Why Does Metal Chamber Pipe Get Condensation in It?

Natural Condensation

• For the same reason that a cool glass attracts moisture in a warm room, ductwork and other metal surfaces around a furnace or air conditioner can create condensation. Warm air easily holds water vapor. When warm air is cooled, it loses its moisture through condensation, leading to water droplets forming on nearby surfaces. This is seen in air conditioners as the conditioner cools the air in its ductwork. It is also seen in furnaces when heated air cools while circulating throughout the house.

Water Sources From Fuels

• Another reason condensation forms in metal chambers is connected with fuels. This applies only to furnaces and other heating units. When these units go through a cycle, they burn fuel, such as oil or natural gas. Some fuels, notably natural gas, contain water vapor. This water is released when the fuel burns, so furnace exhaust causes water to collect more easily on the furnace’s pipes and chambers.

Condensation Drainage

• Modern natural gas furnaces are efficient. Many contain a secondary component that runs through the exhaust and draws heat from it for reuse. This process produces extra condensation as the exhaust cools, which is why you may notice more moisture in newer furnaces. The furnace contains a drain pan that collects this moisture and funnels it down to a drainpipe, so that it does not collect in the furnace.

Leaks

• If you notice extra moisture in your furnace where it has not been before, this could be a sign of a leak. You may have a cracked heat exchanger, a serious problem that requires replacement. Your drain pan or drain line may have also become clogged, less serious issues you can fix with a thorough inspection and cleaning.