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This 19 SEER2 vs 17 SEER2 mini split air conditioner guide compares two units with different efficiency ratings and capacities. Both models provide heating and cooling using inverter technology. The Rellytech offers higher SEER2 and larger coverage, while the COSTWAY focuses on quieter operation and more fan speeds. You need to decide which specs match your room size and comfort needs.
SEER Rating
19 SEER2
17 SEER2
Cooling Capacity
18,000 BTU
12,000 BTU
Heating Capacity
18,400 BTU
12,300 BTU
Coverage Area
1,250 Sq. Ft.
750 sq ft
Fan Speeds
4 speeds
5 speeds
Operating Modes
4 modes
7 modes
Choose the first if
- You need to cool or heat a larger space up to 1,250 square feet.
- You want the highest available energy efficiency rating for lower operating costs.
- You require higher heating capacity for colder winter conditions.
Choose the second if
- You are cooling a smaller room under 750 square feet.
- You prefer more granular control with five fan speed settings.
- You want additional operating modes like sleep and turbo for specific comfort needs.
Verdict
Choose the Rellytech if you need more power and efficiency for a larger area. Pick the COSTWAY if you are cooling a smaller room and want more flexible fan and mode settings. Both units use inverter technology for steady temperature control.
19 SEER2 vs 17 SEER2 Mini Split
Coverage Area
Edge: Rellytech 18000 BTU 230V Mini Split
The Rellytech unit covers up to 1,250 square feet, making it suitable for larger spaces like whole-home comfort, bedrooms, offices, or garages. In contrast, the COSTWAY model is rated for up to 750 square feet. This difference aligns with their respective capacities, as the Rellytech delivers 18,000 BTU for cooling while the COSTWAY provides 12,000 BTU. You should choose the Rellytech if you need to cool a larger room or open area. The COSTWAY is better suited for smaller rooms where the lower capacity is sufficient. The larger coverage area of the Rellytech gives it a clear advantage for bigger spaces.
Energy Efficiency
Edge: Rellytech 18000 BTU 230V Mini Split
Energy efficiency is determined by the SEER2 rating, which measures cooling output divided by energy consumed. The Rellytech holds a 19 SEER2 rating, while the COSTWAY has a 17 SEER2 rating. A higher SEER2 number indicates better efficiency, meaning the Rellytech uses less electricity to produce the same amount of cooling. Both units use inverter technology to adjust compressor speed, but the Rellytech’s higher rating suggests lower operating costs over time. If reducing energy consumption is a priority, the Rellytech is the more efficient choice. The COSTWAY still offers efficient performance, but it trails the Rellytech in this specific metric.
Operating Modes
Edge: COSTWAY 12000 BTU Mini Split 17 SEER2
The number of operating modes allows you to tailor the airflow and temperature to your needs. The Rellytech offers four modes: cooling, heating, fan, and dry, along with a Smart Eco function. The COSTWAY provides seven modes, including cool, heat, dry, fan, auto, sleep, and ECO. The additional modes on the COSTWAY, such as sleep and auto, give you more flexibility for different situations. You can select the sleep mode for quieter nighttime operation or use auto mode for automated adjustments. The COSTWAY has more options for customization, giving it the edge in this category.
Fan Speeds
Edge: COSTWAY 12000 BTU Mini Split 17 SEER2
Fan speeds control how quickly air is circulated in your room. The Rellytech features four fan speeds: high, medium, low, and auto. The COSTWAY offers five fan speeds: low, mid, high, turbo, and auto. The inclusion of a turbo mode on the COSTWAY allows for faster cooling or heating when you need rapid temperature changes. The Rellytech’s four speeds are sufficient for general comfort, but the extra speed on the COSTWAY provides more granular control. If you prefer having an extra option for high-velocity airflow, the COSTWAY is the better choice. This gives it a slight advantage in fan speed variety.
Control Method
Edge: Tie
Both units come with remote controls for adjusting settings from a distance. The COSTWAY remote has an effective control distance of 26 feet, allowing you to adjust modes, speeds, timer, and swing from across the room. The Rellytech data does not specify the remote control distance, so we cannot compare the range directly. However, both units allow you to switch between Celsius and Fahrenheit and adjust the 4D airflow swing. Without specific data on the Rellytech’s remote range, we cannot declare a clear winner. Both provide standard remote functionality for everyday use.
