JOHN WOOD T-H3S-DV-N 1**

The figure of 178 therms comes from this site, not from the registry. It starts from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.95. It then applies the DOE test's daily hot-water draw for the high draw pattern. The source is DOE CCD, retrieved 2026-09-19. Against the 397 gas tankless models registered at the high draw pattern, this unit sits 4 therms below the class median of 182 therms. That places it 45th lowest for energy use, in the lowest quarter of its class. The steps behind the calculation are set out in how the annual cost is calculated.

The high draw pattern describes a larger household, or one where showers and laundry overlap. The 178 therms figure applies to that pattern only, and this page holds no figure for other draw patterns. Real use in a home can differ from the federal test's daily draw, and this page does not measure it. The registry also lists a maximum flow rate in gallons per minute of 5.4. This record does not show whether that flow covers a given home's simultaneous use, so no judgment is made. To compare options by fuel, space and size, use the selector by fuel, space and size. To look for a unit in the same class, 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, which differs by reader. That price is applied to the 178 therms figure once your ZIP is known. The cost calculator on your own ZIP does this for this model. The same price also applies to the 4 therms gap from the class median of 182 therms, so the cost of that gap follows the price as well. The modeled installed-cost range appears in its own block on the page, with its source and date. It is a modeled range, not a quote, and it is not restated here. Energy data was retrieved 2026-09-19, so later registry changes are not reflected.