Ranein RH8K-LPG

The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.82 for this unit. This site computed the 135 therms figure from that UEF and the DOE test's daily hot-water draw for the medium draw pattern. The registry does not publish an annual energy value itself. The source is the DOE CCD, retrieved 2026-09-19, and the fuel is natural gas. The figure holds only at that test draw. A household that uses more or less hot water than the test assumes will use a different amount of gas, and this page has no value for those cases. The calculation is set out in how the annual cost is calculated.

This unit ranks 32nd lowest energy use of 80 in its class, which places it in the second-lowest quarter. Its 135 therms matches the class median of 135 therms, so the difference is 0 therms at the medium draw pattern. That suits a reader verifying that the listed figure is typical for a gas tankless unit at a typical household's busy-morning draw. The maximum flow rate in gallons per minute is 3.6 for this model. That is a flow rating, not an energy figure, and this page does not say whether it covers a given home's simultaneous use. For a household far from the medium draw pattern, the annual figure here does not apply; the water heater selector by fuel, space and size covers other cases.

The running cost is not written out here because it depends on the state average residential gas price, which differs by reader. The 135 therms figure is the quantity to combine with your own rate, and it applies only at the medium draw pattern. The cost calculator on your own ZIP does that step and shows the result beside the modeled installed-cost range, which is a range and not a quote. A model with a different annual figure than 135 therms would produce a different running cost at the same rate. To compare, find a same-class replacement by model number and check its energy use against this unit's 135 therms.