A Comprehensive Guide: Installing a Mini Split Ductless AC Unit With a Heat Pump

Introduction

Greetings, YouTube! It’s Boxing Day 2020, and I hope you all had a fantastic holiday season. Today, we’re diving into a highly practical and somewhat essential project for anyone involved in woodworking or craftwork: installing a mini split ductless air conditioning unit with a heat pump in your workshop. You might be wondering, "What does this have to do with woodworking?" Well, quite a lot, actually. Maintaining a constant temperature in your workshop isn’t just a matter of comfort and safety—it’s essential for the wood that you store and work with. Temperature fluctuations can cause wood to expand and contract, leading to warping, which is something we obviously want to avoid at all costs.

So, why now? A few weeks ago, I walked into my workshop, ready to build a cross-cut sled for my table saw. The space was freezing—30 degrees to be exact. I tried to fire up my old wall-mounted AC unit with a heat pump, but the motor had burned out. Now, this wasn’t just a window unit; it’s a larger wall unit with a heat pump that cost over $800. Further complicating things, it was too loud to use while recording. The perfect solution? A mini split ductless system, known for being whisper-quiet, which allows for recording while maintaining a constant temperature. Today, we’ll go through the step-by-step process of installing this unit.

What is a Mini Split Ductless AC Unit?

Before we jump into the installation process, let’s clarify what a mini split ductless AC unit is. Essentially, it’s an air conditioning system that does not require ductwork. It consists of two primary components:

1. Outdoor Condensing Unit: This is the external part of the system, responsible for extracting heat from the inside and expelling it outside.
2. Indoor Unit: This unit is mounted inside the room, delivering cool or warm air to the space.

These units are connected by a set of electrical wires and two small refrigerant tubes, making the installation simpler compared to traditional HVAC systems. Mini splits are highly efficient and often quieter than other types of AC units, making them a fantastic option for workshops.

Unboxing and Preparation

Let’s start by unboxing the components: a 9000 BTU mini split system designed for a 12 by 20 workshop.

Components:

1. Outdoor Condenser Unit
2. Indoor Unit
3. Decorative Cover Kit (to hide the copper tubing)
4. Ground Rack (for the condenser unit)
5. Copper Tubing Kit

All in all, this setup cost around $800, cheaper than replacing my old wall unit. Once unboxed, we need to gather the necessary tools and materials, including a stud finder, drill, silicone sealant, electrical conduit, wire, and a vacuum pump for refrigerant evacuation.

Step 1: Connecting the Power Source

Tap into Existing Outlet:

1. Safety First: Turn off the power to the existing 240-volt outlet that supplied power to the old AC unit.
2. Drill a Hole: Drill through the outlet box, siding, and into the outside wall.
3. Insert Wiring: Run a 12-gauge wire through a flexible conduit and feed it through the drilled hole.
4. Seal the Hole: Apply silicone sealant around the hole to prevent any unwanted elements from seeping in and to maintain temperature integrity.
5. Connect the Wires: Affix the conduit to the outside wall and connect the wires to a cutout switch for safety.

Word of Caution: I’m not a licensed electrician. I have some experience from my time in the Navy, but I highly recommend hiring a professional to handle any electrical work.

Step 2: Preparing and Positioning the Indoor Unit

Locate Studs for Mounting:

1. Use a Stud Finder: Locate two studs in the wall where you plan to mount the indoor unit.
2. Mounting Bracket: Secure the mounting bracket to the wall, ensuring it is level. Use the studs for extra support. The bracket came with screws and anchors, but I prefer using studs for more secure anchoring.

Drill a Hole for Tubing and Wiring:

1. Mark the Spot: Measure and mark a spot four inches horizontally and two inches up from the bracket for a 2.5-inch hole.
2. Drill at an Angle: The hole should be drilled at a slight downward angle to ensure condensation can drain out properly.

Step 3: Preparing the Interior Unit

Connect the Wires:

1. Access the Control Panel: Open the access cover on the back of the interior unit.
2. Feed the Control Wire: Feed the control wire through the back and connect it to the corresponding terminals (1, 2, 3, and ground).

Preparing the Copper Tubing:

1. Gentle Bends: Carefully bend the copper supply lines to avoid kinking.
2. Attach to Wall: With the copper tubing, drain pipe, and control wire protruding, push them through the drilled hole.

Step 4: Positioning and Connecting the Outdoor Unit

Setup the Ground Rack:

1. Assembly: Assemble the ground rack and place the condenser unit on top of it, securing it firmly.

Connect the Power:

1. Wire Connections: Connect the 240-volt power to the condenser unit, attaching the hot wires to L1 and L2 and grounding appropriately.

Connecting the Control Wire:

1. Match Colors: Ensure that the colors of the wires match between the indoor and outdoor units (e.g., red to terminal 1, black to terminal 2, white to terminal 3, and green to ground).

Step 5: Connecting the Copper Tubing

Run Copper Tubing:

1. Length and Bend: Measure and cut the copper tubing as needed. Carefully bend it to avoid breaking or kinking.
2. Nylog Application: Apply Nylog sealant on the flared ends and threads before connecting.
3. Tighten Connections: Hand-tighten the connections and then use a wrench for final tightening, but do not over-tighten to avoid damaging the tubing.

Step 6: Evacuating the System

Setup the Vacuum Pump:

1. Connect: Attach a vacuum pump to the access port of the condenser and the blue low-pressure valve.
2. Run the Pump: Let it run for 15 minutes to evacuate the system, ensuring the blue side needle reads negative 30 or better.

Leak Check:

1. Turn Off: Close the blue low-pressure valve and turn off the vacuum pump.
2. Monitor: Wait for 15 minutes. If the needle didn’t move, there were no leaks.

Step 7: Final Steps

Release Refrigerant:

1. Quarter Turn: Turn the top valve one quarter turn for five seconds to release the refrigerant into the system.
2. Check Pressure: Ensure that the system shows proper pressure and checks for any leaks.
3. Disconnect the Vacuum Hose: Carefully remove the hose from the access port while wearing protective gloves.

Open Valves:

1. Fully Open: Open both the top and bottom valves entirely to allow normal refrigerant flow.

Moment of Truth

Power On:

1. Switch On: Turn the system on. If it beeps, that’s a good sign.
2. Temperature Display: The temperature should be displayed, and you should start feeling cool air.

I’m thrilled to say that the mini split system is now operational, and it’s incredibly quiet, perfect for maintaining a stable temperature in my workshop without disrupting recordings.

Conclusion

Installing a mini split ductless AC unit with a heat pump in your workshop is a valuable DIY project. It not only provides comfort and safety but also ensures the wood and materials you work with remain stable and free from warping due to temperature changes. While we’ve covered the general steps to install such a system, it’s crucial to remember that electrical work can be dangerous and may require a licensed professional. My experience in the Navy gave me some foundational knowledge, but for those unfamiliar with electrical components, hiring an expert is the best course of action.

Ultimately, the investment in a mini split system is well worth it. It offers greater efficiency, quiet operation, and precise climate control, making your workshop an ideal environment for woodworking or any craft. Plus, you’re saving on labor costs by doing it yourself, though always with caution and respect for the technical aspects involved.

If you found this guide helpful, consider subscribing to the channel and hitting the like button. This project was a success, and I’m looking forward to more woodworking and DIY endeavors in the comfort of my perfectly climate-controlled workshop. Until next time, take care and happy woodworking!