MRCOOL MHWH199NCNU

This site computed the 178 therms figure; the registry does not publish it. The calculation uses the registry's UEF, the ratio of hot water delivered to energy used, and the DOE test's daily hot-water draw for the high draw pattern. The registry lists a UEF of 0.95 for this model. That value was retrieved from the DOE CCD on 2026-09-19. The figure only holds at the test's draw. A household that uses more hot water than the test assumes will burn more gas than 178 therms, and one that uses less will burn less. The registry gives no figure for this unit outside the test conditions, so that is not available here. The steps are set out in how the annual cost is calculated.

The high draw pattern stands for a larger household, or one where showers and laundry overlap. The registry lists this unit's maximum flow rate in gallons per minute as 5.7. This unit ranks 45th lowest in annual energy use among the 397 gas tankless models at the high draw pattern. That places it in the lowest quarter of its class. It uses 4 therms a year less than the class median, measured at the federal test's draw. How much that gap matters in a real home depends on how closely the home's use matches the test. To compare other units on the same registry data, the selector by fuel, space and size filters by those three factors.

The 178 therms figure does not describe a home with lower hot-water demand than the high draw pattern assumes. The class comparison above covers only the high draw pattern. The data here has no figure for this model at a smaller draw pattern. This text does not state a running cost. The cost depends on your state's average residential gas price, so the page works it out from your ZIP, using 178 therms as the input. The cost calculator on your own ZIP shows that result. If you are matching a unit, you can find a same-class replacement by model number, starting from MHWH199NCNU. The modeled installed-cost range is not a quote. It appears in its own block, with its source and date.