Over the last 20 years, a new generation of higher-efficiency gas furnaces and boilers has come to market. An essential difference in the design of these units is how they are vented, eliminating the need for dilution air. The combustion of natural gas produces certain by-products, including water vapour and carbon dioxide. In a conventional gas furnace, such by-products are vented through a chimney, but a considerable amount of heat (both in the combustion products and in heated room air) also escapes through the chimney at the same time. Heat is also lost up the chimney when the furnace is off.
The newer designs have been modified to increase energy efficiency by reducing the amount of heated air that escapes during both the on and off cycles, and by extracting more of the heat contained in the combustion by-products before they are vented.
Types of Boilers
- Non-Condensing Gas Boilers
- Condensing Gas Boilers