The Atmor thermopro tankless water heater revolutionizes water heating with self modulating technology that provides unlimited hot water when you need it, without the wait. Advanced technology regulates the amount of energy required to heat the water. This delivers major savings on energy bills and lowers water consumption. The easy-to-use digital panel allows full control with the power to make temperature adjustments down to the exact degree for the perfect water temperature. Compact, space-saving design requires no venting and can be installed anywhere inside your home or garage. Unit is IP54 certified to keep internal components safe and dry. Durable and corrosion resistant stainless steel interior assembly allow for heating efficiency and longer life expectancy. The 27Kw/240V, 5.1 gpm capacity is ideal for small to medium sized homes that will be running up to 4 applications at once, such as: 2 Showers (1.5 gpm/shower head), 1 kitchen sink (1 gpm), and 1 bathroom sink (.5 gpm) at inlet temperatures of 73 degrees F. Colder climates that require a higher temperature rise will reduce the amount of applications and GPM (gallons pers minute). Choosing the right tankless heater depends on your incoming water temperature, flow rate, number of applications and your desired output temperature. Your incoming water temperature (also called inlet temperature) varies by location and seasonality. Colder inlet water temps require a much higher temperature rise. For additional info and help choosing a model, please see our selection guide below or call our support team at 888.783.6082.