NAVIEN NPE-150S2

The figure of 119 therms comes from this site, not from the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, of 0.93 with the daily hot-water draw the DOE test assigns to the medium draw pattern. That pattern represents a typical household with several people on a busy morning. The fuel is natural gas, and the source is the DOE CCD, retrieved 2026-09-19. The registry also lists a maximum flow rate in gallons per minute of 3.4 for NAVIEN NPE-150S2. That is a rated limit, separate from the annual energy figure. How the site turns these inputs into results is set out in the water heater methodology.

Against the 80 models registered as a gas tankless unit at the medium draw pattern, this model sits 16 therms below the class median of 135 therms. It ranks 2nd lowest in energy use of 80, which places it in the lowest quarter of its class. The comparison holds only at the medium draw pattern. A household whose hot-water use differs from that pattern should not read 119 therms as its own yearly use, and this page has no figure for other patterns. The unit fits a reader whose use resembles the medium draw pattern. Whether 3.4 gallons per minute covers a given home's simultaneous demand is not shown here. To compare by fuel, space and size, use the water heater selector.

Running cost is not stated in the text because it depends on the state average residential gas price, which differs from reader to reader. The calculation multiplies 119 therms by the rate that applies to the reader's ZIP, and the cost calculator for your own ZIP does this on the reader's own rate. The result holds only at the medium draw pattern, so a home with different use will see a different total. 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 look at a same-class unit, the replacement finder by model number can start from NPE-150S2.