Noritz 1321 Series ASME* Certified Liquid Propane Tankless Water Heater ASME and Non-ASME Code States*PRODUCT INFORMATION:If you are looking for a tankless unit that can handle large heavy duty applications, look no further. The 1321 series can provide hot water to meet the demands of hotels, resorts and housing complexes. A single unit can produce over 13 gallons per minute. With a single system controller, you can connect up to 24 units, which is equivalent to 316 gallons per minute at 9.1 million Btus! With its stainless steel casing and ASME accreditation, no other tankless water heater on the market can match its durability and performance.Available in Natural Gas (NG) and Propane (LP) models only.Thermal Efficiency: 84%Thermal Efficiency: 84%Indoor/outdoor use*NOTE: Some states require potable water heaters to have ASME Certification. Please check all local and state codes pertaining to this device BEFORE ordering. We will not be held liable for violations or delays resulting from the installation or purchase of Non-ASME Certified Water Heaters in states with said requirement.