What is the difference between a natural draft and a power vented system?

Natural draft systems rely on buoyancy to facilitate the movement of combustion gases through the venting system. This buoyancy is created by the temperature difference between the hot gases produced during combustion and the cooler air outside the vent. When air heats up, it becomes less dense and rises, drawing in cooler air to replace it and allowing the exhaust gases to exit the system efficiently.

On the other hand, power vented systems utilize a mechanically driven fan to forcibly expel combustion gases through the venting system. This active mechanism can offer greater control over the venting process, enabling the system to work effectively even in situations where natural draft would be insufficient, such as in locations where the outlet might be distant from the appliance or where environmental conditions inhibit natural buoyancy.

The emphasis in this context is on how these two methods of venting differ fundamentally in their operation: one relies on natural forces (buoyancy), whereas the other employs mechanical means (a fan). They can also differ in efficiency and application, but the primary distinction lies in the means by which exhaust gases are expelled.