In which type of venting system is the removal of gases under nonpositive static pressure accomplished inside the appliance?

Induced-draft venting systems are designed to maintain the removal of combustion gases from appliances under conditions of nonpositive static pressure. This means that the system relies primarily on a fan or blower that operates to create a draft by inducing the flow of gases, propelling them through the venting system to the outside atmosphere.

In this type of venting, the appliance itself is aided by the induced draft to ensure that harmful gases, like carbon monoxide, are effectively evacuated, thus enhancing safety and efficiency. The mechanism allows for proper venting even when there may not be adequate natural draft, which can occur under certain atmospheric conditions or with specific installations.

The induced-draft venting system contrasts with other systems like power venting, forced-draft, or mechanical draft systems, each employing different methods or operating principles for gas removal. For example, power venting systems use a fan to create a positive pressure that pushes gases out, while forced-draft systems inject air into the combustion process to enhance combustion efficiency. Understanding the specifics of the induced-draft system is essential for ensuring adequate venting in various heating scenarios.