From the ManufacturerFor indoor installation only.The Rl94i lets you enjoy continuous hot water for up to five plumbing and appliance outlets simultaneously and always at a consistent, pre-set temperature. With a capacity of up to 9.4 gallons of hot water per minute (GPM), the Rl94i still delivers up to 40% energy savings and significant space savings. This compact, interior-mount unit vents directly to the outside with a concentric venting system. 199,000 max BTU. Product Description