DIY Olis Mini-Split Install: Heat, Cool & Save Thousands

Installing a mini-split heat pump can seem daunting, but it's a DIY project that can save you thousands. I recently walked through the full process for an Olis 115V unit, and the most surprising takeaway was just how straightforward the critical steps, like flaring and vacuuming, can be with the right approach.

Disclosure: Olis sent this unit for testing. All opinions and test results are my own.

What I Built

I installed an Olis 115V mini-split heat pump. This unit included the main condensing unit, an indoor head, 3/8-inch and 1/4-inch insulated copper line sets, communication and power cables, a drain hose, remote, mounting hardware, and a cardboard mounting template. My installation required mounting the indoor unit above a door in a space-constrained area. The provided mounting template needed a slight adjustment (about half an inch) on the right side to align perfectly with the unit's actual dimensions, which I corrected with a pencil line. I also rerouted the drain line from the right to the left side of the indoor unit, which involved removing a black plug and twisting a silver clip to release and reposition the drain. I drilled an angled hole through the wall to ensure proper drainage for the lines and used a separate line hide kit to keep the exterior lines clean and protected from sunlight, as the included line set was only about 10 feet long.

For the wiring, I connected black to line, white to neutral, and ground to the ground screw, following the 115V specifications. The red wire was taped off as it wasn't needed for this configuration. It’s important to match the numbered communication wires (1, 2, 3) between the indoor and outdoor units, so taking a picture of the connections before disassembly is always a good idea.

Why It Works

The core of a successful mini-split installation lies in creating a sealed, dry refrigerant system. Flaring the copper pipes correctly is crucial for leak-free connections. I used a flaring tool with a built-in clutch, which prevents over-tightening and ensures a perfect flare every time. For the connections, I applied Nylog Blue to the mating surfaces of the flare nuts, not the threads, to maintain proper torque values and enhance the seal.

Vacuuming the system is perhaps the most critical step. This process removes all non-condensable gases, primarily water vapor, from the refrigerant lines. A vacuum pump lowers water's boiling point to ambient air temperature, causing it to vaporize and be drawn out. To significantly speed up this process, I used a valve core removal tool to take out the Schrader cores from the service ports, creating a much larger opening for the vacuum pump. After reaching a deep vacuum (below 500 microns), I closed off the connections and monitored the micron gauge for any rise, confirming a leak-free system. Reinserting the Schrader cores was done under slight positive pressure to prevent any air from being sucked back into the evacuated lines.

Parts & Specs

• Heat Pump: Olis 115V Mini-Split (12,000 BTU cooling, 12,500 BTU heating)
• Refrigerant: R32 (0.6kg pre-charged)
• Line Sets: 3/8-inch and 1/4-inch copper (insulated, ~10 ft included)
• Power: 115V, Min. Circuit Amps 19.4A, Max Fuse 30.0A
• Tools Used (examples from video): Tubing cutters, deburring tool, flaring tool with clutch, digital torque wrench (15-25 N·m for 1/4", 35-40 N·m for 3/8"), vacuum pump (Fieldpiece VP67), micron gauge (NAVAC NMV1), Appion valve core removal tools, Big Blu Microleak Detector.
• Additional Purchases: Longer line set (if needed), exterior line hide kit.

Math & Run-Time Numbers

The Olis unit comes pre-charged for 3-5 meters (approx. 10-16 feet) of refrigerant piping. For my 22-foot (6.7 meter) line set, I calculated the need to add approximately 1 ounce of R32 refrigerant, based on the manual's guidance of 16 grams per meter for a 12,000 BTU unit.

During the vacuum process, my micron gauge quickly dropped to 135 microns, well below the 500-micron target, indicating a dry system. A subsequent hold test showed only a slight rise in micron levels, which I attributed to a minor leak in my external gauge fitting, not the installed system.

When testing in cooling mode, the unit achieved an impressive temperature split: return air was around 67°F, while the supply air was a chilly 35°F. That's a 32°F split, confirming excellent cooling performance. In heating mode, the return air was around 79°F, and the supply air reached a toasty 144°F, demonstrating a strong heating output.

Pros & Cons

Pros:

• DIY-friendly with the right tools and guidance.
• Significant cost savings compared to professional installation.
• Effective cooling (32°F temperature split observed).
• Powerful heating (144°F supply air observed).
• Flexible drain line routing.
• Comes with essential installation accessories.

Cons:

• Mounting template might require minor adjustments.
• Included line set may be too short for some installations, requiring separate purchase.
• Specific HVAC tools (vacuum pump, torque wrench, flaring tool) are essential and may need to be acquired.
• Initial unit arrived with minor cosmetic shipping damage.

When To Use This vs. Alternatives

This Olis mini-split is a fantastic option for homeowners and tinkerers looking to add efficient heating and cooling to a garage, workshop, or a single room without the high cost of a professional HVAC installation. If you're comfortable with basic DIY tasks, willing to invest in a few specialized tools (or rent them), and want energy independence, this is a solid choice. However, if you need a whole-home solution, prefer not to handle refrigerant, or are uncomfortable with the technical aspects, a professional HVAC system might be a better fit. Its 115V operation also makes it ideal for running off portable power stations and solar setups, offering an easy path to energy independence.

Bottom Line

The Olis 115V mini-split heat pump proved to be an excellent DIY project. While it requires attention to detail and a few specialized tools, the installation process is manageable, and the unit delivers impressive heating and cooling performance. For anyone looking to take control of their climate control and save money, this is a highly recommended option.

Final Wrap-Up

If you found this guide helpful, be sure to subscribe to the "There's A Trick For That" YouTube channel for more DIY solar and home energy projects. You can also find links to all the tools and products I used in the video description, and feel free to ask questions in the comments below!