Slim Concealed Duct Mini Split Install

Step-by-Step Tutorial: Installing a Slim Concealed Duct Mini Split System

1. Prepare the Attic Space

   • Lay down rough flooring in the attic for easier and safer working conditions.
   • Attach two by fours across the ceiling joists and lay sheets of OSB on top for stability.

2. Measure and Cut Struts

   • Measure the lengths of the struts needed to mount the air handler to the rafters (e.g., 49.5 inches).
   • Cut rods for the taller and shorter sections based on the measurements.

3. Mount the Air Handler

   • Mount the air handler in place, securing it to the rafters.

4. Install Custom Plenums and Duct Fittings

   • Find transitions and duct boots that fit your setup or consider getting custom plenums and duct fittings made.
   • Drill pilot holes from the attic down into the rooms to mark where to cut ceiling holes for the ducts.

5. Attach Duct Boots

   • Apply mastic on the seams of each boot to seal any gaps.
   • Attach each boot to flex duct using zip ties and tape, then insulate the boot.

6. Place Boots in Sealing Holes

   • Carry the duct boots into the attic and place them in the ceiling holes.
   • Seal any gaps between the boots and the drywall with mastic and secure them in place.

7. Secure Ducts and Attach Registers

   • Strap the ducts to the rafters in the attic, mapping out their path to the supply plenum.
   • Attach registers to the ducts and secure the supply plenum to the air handler.

8. Connect the Return Side

   • Attach a plenum, air filter cabinet, and transition from the air filter to the duct for the return side.
   • Secure the 16-inch return duct to the handler, making sure it fits snugly.

9. Set Up Condensation Pump and Line Set

   • Set up PVC piping to run condensation out of the unit and across the attic.
   • Install the line set by running it through the sidewall of the house and bending the pipes using a tube bender.

10. Connect Line Set to Unit and Condenser

    • Cut the line set to size and flare the ends before attaching them to the unit and condenser.
    • Use a torque wrench fitting to secure the attachments precisely.

11. Connect Thermostat and Power Supply

    • Connect the thermostat to the unit and the main power supply through a disconnect switch.

12. Install the Condenser

    • Mount the condenser to the concrete in the backyard.
    • Connect the other end of the line set to the condenser.

13. Vacuum and Pressure Test the Lines

    • Conduct multiple rounds of vacuuming and nitrogen pumping to remove air and moisture from the lines.
    • Use a micron gauge to monitor the pressure level during vacuuming.

14. Release Refrigerant and Test

    • Once the lines are clear of air and moisture, release the refrigerant by opening the valves.
    • Turn on the system and check for cold air output to ensure proper functionality.

Following these steps will help you successfully install a slim concealed duct mini-split system in your home.