For cold-climate homes where a quick-connect install matters more than price: it holds its full heat far colder than other quick-connect units. Flare-connect units match its cold-weather output for much less.
Price checked October 21, 2026. As an Amazon Associate we earn from qualifying purchases.
The rating comes from 5 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 | 18,000 Btu/h |
| Heating at 17 °F (max) | 20,300 Btu/h |
| Heating at 5 °F (max) | 18,000 Btu/h |
| Heat kept at 5 °F | 100% |
| Price per 1,000 Btu/h at 5 °F | $176 |
| Efficiency (certified) | |
| HSPF2 (Region IV) | 11 |
| SEER2 | 21.2 |
| EER2 | 12.5 |
| COP at 5 °F | 1.99 |
| ENERGY STAR | ENERGY STAR Cold Climate |
| AHRI certificate | 216032551 |
| Operating range | |
| Heats down to | -22 °F |
| Cooling range | -22 to 122 °F |
| Installation | |
| Line set connection | Quick-connect (no vacuum pump) |
| Line set | 25 ft included, up to 75 ft |
| Voltage | 230 V |
| Refrigerant | R-454B |
| Indoor unit | DIY-18-HP-WMAH-230D25-O |
| Outdoor unit | DIYHH-18-HP-C-230D25-O |
| Build | |
| Indoor noise | 20.5–54.5 dB(A) |
| Outdoor noise | 58 dB(A) |
| Wi-Fi | Built in |
| Room size (maker) | up to 800 sq ft |
| Weight | indoor 35.5 lb / outdoor 99.9 lb |
| Warranty | 7 yr compressor, 5 yr parts |
| Warranty with DIY install | Yes |
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 $1,981.82The cheapest way into a certified, cold-capable heat pump, for a self-installer with a vacuum pump. Pioneer’s Quantum Ultra and the quick-connect Klimaire DIY have near-identical certified ratings.
Amazon $1,319.96 Della $1,499.96Compare the MrCool DIY Hyper Heat 5th Gen 18,000 BTU 230V with any other DIY mini-split →
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