The GT-540-PIH is well suited for residential/ commercial applications such as small restaurants and beauty salons. Complies with Ultra-Low NOx regulations. Utilizing HRS35 copper alloy for the heat exchanger tubing, the T-H3 is also suitable for heavier residential usages such as space heating or domestic recirculation systems. Remote control included as a standard feature. Certified up to 10,100 ft. altitude. ENERGY STAR® qualified 15-year limited Heat Exchanger Warranty, 5-year parts warranty, 1-year labor warranty for Residential applications Commercial Grade Copper Heat Exchanger Complies with Ultra-Low NOx regulations of less than 14 ng/J (<20ppm) Easy-Link up to four units without a Multi-Unit Controller Multi-Link up to 20 units with a Multi-Unit Controller Condensing Outdoor model Safety features include freeze, overheat, surge protection, and troubleshooting diagnostic codes