How to Check for Air Flow Problems in Attic Ducts

Examine the air filter to ensure it isn’t clogged. Sometimes something as simple as a clogged filter can cause air flow problems. If the filter appears dirty, replace it and check whether that solves the problem. If the filter is missing, it may have fallen into the ducting, so check to make sure it isn’t blocking the blower intake.

Inspect the attic ducts to make sure they are in good condition. Sometimes ducts can become separated, usually at the seams where the sections of ducts are joined. Look for signs of splits, cracks or gaps along the seams. These can allow the air to leak out, resulting in serious air flow problems.

Remove grills from the duct outlets, and use a flashlight to look inside for signs of blockages. Note that the grills may be held in place with two to four screws in the ceiling, floor or wall. A buildup of matter in the attic ducts is likely if there are leaks in the system, but can also occur from debris that has accumulated in the ducts through the blower. Dirt, insulation or other materials can block the free flow of air throughout the house.

Check the air flow ducts to see whether they were installed correctly. The main duct coming from the blower should be the largest, and each time it splits, the ducts that branch off should be smaller than the one they are coming from. This allows the air pressure to stay steady as the air is diverted throughout the house. If the ducts in the attic branch off in different directions but are all the same size, the pressure furthest from the blower will be inadequate. If this is the case, the ductwork needs to be redone.