RINNAI V53DE (REU-AM1620WD-US)

The figure of 137 therms is computed by this site, not published by the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, of 0.81 with the DOE test's daily hot-water draw for the medium draw pattern. The result applies only to that draw and to natural gas. A household that draws more or less hot water than the federal test will use a different amount. The energy data comes from the DOE CCD, retrieved 2026-09-19. The calculation is set out in how the annual cost is calculated.

Among the 80 models registered as a gas tankless unit at the medium draw pattern, this unit ranks 52nd lowest for energy use, in the second-highest quarter of its class. Its 137 therms is 2 therms above the class median of 135 therms. That makes it useful for a reader who wants to confirm where this model sits against its own class at this draw. It does not help a reader comparing another fuel or another draw pattern, because the rank holds only for this class. The registry lists a maximum flow rate in gallons per minute of 3; the condition behind that value is not stated in the data used here. To look for a unit in the same class, use find a same-class replacement by model number.

The running cost is not written here because it depends on the state average residential gas price for the reader's ZIP. Multiplying 137 therms by a local price per therm gives the yearly gas cost at the medium draw pattern, and the cost calculator on your own ZIP does this with the state average. A household whose hot-water use differs from the federal test's daily draw will see a different total. The installed cost is a separate matter and appears in its own block with its source and date. If fuel, space or size limits the choice, the water heater selector by fuel, space and size filters by those limits. A measured usage figure for this model is not available in the registry.