How to Install a Mini Split (Step-by-Step)

How to install a mini-split, step by step — a clear two-track guide separating the DIY pre-charged path from the pro (traditional, EPA-608) path, with the tools and the electrical spelled out.

The first seven steps are the same whether you DIY or hire out — the difference is Step 6, the refrigerant. A pre-charged DIY system lets you finish it yourself; a traditional system hands Step 6 to an EPA-608 technician.

Step-by-step

  1. Size & site the unit. Pick the BTU capacity with the sizing calculator; choose an indoor wall (~7–8 ft high, 3 ft clear airflow) and a level, shaded outdoor spot with 12 in+ clearance, raised 4–6 in.
  2. Mount the wall bracket. Find the studs, level the mounting plate and screw it to the indoor wall.
  3. Drill the pass-through hole. A ~3 in hole, angled slightly downward, for the line set, control wiring and condensate drain.
  4. Hang the indoor head on the plate; feed the line set, wiring and drain through the hole.
  5. Set & connect the outdoor condenser on its pad or bracket; route and connect the line set to the service valves.
  6. The refrigerant — the fork:
    • DIY (pre-charged / no-vac): tighten the sealed quick-connect couplers to spec. No vacuum, no gauges, no EPA license.
    • Traditional: flare the fittings, pull a deep vacuum, then open the valves / charge and leak-check — this legally requires EPA Section 608 certification.
  7. Electrical. Run a dedicated 208/230V circuit on its own breaker (110–120V for some small units). Have a licensed electrician do this.
  8. Commission & start up. Open the service valves, power on, run a pressure/leak check (~30–60 min), test heating and cooling, and confirm the condensate drains.
  9. Permit & inspection. Pull the permit before work; many areas inspect the electrical and refrigerant work.

Tools you’ll need

Frequently asked questions

Can you legally install a mini split yourself?

You can legally DIY a pre-charged, quick-connect system, because the refrigerant lines stay sealed. For a traditional system, opening the refrigerant circuit — flaring, vacuuming and charging — legally requires EPA Section 608 certification, so that part must be done by a certified technician.

Do you have to vacuum a mini split before charging?

For a traditional system, yes — you must pull a deep vacuum to remove air and moisture from the lines before releasing refrigerant, using a vacuum pump and manifold gauges. Pre-charged “no-vac” DIY kits skip this step because the line set comes factory-sealed and you just tighten the quick-connect couplers.

Do you need an EPA license to install a mini split?

For a traditional system, yes — connecting and charging the refrigerant lines requires EPA Section 608 certification. Pre-charged DIY systems are exempt because the refrigerant stays sealed and you never open the circuit. The electrical work should still go to a licensed electrician either way.

What tools do you need to install a mini split?

A pre-charged DIY kit needs only basic hand tools plus a drill and hole saw, a level and wrenches. A traditional install also requires a vacuum pump, manifold gauges, and torque and flaring tools — the equipment (and certification) that makes it a pro job.

Safety first: refrigerant handling on a traditional system is legally restricted to EPA-608-certified technicians, and the electrical circuit must be wired by a licensed electrician. This guide is an overview, not a substitute for the manufacturer’s manual or a permit.