Mitsubishi Hyper-Heat GX 12,000 BTU
#9 in 12,000 BTUFull review
Mitsubishi’s mainstream Hyper-Heat line keeps its full rated heat at 5 °F and heats down to −13 °F. The FX goes further in deep cold and efficiency.
The Mitsubishi Hyper-Heat GX 12,000 BTU rates 4.4 among 12,000 BTU mini-splits; the Mitsubishi GX 18,000 BTU rates 3.6 among 18,000 BTU ones.
Mitsubishi GX 18,000 BTU
#14 in 18,000 BTUFull review
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.
Prices were last checked October 21, 2026 and are subject to change; the price and availability shown by the retailer at the time of purchase apply.
Scores side by side
These two sit in different size classes (12,000 BTU and 18,000 BTU), and each is scored against the reference points for its own class, so a rating says how well each does among its own size peers. How we rank explains each factor.
| Factor weight | Mitsubishi Hyper-Heat GX 12,000 BTU | Mitsubishi GX 18,000 BTU |
|---|---|---|
| Overall rating | 4.4/5 | 3.6/5 |
| Cold weather 40% | 87 keeps 100% of its heat at 5 °F, heats down to -13 °F | 39 keeps 70% of its heat at 5 °F, heats down to -5 °F |
| Efficiency 30% | 62 10 HSPF2, 25.6 SEER2, COP 1.80 at 5 °F | 59 10.3 HSPF2, 22.5 SEER2, COP 1.80 at 5 °F |
| Warranty 20% | 100 10-year compressor, 10-year parts | 100 10-year compressor, 10-year parts |
| Noise 10% | 100 indoor unit from 19 dB(A) | 57 indoor unit from 28 dB(A) |
Specifications
| Mitsubishi Hyper-Heat GX 12,000 BTU | Mitsubishi GX 18,000 BTU | |
|---|---|---|
| Capacity (certified) | ||
| Size (nominal) | 12,000 BTU | 18,000 BTU |
| Cooling at 95 °F | 12,000 Btu/h | 18,000 Btu/h |
| Heating at 47 °F | 12,300 Btu/h | 21,600 Btu/h |
| Heating at 17 °F (max) | 16,000 Btu/h | 18,200 Btu/h |
| Heating at 5 °F (max) | 12,300 Btu/h | 15,200 Btu/h |
| Heat kept at 5 °F | 100% | 70% |
| Efficiency (certified) | ||
| HSPF2 (Region IV) | 10 | 10.3 |
| SEER2 | 25.6 | 22.5 |
| EER2 | 13.3 | 14.1 |
| COP at 5 °F | 1.80 | 1.80 |
| ENERGY STAR | ENERGY STAR Cold Climate | ENERGY STAR Cold Climate |
| AHRI certificate | 216626288 | 215862736 |
| Operating range | ||
| Heats down to | -13 °F | -5 °F |
| Cooling range | 14 to 115 °F | 14 to 115 °F |
| Installation | ||
| Installed by | Professional (sold through installers) | Professional (sold through installers) |
| Line set connection | Flare fittings (vacuum pump needed) | Flare fittings (vacuum pump needed) |
| Line set | up to 65 ft | up to 100 ft |
| Voltage | 230 V | 230 V |
| Refrigerant | R-454B | R-454B |
| Indoor unit | MSZ-GX12NL | MSZ-GX18NL |
| Outdoor unit | MUZ-GX12NLHZ | MUZ-GX18NL |
| Build | ||
| Indoor noise | 19–45 dB(A) | 28–49 dB(A) |
| Outdoor noise | 49 dB(A) | 54 dB(A) |
| Wi-Fi | Built in | Built in |
| Weight | indoor 23 lb / outdoor 82 lb | indoor 37 lb / outdoor 116 lb |
| Warranty | 10 yr compressor, 10 yr parts | 10 yr compressor, 10 yr parts |
| Warranty with DIY install | No, a licensed installer is required | No, a licensed installer is required |
| Released | 2025-03 | 2025-02 |