Ariston PV40TLN*

It holds 38 gallons in the test, 2 gallons less than its 40-gallon sold size. Over one hour from a full tank, it gave 78 gallons in the test (its first-hour rating). That is 40 gallons more than its tank holds, since it reheats during the hour. In the first hour, 366 of the 763 gas storage models give more hot water. In first-hour rating, it ties the median gas storage model.

It was not listed as ENERGY STAR certified on Oct 26, 2026. In tests, 70% of the energy it uses ends up as hot water (UEF 0.70). The daily hot water use in the test, called its draw pattern, was high. Of 434 gas storage models with the same draw pattern, 111 have a higher UEF and 283 a lower one. For its type and draw pattern, the median UEF is 0.66. Of the energy spent to reheat water, 80% goes into it (its recovery efficiency).

Its 2 model numbers are GSPV40T40* and GSPV40T50*. There are 3 more basic models with the same test figures. Of those, one or more are under the AMERICAN STANDARD WATER HEATERS and Lennox brands. You can find the whole group on the page for the AMERICAN STANDARD WATER HEATERS PV40TLN*.

In 2 states, 2 rebate programs may accept it.