Quick answer
A single-zone mini-split installed back to back, with the outdoor unit directly behind the indoor head, takes about four to six hours, one working day at most. A multi-zone system takes one to two days: allow roughly two to four extra hours for each additional head, and more when line sets run through an attic or a finished basement ceiling.
A mini-split installation takes four to six hours for a single-zone system and one to two days for a multi-zone one. The equipment goes up quickly; the time is in the connections and in the tests that prove them. What stretches a job is the wall, the drain, the electrical run and the number of heads.
Single-zone back-to-back versus multi-zone with long line sets
The quickest install is back to back: the indoor head on an outside wall and the outdoor unit directly behind it, joined by a line set a couple of metres long through one hole. With the panel nearby, two installers finish that in four to six hours. Put the outdoor unit around the corner or a storey down, and the line set, drain and cable travel in a cover along the wall, which adds an hour or two.
On a multi-zone system each added head brings its own line set, drain, control cable and wall penetration back to the one outdoor unit. Allow roughly two to four hours per extra head, toward the top of that range when lines pass through an attic, a finished basement ceiling or a branch box. Two or three heads usually fit in one long day or a day and a half, and four or five make a two-day job. The layouts are compared in single-zone versus multi-zone mini-splits.
A typical single-zone installation day, step by step
- Walk-through and layout: confirm the head height, the line route and the outdoor spot before anything is drilled.
- Mount the indoor bracket and core the wall, sloped slightly to the outside for the drain.
- Set the outdoor unit on its pad or wall bracket and level it.
- Run and connect the line set, drain and control cable, then flare and torque the joints.
- Pressure test with nitrogen, then evacuate the lines.
- Electrical: the circuit from the panel, the disconnect at the outdoor unit and the final connections.
- Release the charge, start up, test cooling and heating, and go through the remote and the filters with you.
The steps that cannot be rushed
Four steps take the time they take, and a crew that halves them is borrowing against the compressor's life.
- Flare or braze. Each flare is cut square, deburred, formed with the right tool and tightened with a torque wrench to the manufacturer's figure. Larger multi-zone systems may have brazed joints, made with nitrogen flowing through the pipe.
- Nitrogen pressure test. The lines are pressurized with dry nitrogen and left standing while the gauge is watched. A slow leak needs time to show, so a two-minute test is no test.
- Vacuum to 500 microns. A vacuum pump and a micron gauge pull the lines down to 500 microns or lower, then the pump is valved off to see whether the reading holds. Long line sets and humid days make this slower.
- Electrical disconnect and circuit. The outdoor unit gets a dedicated circuit and a disconnect switch within sight of it, wired by a licensed electrical contractor with an ESA notification filed.
Site factors that add time to a mini-split install
- Brick or stone walls. Coring a three-inch hole through vinyl siding and wood framing takes minutes. Double-wythe brick on a pre-war house, or stone on a century farmhouse, takes a diamond core bit and far longer.
- No gravity drain. When the head sits on an interior wall or below grade, the condensate cannot fall to the outside, and a small condensate pump is added and wired.
- Wall bracket or pad. A ground pad on levelled gravel is quick. A wall bracket keeps a heat pump above the snow line but needs solid anchoring and vibration isolators.
- Electrical distance. A panel on the far side of a finished basement means fishing cable, and a full panel may need a sub-panel first.
- Line sets longer than the factory charge allows. Extra refrigerant is weighed in, which adds a step.
Century farmhouses in rural Flamborough and Caledon, with thick stone walls, sit at the slow end of the range. A vinyl-sided house in a 1990s subdivision, with the panel on the same wall as the outdoor unit, sits at the fast end.
Days on site and installed cost by number of heads
- One head, one outdoor unit: $4,000–$7,000 installed, usually a single day.
- Two heads: $7,500–$11,000 installed, one long day or a day and a half.
- Three to four heads: $10,000–$16,000+ installed, about two days.
Before the crew arrives, clear a metre of space below the head location and around the outdoor spot, and make sure the electrical panel can be reached. You can stay in the house throughout, and the power may be off briefly while the new breaker goes in. Central air on existing ducts follows a different schedule, described in how long an AC installation takes.
ZK Mechanical quotes ductless mini-split installation from a site visit, so the written quote states the number of days along with the price. We work across Burlington, Oakville, Milton, Hamilton, Mississauga, Brampton and the west side of Toronto. Call (647) 801-1252 or book the site visit. A finished example is the single-zone ductless project, and the cooling answers cover what comes after the install.