Takagi T-K3 tankless water heater is compatible with solar hot water systems as well as natural gas and propane. Weighing in at 40lbs, this water heater measures 20.5" x 13.8" x 8.5" and starts with an electronic ignition and a AC 120 V power supply. Featuring 3/4" NPT water and gas connections, water pressure from 15 to 150 psi, this heater requires a natural gas input or LPG input of 11,000 BTU and a maximum of 199,000 BTU. Natural gas pressure inlet minimum of 5" WC and a maximum of 10.5 WC. LP gas pressure inlet minimum of 8" WC and maximum of 13.5" WC. Manifold pressure for natural gas is 2.5" WC and for propane the rating is 4.4" WC. ONE OF THE MOST POWERFUL AND ENERGY EFFECIENT TANKLESS WATER HEATERS ON THE MARKET!