The 110U Series is great for apartments, one bath homes in cold climates, condos and summer cabins. The design allows for a variety of installation options. Complies with Ultra-Low NOx regulations and meets energy efficiency requirements of ASHRAE 90.1b-1992. The GTS-110U-I tankless water heater uses up to 140000 Btu/hr of natural gas/liquid propane to deliver an endless supply of hot water for a 1.5 bath home in northern climates and up to a 2.5 bath home in southern climates (one shower head per bath). The GTS-110U-I is Energy Star® qualified with a Uniform Energy Factor of 0.81. With an industry leading 15-year limited warranty, the GTS-110U-I tankless water heater provides years of hot water through innovation and quality.