Lennox WHHP065T45MD240S****

It holds 61 gallons in the test, 4 gallons less than its 65-gallon sold size. Starting full, it gives 77 gallons of hot water in its first hour of use. That is 16 gallons more than its tank holds, since it reheats during the hour. Of 481 heat pump models, 181 give more hot water in the first hour. Among heat pump models, the median first-hour rating is 72 gallons.

Its single model number, WHHP065T45MD240S****, is ENERGY STAR certified. For each unit of energy it uses, 4.05 units end up in the hot water (its UEF). Pulling heat from the air lets its UEF pass 1. The daily hot water use in the test, called its draw pattern, was high. Of 237 heat pump models with the same draw pattern, 32 have a higher UEF and 172 a lower one. A UEF of 3.88 is the median for its type and draw pattern. When it reheats water in the test, the water gains 446% of the energy it uses.

All of its test figures are shared by one other basic model. That one is listed under the Ariston brand. You can find the whole group on the page for the Ariston ARIHPWH-65-T.

In 19 states, 20 rebate programs may accept it. Another 7 programs may accept it if it meets their other terms.