DIY Mini-Split Install: Save $9,000 on HVAC

I recently tackled a DIY mini-split installation that saved me nearly $10,000 compared to professional quotes. Using a $400 unit from Amazon, I was able to bring efficient cooling and heating to my garage, proving that energy independence doesn't have to break the bank.

What I Built

I installed a Wifi 12000 BTU 115V / 19 SEER2 mini-split, a perfect size for my garage. The kit came with everything needed, including a template for mounting the indoor unit. Following the template, I drilled a 2.5-inch angled hole through the wall to route the refrigerant lines and drain tubing. I then wired the indoor unit's terminal block, carefully matching the labeled wires to the corresponding numbers. Once the lines were bundled with electrical tape, they were fed through the wall.

The outdoor unit connection involved cutting and flaring the copper refrigerant lines. I used Nylog Blue sealant on the flare connections to ensure a tight, leak-free seal. Before releasing the refrigerant, a proper vacuum evacuation was critical to remove any moisture from the lines. After the vacuum test, I released the refrigerant charge into the system. Finally, I installed the line cover outside to protect the lines from UV rays and provide a clean finish.

It's important to note that mini-split installation involves dangerous high voltage electricity and high-pressure refrigerant. This video is for informational/entertainment purposes only. I highly recommend you consult or hire qualified HVAC and electrical professionals.

Why It Works

This mini-split unit comes with several premium features that enhance its performance and durability. It includes a drain pan heater, which is crucial for cold weather operation, preventing ice buildup and allowing the unit to run efficiently even in low temperatures. The gold fin coils are another excellent feature, offering superior resistance to corrosion compared to standard coils, which extends the unit's lifespan.

The unit uses R454B A2L refrigerant, a modern, efficient option. A critical step in installation is pulling a deep vacuum to remove all non-condensable gases and moisture from the lines. This ensures optimal system performance and prevents long-term damage. Precise torque is also vital for flare connections to prevent leaks and maintain system integrity.

One standout feature is the "Gen Mode" (Generator Mode) in the app, which allows you to limit the mini-split's capacity to 30%, 50%, or 80%. This is fantastic for running the unit off a generator or portable power station without overloading it. Additionally, the unit boasts motorized horizontal and vertical vanes, offering precise control over airflow direction, a feature often found only on much more expensive models.

Parts & Specs

• Mini Split Model: Wifi 12000 BTU 115V / 19 SEER2 (Outdoor Unit A12115W20E12)
• Rated Voltage: 115V~, 60Hz, 1 Phase
• Refrigerant: R454B / 860g (30.34oz) A2L
• Compressor: 12.3A
• Minimum Circuit Amps (MCA): 17A
• Maximum Overcurrent Protection (MOP): 25A
• Included Components: Indoor head unit, outdoor unit, mounting template, wall mount bracket, mounting hardware, wall sleeve, trim ring, remote control, remote mount, batteries, outdoor unit drain port, power and communication cable, drain tubing, non-stick nylon tape, hole filling material, vibration isolation pads, additional insulation, 5 meters (3/8") line set, 5 meters (1/4") line set.
• Pro-Grade Tools Used: Navac flaring tool (NTF66 NTF66C), Fieldpiece vacuum pump (VP67), Navac micron gauge (NMV1), digital torque wrench. (Budget-friendly alternatives for many tools are available for rent or purchase).

Math & Run-Time Numbers

My real-world tests showed impressive performance from this unit. On a hot day, with return air at 79.6°F, the mini-split delivered supply air at a frigid 44.0°F, resulting in a fantastic 35.6°F temperature split. For heating, with return air at 83.0°F, the unit provided supply air at 115.0°F, giving a robust 32.0°F temperature split. These numbers highlight the unit's efficiency in both cooling and heating, especially considering the ambient temperatures.

Proper torque is crucial for flare connections. The manual specifies 15-20 Newton-meters (N.m) for 1/4" lines and 31-35 N.m for 3/8" lines. I always opt for the lower end of the range, applying 31 N.m to my 3/8" lines, to allow for future tightening if a minor leak were to occur, without risking overtightening.

Pros & Cons

• Pros:
  • Extremely affordable for a complete system.
  • Relatively easy DIY installation with included instructions and template.
  • Quiet operation for both indoor and outdoor units.
  • Excellent cooling and heating performance with high temperature splits.
  • Premium features like a drain pan heater, gold fin coils, and motorized horizontal/vertical vanes.
  • "Gen Mode" feature allows capacity limiting (30%, 50%, 80%) for generator or power station use.
  • Comprehensive app control with scheduling, eco mode, and self-diagnosis.
• Cons:
  • The indoor unit's filter fit is loose, potentially allowing dust to bypass the filter over time.
  • As a lesser-known brand, sourcing replacement parts might be challenging in the long run.

When To Use This vs. Alternatives

This mini-split is a fantastic option for homeowners and tinkerers looking to save significant money on installation costs without sacrificing performance. It's perfectly suited for conditioning spaces like garages, workshops, or adding supplementary heating and cooling to specific zones in your home. The unique "Gen Mode" makes it an ideal choice for off-grid applications or as a backup climate control solution when paired with a generator or large portable power station.

However, if you're uncomfortable with electrical wiring, working with high-pressure refrigerants, or drilling large holes in your home, professional installation is always recommended. While this unit offers incredible value, higher-end brands might provide better long-term parts availability or warranty support, but at a significantly higher upfront investment.

Bottom Line

For the price, the Really Tech mini-split is an incredible value. Its impressive performance, quiet operation, and DIY-friendly design, coupled with advanced features like "Gen Mode" and full app control, make it a top contender for anyone looking to save thousands on HVAC. Despite minor quirks, it delivers premium comfort without the premium price tag.

Final Wrap-Up

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