How They Work Condensing systems have a second heat exchanger and are designed to loop exhaust back through the system before releasing it. These gasses aren’t especially hot (usually around 100 degrees), but as they pass through the secondary exchanger, some of their heat is transferred to incoming cold water. The water then passes through […]

How They Work Non-condensing models are the more basic form of gas-powered tankless water heater. As such, they have only one heat exchanger. The exhaust gasses are a much higher temperature as they leave the unit and are vented directly instead of being looped back through the heater.