JOHN WOOD T-H3M-DV-N 1**

The registry lists its UEF, the ratio of hot water delivered to energy used, as 0.9 in the federal test. This site computed 123 therms from that UEF and the DOE test's daily hot-water draw for the medium draw pattern. The registry does not publish the annual figure itself. The source is DOE CCD, retrieved 2026-09-19. The class is the 80 models registered as a gas tankless unit at the medium draw pattern. This unit has the 10th lowest energy use of 80, which is in the lowest quarter of its class. Its 123 therms is 12 therms below the class median of 135 therms.

This figure suits a check against a household whose hot-water use resembles the medium draw pattern. It is a modeled value, not a measurement of any one home. The registry lists a maximum flow rate in gallons per minute of 3.3. The temperature rise behind that flow is not available here, so the flow figure alone does not show how many fixtures the unit can serve at once. The 123 therms does not carry over to other households. The annual energy for other draw patterns is not available on this page. The comparison with 135 therms holds only inside this class of 80 models.

The running cost is not stated in the text. It depends on your state's average residential gas price. Enter your ZIP in the cost calculator to apply that price to 123 therms. The methodology page explains how the annual cost is calculated. The same 123 therms costs more where gas is priced higher and less where it is priced lower. If you need a unit in the same class, you can find a same-class replacement by model number. The modeled installed-cost range appears in its own block on this page, with its source and date.