Mini Split Math explains DIY ductless mini-split heat pumps using the numbers that manufacturers, the U.S. Department of Energy, ENERGY STAR, the EPA and AHRI publish, with every figure linked to its source.
Safety first. Refrigerant and electrical work have legal and safety requirements. Per the EPA, connecting or disconnecting pre-charged refrigerant lines on a mini-split requires Section 608 technician certification. Follow your unit’s installation manual, the National Electrical Code and local code. This site is general information, not a substitute for a certified technician or licensed electrician.
What we cover
- Choosing a system: sizing, efficiency ratings and cold-climate performance. See Choosing a System.
- Comparisons: model-vs-model specs from manufacturer documents. See Comparisons.
- Installation: line sets, electrical specs and the EPA refrigerant rules. See Installation.
- Costs and rules: operating cost, tax credits and refrigerant transitions. See Costs & Rules.
Who it’s for
Homeowners weighing a DIY ductless mini-split for a room, an addition, a garage or a whole floor.
How we research
- Manufacturer documents first. Capacity, SEER2, EER2, HSPF2, line sizes, refrigerant charge and electrical ratings come from the maker’s spec sheet, support pages and installation manual. We link the exact page and note the date we checked it.
- Official sources. Sizing guidance comes from DOE’s Building America Solution Center; efficiency definitions from AHRI; cold-climate criteria and tax-credit information from ENERGY STAR; refrigerant rules from the EPA; energy conversions and electricity prices from the EIA.
- Codes and standards by reference. Load calculations point to ACCA Manual J and electrical guidance to the NEC. Your local code official always has the final word.
- Like for like. We compare efficiency on the same basis (HHV vs LHV) and say when a figure is a test-condition maximum.
- No first-hand claims. We don’t run equipment tests and don’t claim personal use of the products we describe.
- Editorial review. Before publishing, each article goes through an automated editorial check for unsupported claims, math and safety wording. Every factual correction is confirmed against the primary source before it’s made.
- Kept current. Models get discontinued and programs end. Pages carry a “last checked” date.
How affiliate links work
Some links may become affiliate links. If you buy through one, the site may earn a commission at no extra cost to you. Commissions never decide a recommendation. Details are on the affiliate disclosure page.
What this site isn’t
Mini Split Math isn’t an HVAC dealer, manufacturer, installer or code authority, and it isn’t affiliated with any brand it mentions. All trademarks belong to their owners.
Corrections
Found an outdated spec, a discontinued model or a mistake? Tell us through the contact page with the page URL and, ideally, the manufacturer’s document.