Gas Fitter Test 2025 – 400 Free Practice Questions to Pass the Exam

When converting a furnace, it is necessary for the flue collar to be installed at a minimum height of 12 inches above the burner. This requirement is crucial for proper venting and to ensure that exhaust gases are safely and effectively expelled from the furnace. The height helps to prevent any backdraft that could lead to dangerous gases like carbon monoxide being trapped in the living space.

Proper clearance above the burner reduces the risk of interference with the combustion process, which can be adversely affected by improper venting heights. By maintaining this 12-inch distance, it ensures that the flue gases can rise freely and dissipate properly, thereby maintaining safe operation. The higher installation also accommodates variations in flue pipe configurations and local building codes, which often mandate such specifications for safety and efficiency.

Other height specifications, like those that are shorter, do not meet safety standards or may not allow for optimal venting, which is why they are not suitable choices for this requirement.