Short answer (updated November 1, 2026)
A heat pump water heater works year-round in a basement and in a garage that stays mild. Most integrated heat pump water heaters run their compressor down to about 37°F surrounding air; below that they switch to backup electric heating (or stop heating, on some 120V models). The lowest rated cutoff among integrated units is 23°F (LG R5TT20F-SA0 (208V)), and split systems with an outdoor compressor go as low as -26°F. Every integrated model's cutoff is at or below 45°F, so a basement that stays above that works year-round with any of them. An unheated garage works in mild climates; in cold-winter states, expect the unit to run on resistance backup in the coldest weeks.
Minimum operating air temperature by model
Integrated (all-in-one) models, lowest cutoff first. Showing the first 60 of 140 distinct models. Distribution of cutoffs across all 140: 23°F (6), 35°F (38), 36°F (2), 37°F (84), 40°F (1), 41°F (3), 45°F (6).
| Model | Type | Gallons | Min. air temp | UEF | kWh/yr | Noise |
|---|---|---|---|---|---|---|
| LG R5TT20F-SA0 (208V) + 1 variant | 240V | 52 | 23°F | 3.75 | 866 | — |
| LG APHWC502D + 2 variants | 240V | 53 | 23°F | 4.20 | 1,181 | — |
| LG APHWC501D + 1 variant | 240V | 53 | 23°F | 3.93 | 1,262 | — |
| LG APHWC501M | 240V | 53 | 23°F | 3.93 | 1,262 | 42 dBA |
| LG APHWC801D + 1 variant | 240V | 72 | 23°F | 3.90 | 1,272 | — |
| LG APHWC801M | 240V | 72 | 23°F | 3.90 | 1,272 | 42 dBA |
| GE Profile PF40S10FPY01 + 1 variant | 120V plug-in | 40 | 35°F | 3.10 | 724 | 41 dBA |
| GE Profile PH40S10BPY01 | 240V | 40 | 35°F | 4.20 | 773 | 41 dBA |
| GE Profile PK50S10FNY01 | 240V | 50 | 35°F | 4.20 | 773 | 41 dBA |
| GE Profile PK65S10FNY01 | 240V | 65 | 35°F | 4.10 | 792 | 41 dBA |
| Ariston ARIHPWH-50-T + 2 variants incl. AMERICAN STANDARD WATER HEATERS, Lennox | 240V | 45 | 35°F | 3.83 | 848 | — |
| Ariston ARIHPWH-50 + 1 variant incl. AMERICAN STANDARD WATER HEATERS | 240V | 45 | 35°F | 3.75 | 867 | — |
| Ariston ARIHPWH-40 + 1 variant incl. AMERICAN STANDARD WATER HEATERS | 240V | 37 | 35°F | 3.58 | 907 | — |
| Ariston ARIHPWH-40-T + 2 variants incl. AMERICAN STANDARD WATER HEATERS, Lennox | 240V | 37 | 35°F | 3.55 | 915 | — |
| Noritz NHP50 + 3 variants incl. Hubbell, VAUGHN THERMAL | 240V | 47 | 35°F | 3.46 | 938 | 54 dBA |
| Bradford White RE2H50S | 240V | 45 | 35°F | 3.44 | 944 | 51 dBA |
| JETGLAS RE2H50S | 240V | 45 | 35°F | 3.44 | 944 | — |
| AMERICAN STANDARD WATER HEATERS ASHPWH-40-B | 240V | 37 | 35°F | 3.40 | 955 | — |
| Noritz NHP65 + 3 variants incl. Hubbell, VAUGHN THERMAL | 240V | 57 | 35°F | 3.34 | 974 | 54 dBA |
| VAUGHN THERMAL MP55FHPT | 240V | 55 | 35°F | 3.30 | 982 | 54 dBA |
| GE Profile PF50S10FPY01 (no longer made) + 1 variant | 120V plug-in | 50 | 35°F | 3.20 | 1,015 | 41 dBA |
| GE Profile PH50S10BNY01 | 240V | 50 | 35°F | 4.50 | 1,102 | 41 dBA |
| GE Profile PH80S10BNY01 | 240V | 80 | 35°F | 4.50 | 1,102 | 41 dBA |
| GE Profile PK80S10FNY01 | 240V | 80 | 35°F | 4.50 | 1,102 | 41 dBA |
| GE Profile PH80S10BPY01 (no longer made) | 240V | 80 | 35°F | 4.40 | 1,127 | 41 dBA |
| GE Profile PH50S10BPY01 (no longer made) | 240V | 50 | 35°F | 4.30 | 1,154 | 41 dBA |
| GE Profile PH65S10BNY01 | 240V | 65 | 35°F | 4.30 | 1,154 | 41 dBA |
| GE Profile PH65S10BPY01 (no longer made) | 240V | 65 | 35°F | 4.30 | 1,154 | 41 dBA |
| Ariston ARIHPWH-80-T + 2 variants incl. AMERICAN STANDARD WATER HEATERS, Lennox | 240V | 74 | 35°F | 4.10 | 1,210 | — |
