Primary commercial-grade copper heat exchanger is 25x better than stainless steel at heat transfer, stabilizing outgoing water temperatures quicker. Wall-mount design saves valuable space and allows for additional storage and flexibility. Highly efficient condensing Ultra-Low Nox tankless water heater delivers up to .91 Uniform Energy Factor (UEF). Safety features include exhaust & water temperature safety control, overheat cut-off fuse and air-fuel ratio (AFR) sensor. Wall-mount design saves valuable space and allows for additional storage and flexibility. Industry leading “Peace of Mind” 15-year limited warranty covers scale-related failures. The 140H Series offers high efficiency Ultra-Low NOx condensing technology allowing for the use of 3” PVC venting and has 0” clearance to combustibles. Indoor models are certified up to 10,100 ft. altitude. Provides a variety of installation options: indoor, outdoor and direct vent. Complies with Ultra-Low NOx regulations and meets the energy efficiency requirements of ASHRAE 90.1b-1992. The ATI-140H-N tankless water heater uses up to 120,000 BTUs of natural gas to deliver a max flow rate of 6.6 GPM. It utilizes condensing technology to achieve a Uniform Energy Factor of 0.90. this model meets Ultra-Low NOx emission requirements, and comes with a 15-year limited warranty. A. O. Smith’s ProLine water heaters are residential products built to commercial-grade standards and are only available for purchase through professional wholesalers and contractors.