The DIY Mini Split Buying Checklist

Right-size it

• Run our BTU calculator — don't trust sqft rules of thumb on Amazon
• In climate zones 4 and colder, heating drives the size. Size on the heating load, not cooling
• Kitchens: add +4,000 BTU for cooking load
• Vaulted ceilings (12 ft+): multiply capacity by 1.4×
• Poor insulation (1920s drafty): +20% vs average; spray-foamed new build: –15%
• Never round up more than one standard size — oversizing short-cycles and kills the compressor

Cold-climate truth test

• Marketing says "works in cold weather." Ignore it
• Find the spec sheet. Look for rated capacity at 5°F (not just operating range)
• If the spec-sheet 5°F number is missing or italicized, the unit will underperform below freezing
• Truly cold-climate DIY (quick-connect): MrCool DIY Hyper Heat (−22°F), plus Zone Air (−13°F)
• Pro-install cold-climate picks: Mitsubishi H2i, Fujitsu XLTH, Daikin Aurora
• Your 99% design temp matters — find it at energystar.gov for your zip

Are you a good DIY candidate?

• You're buying a pre-charged DIY model — not a standard Mitsubishi / Daikin line
• You can run a 240V circuit, or will hire an electrician ($300–$600) for that one step
• You have a helper for the afternoon (outdoor condenser = two-person lift)
• The install is single-zone (or you're comfortable stepping up to multi-zone)
• You own a torque wrench — or will buy one. Flare nuts MUST be torqued to spec
• You're ok cutting a 3" hole through the exterior wall

Brand cheat sheet