The Ultimate DIY Guide: How to Install a Concealed Duct Mini Split

Concealed duct mini splits offer a discreet and efficient cooling and heating solution for your home. This comprehensive guide will walk you through the advanced and critical steps to install a concealed duct mini split system, providing hands-on details and technical specifications for a successful DIY project.

Assess Your Space

Before starting the installation, it’s crucial to accurately measure the area where you plan to install the mini split. Consider the room’s dimensions, insulation, and heat load to ensure proper sizing. This will help you select the right unit that meets your cooling and heating needs.

Choose the Right Unit

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When selecting a concealed duct mini split system, look for models that offer a slim profile and short duct run, such as the Mitsubishi Ductless SEZ Unit. These units are designed to be easily concealed, making them an ideal choice for discreet installation.

Prepare the Installation Site

Ensure a safe and efficient work environment by laying down rough flooring in the attic or crawl space where you’ll be working. If necessary, install plywood to create a stable and level surface.

Mount the Handler

Securely mount the indoor unit handler to a wall or ceiling, ensuring proper clearance for airflow and maintenance access. Use sturdy brackets and lag screws to ensure a stable installation.

Mounting Considerations

  • Maintain a minimum clearance of 12 inches (30 cm) on all sides of the handler for proper airflow and access.
  • Use a stud finder to locate and secure the handler to the wall or ceiling studs.
  • Level the handler to ensure proper condensate drainage.

Install the Lineset

Connect the indoor and outdoor units with a lineset, which includes the suction, liquid, and control lines. Pressure test the lineset to ensure there are no leaks, and then purge the lineset of moisture before adding refrigerant.

Lineset Installation Steps

  1. Measure the distance between the indoor and outdoor units and select the appropriate lineset length.
  2. Use a flare tool to create flared connections on the ends of the lineset.
  3. Pressure test the lineset with nitrogen to a minimum of 500 PSI (34.5 bar) and check for any leaks.
  4. Evacuate the lineset using a vacuum pump to remove any moisture or non-condensable gases.

Seal the Ducts

Ensure airtight duct connections by using mastic or metal-backed tape to seal the duct joints. This will prevent air leaks and energy loss. Additionally, insulate the ducts to maintain temperature and efficiency.

Duct Sealing and Insulation

  • Apply a generous amount of mastic or metal-backed tape to all duct connections, overlapping the joints by at least 2 inches (5 cm).
  • Use duct insulation with a minimum R-value of R-6 to maintain temperature and prevent condensation.
  • Ensure the insulation is installed without gaps or compression, which can compromise its effectiveness.

Install the Linear Diffuser

Attach the linear diffuser to the duct, ensuring proper alignment and secure fastening. Connect the diffuser to the indoor unit, following the manufacturer’s instructions.

Diffuser Installation

  • Measure the duct opening and select a linear diffuser with the appropriate dimensions.
  • Use screws or rivets to securely attach the diffuser to the duct, ensuring a tight seal.
  • Connect the diffuser to the indoor unit using the provided ductwork connections.

Charge the System

Add the appropriate amount of refrigerant to the system, following the manufacturer’s guidelines. Use a vacuum pump to remove any air and moisture from the system before charging.

Refrigerant Charging

  • Refer to the manufacturer’s specifications for the correct refrigerant type and charge amount.
  • Use a digital refrigerant scale to accurately measure the refrigerant charge.
  • Evacuate the system to a deep micron level (500 microns or less) to ensure the removal of all moisture and non-condensable gases.

Test the System

After the installation is complete, thoroughly test the system to ensure proper operation. Check for any leaks, verify the airflow, and confirm the temperature control.

System Testing

  • Perform a leak test by pressurizing the system with nitrogen and checking for any pressure drops.
  • Measure the airflow at the linear diffuser to ensure it meets the manufacturer’s specifications.
  • Verify the temperature control by checking the system’s ability to maintain the desired set point.

Install Thermostat or Control System

Follow the manufacturer’s instructions to install the thermostat or control system. Ensure proper wiring and placement for optimal control and user convenience.

Thermostat/Control System Installation

  • Mount the thermostat or control panel in a location that is easily accessible and away from direct sunlight or drafts.
  • Connect the thermostat or control system to the indoor and outdoor units according to the manufacturer’s wiring diagrams.
  • Program the thermostat or control system to your desired settings and test its functionality.

By following these advanced and detailed steps, you can successfully install a concealed duct mini split system in your home, ensuring optimal performance and energy efficiency. Remember to always prioritize safety, use the appropriate tools and equipment, and refer to the manufacturer’s instructions for specific guidance.