The newest addition to the company’s ecoTough series of gas-fired condensing tankless water heaters, NRC98 has an energy factor of 0.93, which is almost 10 points higher than a conventional tankless unit. The product offers a maximum flow rate of 9.8 gallons per minute and a standard BTU range of 16,000 to 180,000. Cost: $2,349.Noritz America