Mizudo FDG-CS80

The registry lists Mizudo FDG-CS80 with a UEF, the ratio of hot water delivered to energy used, of 0.81. The registry does not publish annual energy for this unit. This site computed 95 therms of natural gas a year from that UEF and the daily hot-water draw the DOE test uses for the low draw pattern. The source is DOE CCD, retrieved 2026-09-19. Among the 10 models registered as a gas tankless unit at this draw pattern, the unit ranks 7th lowest for energy use. Its figure is 2 therms above the class median of 93 therms, which places it in the second-highest quarter of its class for energy use. See how the annual cost is calculated for the method.

The figure applies to the low draw pattern, a one- or two-person household. Actual use in a household with a different draw will differ from 95 therms, and this page gives no figure for other draw patterns. The registry lists a maximum flow rate in gallons per minute of 2.1. That is the rated limit for the unit; the data here does not say how many fixtures it can serve at once. The gap of 2 therms from the class median of 93 therms is the only comparison made on this page. To compare units by fuel, space and size, use the water heater selector.

Running cost is not stated in this text because it depends on the state average residential gas price, which differs by reader. The page computes it from your ZIP, using 95 therms of natural gas at the low draw pattern. The cost calculator on your own ZIP shows the result. The installed price range appears in its own block with its source and date; it is a modeled installed-cost range, not a quote. To compare against another unit in the same class, find a same-class replacement by model number starting from FDG-CS80. The energy figure was retrieved 2026-09-19, and later registry changes are not reflected here.