STATE ACTH-199M-(N,P) 1**

This site computed the 178 therms figure; the registry does not list it. The calculation combines the registry's UEF, the ratio of hot water delivered to energy used, with the DOE test's daily hot-water draw for the high draw pattern. For this model the UEF is 0.95. The registry data comes from the DOE CCD, retrieved 2026-09-19. The figure holds only at that federal test draw. A household that uses more or less hot water each day will use a different amount of gas. The comparison class is the 397 models registered as gas tankless units at the high draw pattern. Our method for turning registry ratings into annual energy and cost shows each step.

The high draw pattern describes a larger household, or one where showers and laundry overlap. This model's rating reflects that level of use. Its maximum flow rate in gallons per minute is 5.8. It ranks 45th lowest of 397, which puts it in the lowest quarter of its class for energy use. At the test draw, the gap to the class median is 4 therms a year. This page has no energy figure for a household with lighter daily use because the data used here does not include that value. If you are matching an existing unit, you can find a same-class replacement by model number. To compare across fuels or sizes, use the water heater selector by fuel, space and size.

This text does not state a running cost. The cost depends on your state's average residential natural gas price, so the page calculates it from your ZIP code. That calculation uses the 178 therms test-draw figure together with the gas price for your state. You can rerun it in the cost calculator for your own ZIP. The 4 therms yearly gap to the class median also depends on your rate, so its value in money differs from state to state. The installed price range appears in its own block, with its source and date. It is a modeled installed-cost range, not a quote. This page does not have gas-use figures for daily draws other than the federal test's.