Mitsubishi’s standard line, quiet and efficient, for milder winters: it loses a good share of its heat in deep cold and stops heating at −5 °F.
No store we check sells it online; the maker lists where to buy or who installs it.
The rating comes from 4 measured or published factors, each scored 0-100 against fixed reference points for its size. How we rank explains each one.
| Capacity (certified) | |
|---|---|
| Size (nominal) | 12,000 BTU |
| Cooling at 95 °F | 12,000 Btu/h |
| Heating at 47 °F | 14,400 Btu/h |
| Heating at 17 °F (max) | 12,000 Btu/h |
| Heating at 5 °F (max) | 10,100 Btu/h |
| Heat kept at 5 °F | 70% |
| Efficiency (certified) | |
| HSPF2 (Region IV) | 10.7 |
| SEER2 | 25.6 |
| EER2 | 13.3 |
| COP at 5 °F | 1.80 |
| ENERGY STAR | ENERGY STAR Cold Climate |
| AHRI certificate | 216626285 |
| Operating range | |
| Heats down to | -5 °F |
| Cooling range | 14 to 115 °F |
| Installation | |
| Installed by | Professional (sold through installers) |
| Line set connection | Flare fittings (vacuum pump needed) |
| Line set | up to 65 ft |
| Voltage | 230 V |
| Refrigerant | R-454B |
| Indoor unit | MSZ-GX12NL |
| Outdoor unit | MUZ-GX12NL |
| Build | |
| Indoor noise | 19–45 dB(A) |
| Outdoor noise | 49 dB(A) |
| Wi-Fi | Built in |
| Weight | indoor 23 lb / outdoor 77 lb |
| Warranty | 10 yr compressor, 10 yr parts |
| Warranty with DIY install | No, a licensed installer is required |
| Released | 2025-03 |
Full rated heat in deep cold at a fair price, for a self-installer comfortable with a vacuum pump. Della’s Optima Pro has near-identical certified ratings for a little less.
Amazon $1,398 Pioneer Mini Split store $1,398Very efficient and quiet, for mild winters: it stops heating below 5 °F, so a cold climate needs Fujitsu’s Orion XLTH instead.
For mild to moderate winters: it heats only down to −4 °F and loses some of its heat in deep cold.
Compare the Mitsubishi GX 12,000 BTU with any other mini-split →
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