My Furnace Is Leaking Into Vents

Problems Caused by Leaks

• A furnace that is leaking into your vents can cause several serious problems. First, the presence of so much moisture can be very inviting to molds. Once a mold starts to grow in your ductwork, it can spread spores around your house and soon begin cropping up in a variety of damp, dark areas. Second, if a furnace is leaking water into your vents, it might also be leaking exhaust, including dangerous gases like carbon monoxide.

Condensation

• Sometimes vent leaks are a direct result of condensation. The heated air holds a large amount of moisture and releases it as it exits the furnace. This causes the water found in the inside of vents. It is not a direct problem with the furnace but is connected to the humidity of the air. You can install another drain line or remodel your ductwork entry point to fix this problem.

Condensate Line Issues

• Many modern gas furnaces also have what is called a condensate line. These furnaces not only take heat from exhaust air, but they also take moisture at the same time. The condensate line drains the moisture out of the furnace. If the condensate line is cracked or blocked, then the water will leak into others such as your ductwork.

New Fittings and Repairs

• If water is leaking only out of your supply vent, you might not need to repair the furnace, since the supply vent does not connect with any indoor air system. However, if you notice cracks in your condensate line or venting system near the ductwork itself, it is time to find new fittings (most pipes that furnaces use are plastic) to stop the leaks. You might also need to replace the drain pan or unclog a drain to fix the problem.