What type of venting system is necessary for high-efficiency furnaces?

High-efficiency furnaces are designed to maximize thermal efficiency, often achieving efficiencies of 90% or higher. One of the key characteristics of these furnaces is that they extract additional heat from the exhaust gases by utilizing a secondary heat exchanger, which significantly reduces the temperature of the flue gas.

As a result, the venting system for high-efficiency furnaces must be able to accommodate these cooler exhaust temperatures. PVC venting is commonly used because it is resistant to corrosive condensate produced during combustion, and it can handle the lower temperatures of exhaust gases without any risk of damage. PVC is lightweight, easy to install, and provides effective sealing due to its compatibility with the furnace's venting requirements.

In contrast, metal ducting is typically intended for higher-temperature applications and may not be appropriate for the corrosive conditions present with high-efficiency furnaces. Chimney venting, while suitable for traditional furnaces, does not accommodate the unique requirements of high-efficiency systems. Double insulated venting could be considered for different applications but does not specifically cater to the needs of high-efficiency furnaces as effectively as PVC venting does. Therefore, PVC venting is the preferred and necessary choice for properly venting high-efficiency furnaces