The MRCOOL 5th Gen DIY 36K BTU Single Zone Mini-Split is the largest single-zone unit in the line, built for 1,300 to 1,600 square feet — a whole floor of a house, a large open-concept living space, or a workshop or barn you're heating and cooling as one zone.  

A traditional system this size almost always means a licensed HVAC contractor: running refrigerant lines, pulling a vacuum, and getting the system signed off before it's legally allowed to run. This system skips that process. The line set arrives pre-charged with refrigerant from the factory, so there's nothing to vacuum and no license required to connect it — which at this size can mean saving several thousand dollars in contractor labor, and not being stuck waiting on someone else's schedule for a job this big. It's the only ductless system on the market built this way, backed by a U.S. patent specifically for this pre-charged installation method (Patent No. 11,125,479).  

It runs on 230V power, the same as the 18K and 24K, so if you've already got a 230V circuit available (the kind that runs a dryer or electric range), you're most of the way to being ready. The pre-charged fittings are Intertek-tested and certified, meeting the same safety standards a contractor install would.  

Controls stay consistent across the line — remote, the MRCOOL app, or Alexa and Google Assistant — with the "Follow Me" sensor adjusting to wherever you're actually sitting. It's rated to keep heating down to about 5°F outside, and even at this size, the outdoor unit runs around 58 decibels — close to normal conversation. Efficiency comes in at 18 SEER2 — a step down from the smaller units in this line, since larger single-zone systems generally run less efficiently than smaller ones or multi-zone setups.  

Registering the unit gets you 5 years of parts coverage and 7 years on the compressor.