More Info to start with. We're going to supply you with some necessary tips to maintain your ducts in optimal condition, such as normal inspections, the use of air purifiers, regular filter replacement, and proper HVAC system use.Inspect the ductwork visually to identify any signs of mildew, extreme dust buildup, or other issues which will demand supplemental focus.The flame sensor detects the existence of the flame and shuts off the gas valve When the flame goes out. The flue is actually a pipe that over at this website carries the combustion gases and steam from your combustion chamber to the surface.