Which Mini Split Fits Your Needs
Large room owners seeking max efficiency
Our pick: Rellytech 18000 BTU 230V Mini Split
You need cooling for spaces up to 1,250 square feet. This Rellytech unit delivers 18,000 BTU of cooling power with a 19 SEER2 rating. The higher efficiency rating helps manage energy use in larger areas. It also provides 18,400 BTU of heating. The 230V voltage supports robust performance for bigger rooms like offices or garages.
Small space users wanting quiet operation
Our pick: COSTWAY 12000 BTU Mini Split 17 SEER2
You are cooling a room up to 750 square feet. This COSTWAY model runs at just 23 dB for very quiet performance. It includes 12,000 BTU of cooling and 12,300 BTU of heating. The sleep mode and display off function ensure minimal disturbance. The 17 SEER2 rating still offers solid efficiency for smaller living spaces.
Buyers needing flexible airflow modes
Our pick: COSTWAY 12000 BTU Mini Split 17 SEER2
You want precise control over your environment. This unit offers seven operating modes and five fan speeds, including turbo and auto. It features 4D airflow swing to direct air exactly where you need it. The remote control works up to 26 feet away. This level of customization suits users who prefer tailored comfort settings.
Users prioritizing extreme weather durability
Our pick: COSTWAY 12000 BTU Mini Split 17 SEER2
You live in an area with very hot or cold temperatures. This COSTWAY model includes chassis electrical heating for the outdoor unit. It can cool effectively at 118.4°F and heat at 5°F. The auto defrost feature keeps winter performance ice-free. This design ensures reliable operation even during extreme weather conditions.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | Rellytech 18000 BTU 230V Mini Split | Large rooms with 230V power | |
| 2 | COSTWAY 12000 BTU Mini Split 17 SEER2 | bedrooms and small living spaces |
Rellytech 18000 BTU 230V Mini Split
Best for: Large rooms with 230V power
- SEER Rating
- 19 SEER2
- Cooling Capacity
- 18,000 BTU
- Coverage Area
- up to 1,250 sq. ft.
- SEER2 Rating
- 19
- Voltage
- 208-230V
- Operating Modes
- cooling, heating, fan, dry, ECO
This Rellytech mini split delivers 18,000 BTU of cooling and 18,400 BTU of heating for spaces up to 1,250 square feet. It runs on 230V power and carries a 19 SEER2 rating with an HSPF2 of 8.5. The unit includes four fan speeds and a 90-degree vertical swing. You get four operating modes, including a smart ECO function for efficient temperature control. It is designed for year-round comfort in bedrooms or offices.
- High 19 SEER2 energy efficiency rating
- 18,000 BTU cooling and 18,400 BTU heating capacity
- 4 fan speeds with 90-degree vertical swing
- Smart ECO mode for optimized energy use
- Heavier build at 112 pounds
- Larger footprint with a 39.6-inch width
- Fewer operating modes than premium inverter models
- You need strong cooling for a 1,250 sq. ft. room
- You have a 230V electrical outlet available
- You want high energy efficiency with a 19 SEER2 rating
- You only have 115V power outlets
- You need a unit under 100 pounds for easy installation
- You require a width smaller than 39.6 inches
Verdict: Rellytech 18000 BTU 19 SEER2 Mini Split suits you if you need powerful heating and cooling for a large room with 230V power. Its high SEER2 rating ensures lower energy use, though the heavy and wide unit requires sturdy mounting.
COSTWAY 12000 BTU Mini Split 17 SEER2
Best for: bedrooms and small living spaces
- SEER Rating
- 17 SEER2
- Cooling Capacity
- 12000 BTU
- Coverage Area
- 750 sq ft
- SEER2 Rating
- 17 SEER2
- Voltage
- 208-230V
- Smart Compatibility
- Remote control
This COSTWAY mini split delivers 12,000 BTU of cooling and 12,300 BTU of heating. It carries a 17 SEER2 rating for cooling efficiency. The unit covers spaces up to 750 square feet. It operates quietly at 23 dB. You get seven operating modes and five fan speeds. The outdoor unit withstands temperatures from 5°F to 118.4°F. This model suits those prioritizing quiet operation and reliable heating in moderate climates.
