ACiQ Extreme Heat 24,000 BTU
#2 in 24,000 BTUFull review
ACiQ’s cold-climate line, sold online, keeps most of its rated heat at 5 °F, heats to −22 °F and gets a 12-year compressor warranty once registered. A certified technician has to install it.
4.6/5
Mitsubishi’s flagship cold-climate system: it makes more than its rated heat at 5 °F and keeps heating to −22 °F. For a home that relies on it as the main heat through a cold winter.
- 24,000 BTUSize
- 26,600 Btu/hHeat at 5 °F
- 134%Kept at 5 °F
- 10.5 / 23.5HSPF2 / SEER2
- Pro installInstall
See it at Mitsubishi
No store we check sells it online; the maker lists where to buy or who installs it.
Pros
- Makes 26,600 Btu/h at 5 °F, more than its rated 19,800 Btu/h
- Keeps heating down to −22 °F
- 10-year parts and compressor warranty once registered
Cons
- Needs a licensed HVAC installer: a self-install voids the warranty
How it scores
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.
Specifications
| Capacity (certified) | |
|---|---|
| Size (nominal) | 24,000 BTU |
| Cooling at 95 °F | 20,800 Btu/h |
| Heating at 47 °F | 19,800 Btu/h |
| Heating at 17 °F (max) | 29,200 Btu/h |
| Heating at 5 °F (max) | 26,600 Btu/h |
| Heat kept at 5 °F | 134% |
| Efficiency (certified) | |
| HSPF2 (Region IV) | 10.5 |
| SEER2 | 23.5 |
| EER2 | 13.3 |
| COP at 5 °F | 2.04 |
| ENERGY STAR | ENERGY STAR Cold Climate |
| AHRI certificate | 215912359 |
| Operating range | |
| Heats down to | -22 °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-FX24NL |
| Outdoor unit | MUZ-FX24NLHZ |
| Build | |
| Indoor noise | 27–53 dB(A) |
| Outdoor noise | 55 dB(A) |
| Wi-Fi | Built in |
| Weight | indoor 31.6 lb / outdoor 124 lb |
| Warranty | 10 yr compressor, 10 yr parts |
| Warranty with DIY install | No, a licensed installer is required |
| Released | 2025-02 |
Alternatives in this size
Fujitsu Orion XLTH 24,000 BTU
#3 in 24,000 BTUFull review
Fujitsu’s cold-climate line, with more than its rated heat at 5 °F and very high certified efficiency, for homes heating through a cold winter.
Senville Aura 24,000 BTU
#4 in 24,000 BTUFull review
A cold-climate unit sold online by Senville that keeps most of its rated heat at 5 °F and heats to −22 °F. Parts cover is 5 years, half the compressor’s 10.
Senville $1,799.99$1,799.99
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