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) | 18,000 BTU |
| Cooling at 95 °F | 18,000 Btu/h |
| Heating at 47 °F | 21,600 Btu/h |
| Heating at 17 °F (max) | 18,200 Btu/h |
| Heating at 5 °F (max) | 15,200 Btu/h |
| Heat kept at 5 °F | 70% |
| Efficiency (certified) | |
| HSPF2 (Region IV) | 10.3 |
| SEER2 | 22.5 |
| EER2 | 14.1 |
| COP at 5 °F | 1.80 |
| ENERGY STAR | ENERGY STAR Cold Climate |
| AHRI certificate | 215862736 |
| 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 100 ft |
| Voltage | 230 V |
| Refrigerant | R-454B |
| Indoor unit | MSZ-GX18NL |
| Outdoor unit | MUZ-GX18NL |
| Build | |
| Indoor noise | 28–49 dB(A) |
| Outdoor noise | 54 dB(A) |
| Wi-Fi | Built in |
| Weight | indoor 37 lb / outdoor 116 lb |
| Warranty | 10 yr compressor, 10 yr parts |
| Warranty with DIY install | No, a licensed installer is required |
| Released | 2025-02 |
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 $1,878 Pioneer Mini Split store $1,878A quick-connect unit with one of the longest warranties for a self-install, priced below MrCool’s DIY 5th Gen. Its −4 °F heating limit rules it out as the only heat in a very cold climate.
Amazon $1,981.82For mild to moderate winters: it heats only down to −4 °F and loses some of its heat in deep cold.
Compare the Mitsubishi GX 18,000 BTU with any other mini-split →
More from Mitsubishi: every Mitsubishi product ranked.
