Bosch T9800 SE 199

The figure of 178 therms does not come from the registry as a printed value. This site computed it from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.95 for this model, and from the DOE test's daily hot-water draw for the high draw pattern. The source is the DOE CCD, retrieved 2026-09-19. The condition matters: the figure applies only at the federal test's daily draw, so a home that uses more or less hot water will use different energy. The maximum flow rate in gallons per minute is 5.4. It is not an input to the annual figure, which uses only UEF and the daily draw. The steps are set out in how the annual cost is calculated.

Among the 397 models registered as a gas tankless unit at the high draw pattern, this one ranks 45th lowest in energy use. That places it in the lowest quarter of its class. The class median is 182 therms, and this model sits 4 therms below it, measured at the high draw pattern only. The high draw pattern describes a larger household, or one where showers and laundry overlap, so the figure is most relevant to those homes. It says little about a household with much lighter daily use, and this page has no figure for other draw patterns on this model. To compare against another unit in the same class, you can find a same-class replacement by model number.

The running cost is not written in the text, because it depends on your state's average residential gas price. To apply 178 therms to your own rate, use the cost calculator on your own ZIP. The 4 therms gap to the class median also converts to a cost only at that same rate. The registry data does not include measured use in any actual home, so the figure is a calculation at the federal test's draw, not a reading. The modeled installed-cost range is shown in its own block with its source and date. It is a range, not a quote, and it is not repeated here. If fuel, space or size differ from your case, the selector by fuel, space and size covers those inputs.