The Definitive Guide: What Size Hole for Mini Split Line Set?

When it comes to installing a mini-split system, the size of the hole for the line set is a critical detail that can make or break the success of your DIY project. As an expert on this topic, I’m here to provide you with a comprehensive, step-by-step guide on determining the optimal hole size and ensuring a seamless installation process.

Understanding the Mini-Split Line Set

The mini-split line set is the collection of components that connect the indoor and outdoor units of your mini-split system. This set typically includes the refrigerant lines, electrical wiring, and the condensate drain line. Ensuring that the hole size is appropriate for the line set is essential to prevent any leaks, obstructions, or structural compromises.

Determining the Ideal Hole Size

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The standard diameter for the hole required to accommodate the mini-split line set is 2 3/8″ (60.3 mm). This measurement has been carefully calculated to provide ample space for the various components of the line set, allowing for a smooth and efficient installation.

Factors to Consider

When determining the location of the hole, it’s crucial to take into account the positioning of the wall studs. Failing to account for the studs can lead to complications during the installation process. To ensure a successful outcome, consider the following factors:

  1. Stud Location: Use a stud finder or carefully inspect the wall to identify the location of the wall studs. This information will be crucial in determining the optimal placement of the hole.

  2. Manufacturer’s Template: Many mini-split manufacturers provide a cardboard template that can be used to mark the precise location of the hole. Utilize this template to ensure accurate measurements and placement.

  3. Measurements from the Indoor Unit: If a manufacturer’s template is not available, you can take measurements directly from the backside of the indoor unit. This will help you determine the optimal hole location to align with the line set connections.

  4. Horizontal Shifting: If a stud is in the way of the desired hole location, you may need to shift the metal wall plate for the indoor head unit horizontally to ensure the 2 3/8″ hole will miss the stud.

Drilling the Hole

Once you have determined the optimal location for the hole, it’s time to start the drilling process. For this task, you’ll need a 2 3/8″ hole-saw bit. This specialized tool will ensure a clean, precise cut through the wall, accommodating the line set with ease.

Protecting the Line Set

In some cases, you may choose to use a protective sleeve for the line set as it passes through the wall. If this is your preferred method, you’ll need to use a 2″ schedule 40 PVC sleeve. In this scenario, you’ll need to drill a 2 3/8″ hole to accommodate the sleeve.

Considerations for Multiple Zones

It’s important to note that each indoor unit in a multi-zone mini-split system will require its own line set, drain, and electrical connections to the outdoor unit. This means that you’ll need to drill one hole per zone to accommodate the respective line sets.

Running the Line Set Through Wood Studs

In situations where the line set needs to pass through wood studs, you can consider an alternative approach. This involves cutting out a horizontal piece of drywall, drilling 1/2″ (12.7 mm) holes in the studs, and then running the line set to the exterior. However, it’s crucial to maintain the structural integrity of the studs during this process.


By following the guidelines outlined in this comprehensive guide, you can ensure that the hole you drill for your mini-split line set is the perfect size, allowing for a seamless and efficient installation. Remember to always prioritize safety, consult manufacturer instructions, and take the necessary precautions to protect the structural integrity of your walls. With the right tools and attention to detail, you can successfully complete your mini-split installation project.