RELIANCE WATER HEATERS FMDV-40 2**

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.59 for the FMDV-40 2**. This site combines that value with the federal test's daily hot-water draw for the medium draw pattern, which represents a typical three- or four-person household. The result is 188 therms of natural gas a year, from DOE CCD data retrieved 2026-09-19. The registry does not publish this annual figure; it is this site's calculation. It holds only at the test's daily draw, so a household that draws more or less hot water will use a different amount. The methodology page explains how the annual cost is calculated from it.

Among the 288 models registered as a gas tank at the medium draw pattern, this model ranks 186th lowest in energy use. The class median is 185 therms, and this model sits 3 therms above it, in the second-highest quarter of its class for energy use. That comparison uses annual energy only. The model has a first hour rating, the gallons of hot water available in the first hour from a full tank, of 57 gallons, and a rated volume of 38 gallons. The annual figure applies to households whose use matches the medium draw pattern. It says little about a household with a larger or smaller daily draw. Such a household can use the water heater selector to filter by fuel, space and size.

The running cost is not stated here because it depends on the state average residential gas price, which differs by reader. The cost calculator applies the rate for your ZIP to the 188 therms listed for this model at the medium draw pattern. The modeled installed-cost range appears in its own block on this page with its source and date; it is a modeled range, not a quote. To compare this model with another in the same class, the replacement finder works from a model number, and both models are then measured against the same class median of 185 therms.