The flue is the vent that is used to expel exhaust gases from the combustion chamber. Handling the exhaust gases properly is very important because carbon monoxide is a byproduct of combustion. Checking for leaks is the first step. Look for any gaps or cracks. Small holes can be sealed with foil tape while corroded flues need to be replaced.
Next, check the damper on the flue. For oil-burning units, and some gas, the damper keeps the air moving to help gases up the flue. Too little flow and the gases won’t be properly vented. Too much flow and the hot air will be sucked out before transferring the heat in the heat exchanger.
Replacing the Oil Filter
The oil filter collects tiny pieces of debris from entering the burner. If impurities reach the burner and clog the nozzle, it could shut down the furnace. Close the oil valve and remove the old filter. Attach the new filter and reopen the valve. Make sure to dispose of the old filter in accordance of local regulations.