Ductless mini-split air-conditioners have risen in popularity dramatically in recent years. One study now pegs their domestic market share at more than 40 percent compared to larger-scale HVAC units—and the smaller systems are even more popular in Asia and Europe than in the US.

Mini-splits make a compelling climate control solution for a number of reasons. They are much smaller and easier to install than HVAC systems, they’re far less expensive, and they’re quiet. Many are sold at big-box stores and online, and enterprising DIYers can certainly install one without professional help, provided they have the required electrical connections. (Some mini-splits operate on 115 volts, but others require 220-volt wiring, which will likely mean a call to an electrician.) They’re also increasingly outfitted with smart features like mobile app support, tricks that you can’t do on HVAC units without a fancy thermostat.

Photograph: Chris Null

Bringing in the Pros

Della invited me to test its Optima 048-TP-12K1V-23S-IN mini-split, which offers 12,000 BTU of cooling and 12,400 BTU of heating capacity. Maximum power draw is 960 watts from a 115-volt circuit, and it’s rated to cover 550 square feet, or one small room. The manufacturer offered to cover the cost of professional installation, and I was eager for the pro install help. My home had a fairly recent-model mini-split installed when we bought the place, clearly picked up at Costco and set up by the owners themselves. The unit died within two years of our moving in, likely due to installation mistakes, according to the professionals who removed it.

ScreenshotDella+ app via Chris Null

Like most mini-splits, Della’s product arrived in three boxes, one for each primary component: The indoor air handler (the part you see on the wall inside), the compressor (the larger component that lives outside and circulates refrigerant), and the conduit that connects the two (including refrigerant lines, drain lines, and electrical wiring). Inside the home, the air handler is mounted to a metal bracket that’s also included. A template in the box directs installers where to attach the bracket to the wall and where to drill the conduit hole.

While the Della Optima costs only $921 (with coupon on Amazon), professional installation will run you considerably more than the hardware. A local provider here in Austin quoted $3,600 for the work.

On the day of installation, a crew of two spent about five hours removing the old mini-split and installing the new one, a process that was largely unremarkable except for the need to drill a new conduit hole, since the old unit’s hole was in a slightly different spot.