When compared to gas type tankless water heaters, Stiebel Eltron Tempra 15B, cost less and is less expensive to install, since it does not require venting parts. While gas type tankless water heaters with outside venting may have a 5-20% efficiency reduction (due to heat loss from gases escaping through the vent), Stiebel Eltron Tempra 15B is designed to be virtually 100% efficient. Multiple heating elements inside the Tempra 15B models activate as the water demand increases, thus providing maximum efficiency and complete comfort. Specs: Product Specs Width: 14-9/16" Flow Rate: 0.58-3 GPM Amperage: 60 Wattage: 14400 Heating Capacity: 1-2 Bathrooms Height: 14-1/2" Application: Plumbing Voltage: 240v, 208v Depth: 4-5/8" Type: Electric Efficiency: 0.99% Water Connection: 3/4" Temperature Range (F): 86-140 F