STATE DURABILITY ON-DEMAND. MODEL SPECIFICATIONS Model Number BTU Input Natural / Propane Minimum Maximum Hot Water Output (GPM) Maximum 45º F Rise 77º F Rise Approximate Shipping Weight (lbs) INTERIOR MODELS GTS-305-NI 15,000 199,000/190,000 5.3 5.3 4.2 50 GTS-505-NI 15,000 199,000/190,000 8.5 7.4/7.1 4.2 50 GTS-705-NI 19,000 237,000 9.8 8.8 5.1 55 GTS-705-NIA* 19,000 237,000 9.8 8.8 5.1 55 For propane, change “N” to “P” in model number (GTS 305-PI).