- 17 SEER2 cooling efficiency rating
- Ultra-quiet 23 dB operation
- Heats effectively down to 5°F
- 7 operating modes including ECO and sleep
- Self-cleaning function at 137°F
- 17 SEER2 is lower than the 19 SEER2 on this list
- 12,000 BTU capacity is smaller than the 18,000 BTU option
- 230V voltage limits placement to specific circuits
- You need quiet operation for a bedroom
- You want reliable heating in cold weather
- You have a 230V circuit available
- You need the highest efficiency rating available
- You require more than 12,000 BTU
- You only have 115V outlets
Verdict: COSTWAY 12000 BTU Mini Split offers solid heating and quiet cooling for smaller rooms. It fits buyers who value low noise and dependable winter performance over maximum energy efficiency.
Specifications side by side
| Spec | Rellytech 18000 BTU 230V Mini Split | COSTWAY 12000 BTU Mini Split 17 SEER2 |
|---|---|---|
| Cooling Capacity | 18,000 BTU | 12000 BTU |
| Coverage Area | up to 1,250 sq. ft. | 750 sq ft |
| SEER2 Rating | 19 | 17 SEER2 |
| Voltage | 208-230V | 208-230V |
| Smart Compatibility | – | Remote control |
| Operating Modes | cooling, heating, fan, dry, ECO | Cool, heat, dry, fan, auto, sleep, ECO |
| Features | Inverter | Inverter |
| Color | White | White |
| Operating Mode | – | Heater |
| SEER Rating | 19 SEER2 | 17 SEER2 |
| Dimensions | 9.02 × 40.4 × 12.6 inches | 11.5 × 31.2 × 7.91 inches |
| Weight | 112 pounds | 17.6 pounds |
| Size | 18000BTU,230V,19 SEER2 | 12000BTU, 208-230V, 17 SEER2 |
| Model | CE0-1 | 11090-CYFP |
Frequently asked questions
Is 19 SEER2 significantly more efficient than 17 SEER2?
Yes, a 19 SEER2 rating indicates higher energy efficiency than 17 SEER2. This means the unit converts more electricity into cooling or heating output. You will likely see lower energy consumption for the same amount of climate control. The Rellytech model demonstrates this with its 19 SEER2 rating compared to the COSTWAY's 17 SEER2.
What is the difference in cooling power between these units?
The Rellytech unit provides 18,000 BTU of cooling power. The COSTWAY model offers 12,000 BTU. Higher BTU means the Rellytech can cool larger spaces more quickly. You should choose the 18,000 BTU model for rooms up to 1,250 square feet. The 12,000 BTU unit is better for smaller areas.
Do both mini splits use inverter technology?
Yes, both listed models use inverter technology. This feature allows the compressor to adjust its speed rather than turning on and off. It provides more stable temperatures and reduces energy waste. You get smoother operation and potentially longer component life with inverter-driven systems compared to non-inverter units.
Which unit is better for large rooms?
The Rellytech 18,000 BTU model is better for large rooms. It covers up to 1,250 square feet and delivers higher cooling capacity. The COSTWAY unit is rated for smaller spaces, up to 750 square feet. If you need to cool a large area, the higher BTU and SEER2 rating of the Rellytech make it the practical choice.
Is the 19 SEER2 unit heavier than the 17 SEER2?
Yes, the 19 SEER2 Rellytech unit weighs 112 pounds. The 17 SEER2 COSTWAY model weighs only 17.6 pounds. The significant weight difference reflects the larger size and power of the Rellytech unit. You will need sturdy mounting hardware for the heavier 18,000 BTU model. The lighter unit is easier to handle during installation.
Do both models support heating mode?
Yes, both units support heating mode. The Rellytech and COSTWAY models are designed to provide warmth during colder months. You can use them as heat pumps to maintain comfortable indoor temperatures year-round. This dual functionality makes them versatile solutions for climate control in various seasons.