The Excel Vent-Free Tankless Propane Water Heater saves energy and water while instantly delivering infinite hot water upon opening the tap, no matter the water pressure! All other tankless gas water heaters rely on outdated rubber diaphragm technology to start the units and need pressures higher than 20 PSI to operate. The Excel Tankless Propane water heater is equipped with a magnetic flow sensor that allows the unit to start up at only 2 psi water pressure. Plus, it works at up to 120 psi. Ideal for small apartments, hunting or fishing cabins, small homes, boats, campers, RVs and mobile homes. Vent-Free for Indoor or Outdoor Use. An Excel Vent-Free Water Heater can be installed indoors without cumbersome, costly flue and ductwork because it’s equipped with a state-of-the-art ODS (Oxygen Depletion Safety) shutoff device. With remarkable electronic technology that requires no standing pilot light, the Excel heater saves up to 25% in gas consumption when compared to older technology pilot light units. In case of a power outage, you can still enjoy hot water at home because it uses two (2) size “D” batteries to ignite the electronic spark module. Pure Oxygen Free Copper Heat Exchanger. Heat exchangers are devices that transfer heat to achieve desired heating or cooling. The Excel heat exchanger features Pure Oxygen Free Copper to conduct and transfer heat fast and efficiently. Pure Oxygen Free Copper has many desirable properties for durable, thermally efficient heat exchangers. Other tankless gas water heaters have regular copper heat exchangers with a tin bath. They are less efficient and have a short life. Pure copper heat exchangers are customarily used only by top-of-the-line tankless gas water heater manufacturers. Features: • Lower Gas Consumption • Indoor or Outdoor Use • Compact and Lightweight • Infinite Hot Water