Aquastar 38B tankless water heater is compatible with solar and wood heating systems and can run on natural gas or propane. Weighing in at 25lbs, this water heater measures 25 3/8" x 10 5/8" x 9 1/8" has a water pressure range of 18 to 150 psi. Minimum flow rate is 0.6 gallons per minute and BTU input is 40,000. Featuring a water and gas inlet connection of 1/2" NPT, the minimum requirements for natural gas line is 1/2" NPT and minimum LP gas line is 3/8". Minimum LP gas pressure is 11" WC and minimum natural gas pressure is 7" WC. THE AQUASTAR 38B OFFERS 80% ENERGY EFFECIENCY AND AN ENERGY FACTOR OF .66!