Why it matters
The COSTWAY 9,000 BTU 230V Mini-Split, 21 SEER2 is rated at 9,000 BTU of cooling and 10,000 BTU of heating. On the ENERGY STAR room sizing chart that suits about 350 to 400 sq ft of average room; the maker says up to 450 sq ft. It needs a 230V (208/240V) circuit, which usually means an electrician if one isn't already at the spot.
Its 21 SEER2 ranks 5 of 10 among the mini-splits within about 12% of its capacity that we cover; the most efficient is the DELLA Optima 9,000 BTU 230V at 23. The listing doesn't give a low-temperature heating limit, so treat it as a mild-climate heat pump until the maker confirms one. Indoor noise is listed at 28 dB at its quietest setting.
Like most split systems it ships pre-charged for a set line length; connecting it means flaring, pulling a vacuum and opening the valves, a licensed technician's job in most places. It uses R-32 refrigerant, one of the lower-impact A2L refrigerants new systems moved to in 2025.
The listing gives dimensions of 7.48 inD x 31.93 inW x 12.05 inH, a shipping or unit weight of 19.8 pounds and a 710 W power draw.
Who it's for, and who should skip it
Good fit if
- Rooms of about 350-400 sq ft
- Large rooms and garages
Look elsewhere if
- Primary heat in cold climates
- Spaces much larger than 400 sq ft
- Owners who want to avoid a licensed install
Pros and cons
Pros
- 21 SEER2
- 10,000 BTU heating stated
- Quiet indoor head (28 dB)
Cons
- Low-temperature heating not stated
- Needs a 230V circuit
- Professional install recommended
Limitations to weigh
- Capacity and efficiency are the maker's ratings; real output depends on the install, the line length and the weather.
- Heat pumps lose heating capacity as it gets colder; size for your climate with the BTU calculator.
- The federal 25C tax credit ended for systems installed after 2025; check your utility for current rebates.
Specifications
Every figure below comes from the source shown in brackets. Where the maker doesn't state something, we say so instead of estimating.
| Capacity | 0.75 tons | Retailer |
|---|---|---|
| Cooling capacity (maker) | 9000 BTU | Retailer |
| Features (seller) | 4 Way Swing, Fast Cooling, Heating & Cooling Function, Inverter Compressor, Sleep Mode | Retailer |
| Dimensions (seller) | 7.48"D x 31.93"W x 12.05"H | Retailer |
| SEER (maker) | 21 | Retailer |
| Voltage | 230 V AC | Retailer |
| Noise (seller) | 28 db | Retailer |
| Refrigerant | R-32 | Retailer |
| Wattage | 710 W | Retailer |
| Room size (maker) | 450 sq ft | Retailer |
| Heating capacity (maker) | 10000 BTU | Retailer |
| Model number | Blast Pro | Retailer |
| Product weight | 19.8 lb | Retailer |
| Control | App, Remote, Voice | Retailer |
| SEER2 (maker) | 21 | Retailer |
Alternatives worth comparing
More ductless mini-splits we cover
- Garvee 12,000 BTU 230V Mini-Split
- Rellytech 18,000 BTU 230V Mini-Split, 19 SEER2
- Rellytech 17,000 BTU 230V Mini-Split
- DELLA Serena 9,000 BTU 230V
All ductless mini-splits, compared in one table · Every COSTWAY product we cover
Final verdict
A solid choice for a 350-400 sq ft room. Check that 9,000 BTU fits your room with the BTU calculator before you buy.
Where to buy
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