A. O. Smith Tankless Water Heater Gas – Propane – Outdoor – 6.6 GPM On Demand Hot Water – Outdoor – 120,000 BTU Condensing – ProLine® XE ATO-140H

Price: $899.99
(as of Feb 13, 2026 03:15:45 UTC – Details)

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 ATO-140H-P tankless water heater uses up to 120,000 BTUs of propane to deliver a max flow rate of 6.6 GPM. It utilizes condensing technology to achieve a Uniform Energy Factor of 0.91. 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.
ProLine XE Ultra-Low NOx Outdoor 120,000 BTU Condensing Propane Tankless Water Heater Outdoor Propane 140H. Continuous hot water flow rate up to 6.6 GPM.
Wall-mount design saves valuable space and allows for additional storage and flexibility. Vents with 3” PVC up to 70 feet or 4″ PVC up to 100 feet.
Safety features include exhaust & water temperature safety control, overheat cut-off fuse and air-fuel ratio (AFR) sensor. 15-year limited warranty on heat exchanger in residential applications.
Primary commercial-grade copper heat exchanger is 25x better than stainless steel at heat transfer, stabilizing outgoing water temperatures quicker.
Secondary heat exchanger is made of 316L Stainless Steel to protect against corrosion.