ACiQ Extreme Heat 18,000 BTU
#3 in 18,000 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.
The ACiQ Extreme Heat 18,000 BTU is the better mini-split overall, rated 4.7 to 2.1. The ACiQ Extreme Heat 18,000 BTU leads on warranty and efficiency.
MrCool DIY Select 18,000 BTU 230V
#22 in 18,000 BTUFull review
For mild climates and occasional use, where a low price for a quick-connect unit matters most. The short warranty and weak cold-weather output make it a poor main heat source.
Amazon $1,690 MRCOOL DIY Direct $1,690$1,690
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.
Which should you buy?
- Choose the ACiQ Extreme Heat 18,000 BTU for warranty (12-year compressor, 7-year parts vs 2-year compressor, 1-year parts) and efficiency (11 HSPF2, 21.4 SEER2, COP 1.92 at 5 °F vs 8.5 HSPF2, 17.3 SEER2, COP 1.75 at 5 °F).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every 18,000 BTU mini-split; a clear win is highlighted. How we rank explains each one.
| Factor weight | ACiQ Extreme Heat 18,000 BTU | MrCool DIY Select 18,000 BTU 230V |
|---|---|---|
| Overall rating | 4.7/5 | 2.1/5 |
| Cold weather 40% | 100 keeps 100% of its heat at 5 °F, heats down to -22 °F | 6 keeps 53% of its heat at 5 °F |
| Efficiency 30% | 72 11 HSPF2, 21.4 SEER2, COP 1.92 at 5 °F | 11 8.5 HSPF2, 17.3 SEER2, COP 1.75 at 5 °F |
| Warranty 20% | 100 12-year compressor, 7-year parts | 0 2-year compressor, 1-year parts |
| Noise 10% | 98 indoor unit from 19.5 dB(A) | 100 indoor unit from 18.5 dB(A) |
Specifications
| ACiQ Extreme Heat 18,000 BTU | MrCool DIY Select 18,000 BTU 230V | |
|---|---|---|
| Capacity (certified) | ||
| Size (nominal) | 18,000 BTU | 18,000 BTU |
| Cooling at 95 °F | 18,000 Btu/h | 17,000 Btu/h |
| Heating at 47 °F | 18,000 Btu/h | 18,000 Btu/h |
| Heating at 17 °F (max) | 19,200 Btu/h | 18,700 Btu/h |
| Heating at 5 °F (max) | 18,000 Btu/h | 9,500 Btu/h |
| Heat kept at 5 °F | 100% | 53% |
| Price per 1,000 Btu/h at 5 °F | - | $178 |
| Efficiency (certified) | ||
| HSPF2 (Region IV) | 11 | 8.5 |
| SEER2 | 21.4 | 17.3 |
| EER2 | 12.5 | 9 |
| COP at 5 °F | 1.92 | 1.75 |
| ENERGY STAR | ENERGY STAR Cold Climate | Not ENERGY STAR |
| AHRI certificate | 216032336 | 218004486 |
| Operating range | ||
| Heats down to | -22 °F | - |
| Cooling range | -22 to 122 °F | - |
| Installation | ||
| Installed by | Professional (sold through installers) | Sold for self-install (DIY) |
| Line set connection | Flare fittings (vacuum pump needed) | Quick-connect (no vacuum pump) |
| Line set | up to 98.4 ft | 11.5 ft included, up to 75 ft |
| Voltage | 230 V | 230 V |
| Refrigerant | R-454B | R-454B |
| Indoor unit | ACIQ-18W-HH-MD | DIYS-18-HP-WMAH-230A13-O |
| Outdoor unit | ACIQ-18ZPL-HP230C | DIYS-18-HP-C-230A11-O |
| Build | ||
| Indoor noise | 19.5–49.5 dB(A) | 18.5–46.5 dB(A) |
| Outdoor noise | 59 dB(A) | 55 dB(A) |
| Wi-Fi | Optional module | Built in |
| Room size (maker) | - | up to 800 sq ft |
| Weight | indoor 27.3 lb / outdoor 99.9 lb | indoor 30.6 lb / outdoor 62.6 lb |
| Warranty | 12 yr compressor, 7 yr parts | 2 yr compressor, 1 yr parts |
| Warranty with DIY install | No, a licensed installer is required | Yes |