not stressed. After I tightened each screw connector by hand, I tightened the bottom screw connector and then the top according to the instructions.

The instructions are very specific, so I made sure to read them carefully. The couplings work with tapping rings, so they may leak if the pipes are loosened and reconnected. I removed the cover on the top valve and opened the valve with a 19mm hex wrench counterclockwise. I repeated this process on the bottom valve.

Next, I checked for leaks with a spray bottle that contained dawn soap and water.

Next, I connected the electrical cable from the inside unit to the outside unit. I made the electrical connections, attached the water box and electrical box, and put pipe installation around the refrigerant pipes.

I’m not including the electrical part of the installation process because I’m simply not qualified to provide this advice to you. I encourage you to call a professional electrician to perform this work because it is not worth the risk.

Step 7: Install Remote Mount, Filters, & WiFi Adapter

Next, I installed the remote control cradle and the batteries. I installed the remote control cradle near the door to my workshop.

I climbed up my ladder and installed the air filters.

The USB WiFi adapter was easy to install as well. The port is located on the underside of the door.

Step 8: Setup WiFi and App

Once I connected to the SSID of the unit, I opened up the Mr. Cool app and configured the unit. The app doesn’t have the same features as the remote control, but it is still very useful. I have 2 units and I chose the workshop unit.

I can change modes from cool, to dry, to heat, to auto and back to cool by pressing the mode button.

I turned the unit off by hitting the power button to the lower left of your screen.

I can set a schedule for the unit to turn on and off at a certain time. This works well, but I still login after it is supposed to shutoff because I’ve noticed that sometimes it doesn’t shut off.

Step 9: Test Unit

There are specific instructions in the installation manual for testing the unit. I used my IR thermometer to measure the cold air exiting the unit. This unit cooled my 25’x25’ workshop with 18’ ceilings quickly. I’m very happy with it.

Tools I used in this project:


I hope this project provided you with some value because this is, and always will be, my ultimate goal. If you would like to see more of my projects, subscribe to my YouTube channel and visit my website.

Until next time – Imagine…Create…Share

Step 10: UPDATE (8-18-2017): Mini Split Stopped Working!

I had to file a warranty claim on one of my DIY mini splits in my workshop. Check out my blog post and the video here for more detail.

Be the First to Share


    • Magnets Challenge

      Magnets Challenge
    • Snow Challenge

      Snow Challenge
    • Wearables Contest

      Wearables Contest

    4 Discussions


    2 years ago

    so awesome! I live in AZ and it is very hot here in the summer. Given my shop is in the garage, I am definitely going to do this. Thanks for sharing!


    Reply 2 years ago

    You are very welcome. It's hot in South Louisiana, but not as hot as it is in Arizona. However, we do have 95% humidity here so it feels very hot.

    Let me know if you have any questions - I'm happy to help!


    2 years ago

    The installation looks good. We're thinking of installing a larger unit in our greenhouse because the small one just isn't cutting it.


    Reply 2 years ago

    Thank you very much! I am very pleased with this unit. It is my second one and it does a great job cooling and heating my workshop and home office.
    Let me know if you have any questions when you install yours - I'm happy to help you if I can.