RELIANCE WATER HEATERS ATHR-160M 1**

The 178 therms figure is computed by this site, not published by the registry. It combines the model's UEF, the ratio of hot water delivered to energy used, of 0.95 with the DOE test's daily hot-water draw for the high draw pattern. The UEF comes from the DOE CCD, retrieved 2026-09-19. So the figure describes the federal test's usage, not the usage of any particular home. Among the 397 gas tankless models registered at the high draw pattern, this unit ranks 45th lowest in energy use. That places it in the lowest quarter of its class. The gap to the class median of 182 therms is 4 therms a year at the test's draw.

The high draw pattern describes a larger household, or one where showers and laundry overlap. The 178 therms figure applies to that usage only. A home that draws less hot water than the test assumes would use a different amount, and this page has no figure for other draw patterns. The model's maximum flow rate in gallons per minute is 4.8. Demand above 4.8 at one time is outside what that rating covers. To compare units by fuel, space and size, use the water heater selector by fuel, space and size. To check an alternative in the same class, you can find a same-class replacement by model number.

The running cost of 178 therms of natural gas is not stated in this text. It depends on your state's average residential gas price, so the page computes it from your ZIP. Enter it in the running-cost calculator for your own ZIP. The method behind the annual cost figure sets out how the energy figure and the gas price combine. The 4 therms gap to the class median carries into that calculation at your own rate. The page cannot say what it comes to without that rate. The installed price shown in its own block is a modeled range with its source and date, not a quote.