Lennox WHGS040T40NPXS****

It holds 38 gallons in the test, 2 gallons less than its 40-gallon sold size. Starting full, it gives 78 gallons of hot water in its first hour of use. Reheating lets it give 40 gallons beyond the 38 gallons in its tank. Of 763 gas storage models, 366 give more hot water in the first hour. The median gas storage model gives the same amount in its first hour.

As of Oct 26, 2026, it was not listed as ENERGY STAR certified. In tests, 70% of the energy it uses ends up as hot water (UEF 0.70). In the test, daily hot water use was set to high (its draw pattern). Among 434 gas storage models on its draw pattern, 111 have a higher UEF. For its type and draw pattern, the median UEF is 0.66. The water took in 80% of the energy used to reheat it (its recovery efficiency).

There are 3 more basic models with the same test figures. Of those, one or more are under the AMERICAN STANDARD WATER HEATERS and Ariston brands. For the full group, see the AMERICAN STANDARD WATER HEATERS PV40TLN*.

It may qualify for 2 rebate programs in 2 states.