Ensure your furnace is properly vented.

HealthyHouseTM CleanAir Tip

 High-efficency furnace design. Air from outside pulled into combustion chamber and exhausted back outside.

High-efficency furnace design. Air from outside pulled into combustion chamber and exhausted back outside.

The majority of modern-day furnaces and condensing boilers are designed to use outdoor air in the combustion process. This is a crucial step to get right in the installation process, yet some HVAC contractors repeatedly install these units incorrectly. Some inspectors also routinely overlook these incorrect installations.

High-efficiency furnaces have two venting ports: an intake and an exhaust. The intake port, also referred to as the fresh-air intake, should be connected via piping to the outside. The exhaust port should also be piped to the outside via a separate pipe. This allows outdoor air to be pulled through the intake pipe, into the combustion chamber, and vented back out of the house via the exhaust pipe.

 Intake pipe shown is not connected to outside. In this installation it is pulling in indoor air instead of outdoor air. PVC pipe should have been run to outside the house. Sometimes no PVC at all is connected to the intake port.

Intake pipe shown is not connected to outside. In this installation it is pulling in indoor air instead of outdoor air. PVC pipe should have been run to outside the house. Sometimes no PVC at all is connected to the intake port.

The mistake commonly made is that the intake port is not piped to the outside of the building. When this is done, indoor air is pulled into the combustion chamber and the house is put under negative pressure. This creates a pressure imbalance since the furnace exhaust fan is taking conditioned indoor air and shooting it right out of your house. This causes make-up air to be sucked from places you don’t want it to be, such as wall cavities, sump basins, unconditioned attics and crawlspaces. This can lead to a multitude of indoor air quality problems. Dust particulate can be pulled into the living spaces including things like mold spores and fiberglass. Decomposition gasses can be pulled from drains and sump basins. Radon can also increase when this mistake is made.

Not only does this mistake decrease the healthfulness of your home, it decreases the efficiency of your furnace. Examine your high-efficiency furnace or boiler to ensure it has intake and exhaust pipes properly vented to the outside.

 Intake and exhaust vents terminated on side of house.

Intake and exhaust vents terminated on side of house.

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