| Ariston ARIHPWH-65-T + 2 variants incl. AMERICAN STANDARD WATER HEATERS, Lennox | 240V | 61 | 35°F | 4.05 | 1,225 | — |
| Ariston ARIHPWH-80 + 1 variant incl. AMERICAN STANDARD WATER HEATERS | 240V | 73 | 35°F | 4.01 | 1,238 | — |
| Ariston ARIHPWH-65 + 1 variant incl. AMERICAN STANDARD WATER HEATERS | 240V | 62 | 35°F | 3.85 | 1,289 | — |
| AMERICAN STANDARD WATER HEATERS ASHPWH-80-B | 240V | 73 | 35°F | 3.83 | 1,297 | — |
| AMERICAN STANDARD WATER HEATERS ASHPWH-65-B | 240V | 62 | 35°F | 3.68 | 1,348 | — |
| Bradford White RE2H65T | 240V | 64 | 35°F | 3.64 | 1,363 | 51 dBA |
| JETGLAS RE2H65T | 240V | 64 | 35°F | 3.64 | 1,363 | — |
| VAUGHN THERMAL MP80FHPT | 240V | 80 | 35°F | 3.50 | 1,375 | 54 dBA |
| Bradford White RE2H80T | 240V | 75 | 35°F | 3.59 | 1,382 | 51 dBA |
| JETGLAS RE2H80T | 240V | 75 | 35°F | 3.59 | 1,382 | — |
| GE Profile PF80S10FPY01 (no longer made) + 1 variant | 120V plug-in | 80 | 35°F | 3.50 | 1,417 | 41 dBA |
| VAUGHN THERMAL MP120FHPT | 240V | 119 | 35°F | 3.50 | 1,418 | 54 dBA |
| Noritz NHP80 + 3 variants incl. Hubbell, VAUGHN THERMAL | 240V | 74 | 35°F | 3.48 | 1,424 | 54 dBA |
| GE Profile PF65S10FPY01 (no longer made) + 1 variant | 120V plug-in | 65 | 35°F | 3.40 | 1,459 | 41 dBA |
| Noritz NHP120 + 3 variants incl. Hubbell, VAUGHN THERMAL | 240V | 109 | 35°F | 3.38 | 1,467 | 54 dBA |
| GREE GRS-3.0Pd/TD70GANhA-D | 240V | 68 | 35.6°F | 4.03 | 1,233 | — |
| GREE GRS-3.0Pd/TD50GANhA-D | 240V | 55 | 35.6°F | 4.02 | 1,234 | — |
| Rheem XE40T10H22U0 + 16 variants incl. Friedrich, Richmond, Ruud | 240V | 36 | 37°F | 3.45 | 643 | — |
| A. O. Smith HPS10-50H45DV-2 + 5 variants incl. American, Lochinvar, RELIANCE WATER HEATERS | 240V | 46 | 37°F | 3.80 | 831 | — |
| A. O. Smith HPTS-50-2 | 240V | 46 | 37°F | 3.80 | 831 | 45 dBA |
| Bradford White RE2HP50-1NCTT | 240V | 45 | 37°F | 3.89 | 835 | 51 dBA |
| JETGLAS RE2HP50-1NCTT | 240V | 45 | 37°F | 3.89 | 835 | — |
| Richmond 10CE50-HP5S30 | 240V | 45 | 37°F | 3.88 | 837 | — |
| Rheem HPLD50-1RH + 39 variants incl. Friedrich, Richmond, Ruud | 240V | 45 | 37°F | 3.88 | 846 | — |
| Rheem XE50T10H22U0 + 16 variants incl. Friedrich, Richmond, Ruud | 240V | 45 | 37°F | 3.75 | 846 | — |
| Rheem PROPH50 T2 RH400-30 | 240V | 45 | 37°F | 3.88 | 846 | 49 dBA |
| Rheem HPLD40-1RH + 37 variants incl. Friedrich, Richmond, Ruud | 240V | 36 | 37°F | 3.83 | 859 | — |
| Rheem PROPH40 T2 RH400-30 | 240V | 36 | 37°F | 3.83 | 859 | 49 dBA |
| Rheem XE80T10H22U0 + 16 variants incl. Friedrich, Richmond, Ruud | 240V | 72 | 37°F | 3.70 | 871 | — |
| Rheem ECE H40 T2 RH310BM + 15 variants incl. Friedrich, Ruud | 240V | 36 | 37°F | 3.50 | 879 | — |
| A. O. Smith HPA10-50H45DV-2 + 3 variants incl. Lochinvar, RELIANCE WATER HEATERS, State | 240V | 46 | 37°F | 3.68 | 883 | — |
Garage, basement, or utility room?
Basement: usually the best location. Temperatures are stable, there is plenty of air volume, and the cooling and dehumidifying side effect is often welcome. Garage: fine in mild climates and in summer everywhere. In winter, a garage that drops below the cutoff means the unit runs on its resistance element, which costs three to four times as much per gallon of hot water. Insulated, attached garages do better than detached ones. Utility room or closet: needs enough air volume (about 700 cubic feet for most models) or a louvered door or duct kit, and it will cool the space around it.
States with the coldest winter inlet water (which also signals colder basements and garages): North Dakota (30°F), Minnesota (31°F), Wisconsin (32°F), Maine (33°F), Vermont (33°F), Alaska (34°F).