What does a condensing boiler do with exhaust gas?

A condensing boiler is designed to maximize energy efficiency by extracting heat from the exhaust gases produced during combustion. This process involves taking the hot gases that would typically be expelled into the atmosphere and utilizing their heat to preheat the water returning to the boiler. As the exhaust gases cool, the water vapor present in the gases condenses into liquid form, releasing additional latent heat that can be harnessed.

This ability to extract heat until the water condenses is what sets condensing boilers apart from traditional boilers, which do not recover this additional heat. By utilizing both sensible heat and latent heat, condensing boilers can achieve higher efficiency ratings and lower greenhouse gas emissions, contributing to more environmentally friendly operation in heating systems.