Featuring a power vented flue this tankless water heater uses sealed combustion and is fully modulated, making it perfect for domestic hot water systems. It can also be used with water storage tanks, recirculation systems, hydronic heating systems, radiant floor heating systems, and/or combined domestic & heating applications while complying with Ultra-Low NOx regulations, lead free standards, and being Energy Star® Qualified. Features: Energy Star Qualified Overheat Cutoff Fuse and Built-in Freeze Protection Efficient, Durable and Easy to Install Stronger than Standard Copper and More Resilient Against Erosion Complies with Lead Free Standards Includes Built-in Temperature Controller and Diagnostics 3 or 4 Inch Venting Up to 8 Gallons Per Minute Acceptable for up to 4 Showers Electric Ignition HRS35 copper is an alloy that is 99.5% pure copper with a .5% mixture of other elements, this alloy is much stronger and harder than the standard C1220, which is the copper. HRS35 has 8 times the tensile strength of standard copper Energy Star is an international standard for energy efficient consumer products originated in the United States of America. It was created in 1992 by the Environmental Protection Agency and the Department of Energy. Devices carrying the Energy Star service mark, such as computer products and peripherals, kitchen appliances, buildings and other products, generally use 20%–30% less energy than required by federal standards. Following the South Coast Air Quality Management District (AQMD), several other AQMDs have adopted regulations to require residential water heater (<75,000 Btu/hr heat input) NOx emission to be less than 10 nanograms per joule of heat output. The South Coast AQMD also requires that tankless water heaters to have NOx emission less than less than 14 nanograms per joule of heat output or less than or equal to 20 ppm (at 3% O2, dry). Specifications: 20.5 Inch Height 13.8 Inch Width 8.5 Inch Depth Weight: 40 Pounds Energy Factor: .82 BTU: 15,000-190,000 Gas and Water Connections: 3/4 NPT Water Pressure: 15-150 PSI 120V AC Nominal Dimensions: 13-4/5 (W) x 8-1/2 (D) x 20-1/2 (H) Why choose Takagi? Takagi produce some of the most highly efficient tankless water heaters in the industry. With a commitment to innovation and quality, they are constantly creating new technology to keep up with their customers’ ever-changing hot water needs. Takagi sets the bar with the most stringent of durability testing standards for all of our models. For 15 years, Takagi has provided the most eco-friendly, energy-efficient water heating solutions in North America.