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 4.0. The ACiQ Extreme Heat 18,000 BTU leads on cold weather and warranty. The MrCool DIY 5th Gen 18,000 BTU 230V wins on efficiency.
MrCool DIY 5th Gen 18,000 BTU 230V
#11 in 18,000 BTUFull review
For someone who wants a true plug-together install with no tools beyond a drill, and a warranty that survives it. Expect to pay well over the price of a flare unit with the same cold-weather output.
Amazon MRCOOL DIY Direct $2,910$2,910
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 cold weather (keeps 100% of its heat at 5 °F, heats down to -22 °F vs keeps 71% of its heat at 5 °F, heats down to -13 °F) and warranty (12-year compressor, 7-year parts vs 7-year compressor, 5-year parts).
- Choose the MrCool DIY 5th Gen 18,000 BTU 230V for efficiency (11.5 HSPF2, 22.5 SEER2, COP 2.44 at 5 °F vs 11 HSPF2, 21.4 SEER2, COP 1.92 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 5th Gen 18,000 BTU 230V |
|---|---|---|
| Overall rating | 4.7/5 | 4.0/5 |
| Cold weather 40% | 100 keeps 100% of its heat at 5 °F, heats down to -22 °F | 52 keeps 71% of its heat at 5 °F, heats down to -13 °F |
| Efficiency 30% | 72 11 HSPF2, 21.4 SEER2, COP 1.92 at 5 °F | 92 11.5 HSPF2, 22.5 SEER2, COP 2.44 at 5 °F |
| Warranty 20% | 100 12-year compressor, 7-year parts | 64 7-year compressor, 5-year parts |
| Noise 10% | 98 indoor unit from 19.5 dB(A) | 100 indoor unit from 19 dB(A) |
Specifications
| ACiQ Extreme Heat 18,000 BTU | MrCool DIY 5th Gen 18,000 BTU 230V | |
|---|---|---|
| Capacity (certified) | ||
| Size (nominal) | 18,000 BTU | 18,000 BTU |
| Cooling at 95 °F | 18,000 Btu/h | 18,000 Btu/h |
| Heating at 47 °F | 18,000 Btu/h | 18,000 Btu/h |
| Heating at 17 °F (max) | 19,200 Btu/h | 20,300 Btu/h |
| Heating at 5 °F (max) | 18,000 Btu/h | 12,800 Btu/h |
| Heat kept at 5 °F | 100% | 71% |
| Price per 1,000 Btu/h at 5 °F | - | $227 |
| Efficiency (certified) | ||
| HSPF2 (Region IV) | 11 | 11.5 |
| SEER2 | 21.4 | 22.5 |
| EER2 | 12.5 | 13.7 |
| COP at 5 °F | 1.92 | 2.44 |
| ENERGY STAR | ENERGY STAR Cold Climate | ENERGY STAR Cold Climate |
| AHRI certificate | 216032336 | 216032545 |
| Operating range | ||
| Heats down to | -22 °F | -13 °F |
| Cooling range | -22 to 122 °F | -13 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 | 25 ft included, up to 75 ft |
| Voltage | 230 V | 230 V |
| Refrigerant | R-454B | R-454B |
| Indoor unit | ACIQ-18W-HH-MD | DIY-18-HP-WMAH-230D25-O |
| Outdoor unit | ACIQ-18ZPL-HP230C | DIY-18-HP-C-230D25-O |
| Build | ||
| Indoor noise | 19.5–49.5 dB(A) | 19–54.5 dB(A) |
| Outdoor noise | 59 dB(A) | 58.5 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 35.5 lb / outdoor 93.5 lb |
| Warranty | 12 yr compressor, 7 yr parts | 7 yr compressor, 5 yr parts |
| Warranty with DIY install | No, a licensed installer is required | Yes |