KUSUB421A
LG · HP - Mini or Multi Split
ENERGY STAR CertifiedAir-Source Heat Pumps →
SEER2
18.5BTU/Wh
HSPF2
9.5BTU/Wh
Cooling Capacity
42000BTU/hr
Cold Climate
Yes
Cold climate certified
ENERGY STAR Most Efficient
LG KUSUB421A: SEER2 18.5 BTU/Wh, around the middle of the range for air-source heat pumps (category median 20 BTU/Wh).
Where this model sits
Cooling42000BTU/hr
6000median 2400060000
SEER218.5BTU/Wh
15.2median 2035.1
The LG KUSUB421A is a 42000 BTU/hr hp - mini or multi split using R-32, a refrigerant with moderate global warming potential (GWP 675). At 18.5 BTU/Wh it ranks around the middle of the 12,218 certified air-source heat pumps models. Among similar-sized air-source heat pumps (within 10% of its size), it is more efficient than the peer median of 16 BTU/Wh.
Specifications
| Efficiency | |
|---|---|
| SEER2 (best combination) | 18.5BTU/Wh |
| SEER2 (worst combination) | 18.5BTU/Wh |
| HSPF2 (best combination) | 9.5BTU/Wh |
| HSPF2 (worst combination) | 9.5BTU/Wh |
| EER2 (best combination) | 11BTU/Wh |
| COP at 5 °F | 1.85 |
| Capacity | |
| Cooling Capacity (max) | 42000BTU/hr |
| Cooling Capacity (min) | 42000BTU/hr |
| Heating at 47 °F | 46000BTU/hr |
| Heating at 17 °F | 29000BTU/hr |
| Heating at 5 °F | 36800BTU/hr |
All 25 specifications
| Configuration | |
|---|---|
| Product Type | HP - Mini or Multi Split |
| Compressor Staging | Continuously variable |
| Cold Climate Certified | Yes |
| Connected Capability | No |
| Series | KUSUB421A |
| Indoor-Unit Combinations Rated | 1 |
| Refrigerant | |
| Type | R-32 |
| GWP Rating | R-32 (GWP:675 | Lower GWP) |
| Identifiers | |
| Model Number | KUSUB421A |
| ENERGY STAR ID | ES_1118034_KUSUB421A_04292026233000_29218426765 |
| Partner | LG Electronics, Inc. |
| Date Certified | 2026-05-06 |
| Available From | 2026-04-30 |
| Markets | United States, Canada |
Documentation
We link to manufacturer documentation at its original source rather than rehosting it, so you always get the current revision.