DIY Mini Split Installation

I spend a lot of time in my workshop, so I decided to perform a DIY mini split installation for temperature and humidity control in my workshop.  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 perfectly.


Tools I Used for this DIY Mini Split Installation:



FREE DIY PLANS – Grab Your Free DIY Plans for this Project at the bottom of this post.


DIY Mini Split for 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 DIY mini split in my home office during the fall of 2016.  After many hours of research of DIY min split installation articles, 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.


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 DIY Mini Split

I chose the Mr Cool DIY ductless mini split (model DIY-18-HP-230A) because of the price, features, size, and it is 100% DIY.


MrCool 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 at the top of this post.  This DIY mini split installation was relatively straightforward and the instructions were well written.


The total price for the Mr Cool DIY Mini Split Installation was $1,457.00 plus $50.00 for the wall mount bracket.  The total price was $1457.00 before tax as of 2017.

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 Ductless Mini Split Overview

Below are 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 detail.


Step 1:  Unboxing

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.

How to Install a Ductless Mini Split - Unboxing

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.

How to Install a Ductless Mini Split - Wall Bracket Assembly


Step 3:  Mount Inside Unit

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

How to Install a Mini Split - Inside Unit Bracket and Template


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.

How to Install a Mini Split - Custom Wooden Mounting Bracket


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).

How to Install a Mini Split - Route Refrigerant Pipes


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

How to Install a Mini Split - Inside Unit Latches to Bracket


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

How to Install a Mini Split - Lift Inside Unit on Metal Frame


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.

How to Install a Mini Split - 3.5 inch hole


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

How to Install a Mini Split - Plastic Sleeve


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

How to Install a Mini Split - Route Refrigerant Pipes through hole


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.

How to Install a Mini Split - Drain hose through wall


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.