Navien's line of tankless water heaters relies on super-efficient condensing gas burners to create an endless supply of domestic hot water. Because condensing burners extract 98 percent of the heat from the gas flame, operating costs are less than one-half of an average tankless water heater and one-third of traditional tank heaters. And the exhaust is so cool, heaters can be vented with plastic pipe. The Model A shown has a miniature buffer tank to keep the hot water coming even when the flow is reduced to a trickle. The largest models have maximum flow rates of 11 gallons per minute in warm climates, 6 gpm in cold climates.
About $1,300 to $2,000; Navien