Over the years, homes have been built tighter and tighter to help save energy and keep the home warm. More efficient windows and doors, as well as air sealing in newer homes, have reduced random sources of air infiltration to almost nothing. The result is that it is harder for our homes to “breathe.” The more we do to help your home breathe, the healthier the air is for you to breathe.
If you have gas-burning appliances in your home, such as a furnace, water heater, fireplace, stove/oven, or clothes dryer, they need oxygen to combust. That oxygen has to come from somewhere, and it has to be continuously replaced. Some people think that it doesn’t make sense to have a vent that brings cold air into their home in the dead of winter, but it actually helps because it creates a safer and healthier indoor environment.
How Do Fresh Air Vents Work?
When explaining fresh air vents to my home inspection clients, I use the example of when I was young and growing up in a 1950’s vintage rambler home. When the furnace kicked on in the utility room, you could feel the cold air scooting along the floor from under the front door in the living room over to the air return across the room. You see, back then, we sat on the hard wood floor to watch the old black and white TV.
Fresh air vents help our homes and gas appliances breathe easier by bringing the air into the home where it is needed most. Typically, a fresh air vent will be located in the utility or mechanical room where you may have a furnace, water heater, and possibly a gas dryer. Fresh air vents provide the air needed for proper combustion and prevent backdrafting and carbon monoxide buildup.
Backdrafting
Let’s say, for example, that someone is cooking and running the exhaust vent in the kitchen, the exhaust vents in two of the three bathrooms are being used, and the clothes dryer is running. All of these are drawing air from within your home and venting it to the outside. Now the old water heater kicks on. If the old water heater has a standard atmospheric vent, the exhaust naturally rises up and out of the vent through the roof. Backdrafting is when the exhaust from a combustible appliance, like a water heater, is drawn back into your home instead of naturally drafting out of the roof vent.
Why Fresh Air Vents Are Important
Without a source of fresh air through a fresh air vent intake, your gas appliances will use the oxygen in your home as fuel. This may also lead to an unhealthy buildup of carbon monoxide. A fresh air vent will provide the combustion air needed for your appliances to run properly.
Identifying a Fresh Air Vent
During the course of a home inspection, our home inspectors confirm that there is a fresh air vent. The fresh air vent is typically found in the utility room next to the furnace and water heater. Many times, the utility room will also have a clothes dryer and a washing machine.
A Fresh Air Vent in a Utility Room
The fresh air vent will be a 6-to-8-inch duct that extends down to the floor, typically with a loop at the bottom, like the letter “J.” This duct may extend up through the home and into the attic or to a wall vent. Extending the vent to the attic prevents the force of wind from directly blowing into the vent.
A Fresh Air Vent in an Attic
What About the Cold Air?
Occasionally, during a home inspection, we will find rags, towels, or foam balls stuck in these fresh air vents in the utility room. Homeowners who do not understand the purpose of these fresh air vents think they are doing the right thing by blocking the cold air they feel coming into the room during the winter. Our home inspectors will explain the reasons for the vent and why the cold air is important.
Summary
It is important to have clean air in your home to breathe. The good, clean air coming from the outside while the dirty air goes out is a good thing. You can thank your fresh air vent for that. Remember, don’t block that vent, and make sure it is clear to draw air into your home.
At HomePro Inspections, our home inspectors are trained to inspect your HVAC systems and identify any defects. Any issues are documented in your home inspection report and recommended for resolution by a qualified professional.
Visit our website to learn more or to schedule your home inspection in the Rochester, Owatonna, and Faribault, MN areas. You can contact us today at (507) 202-8942 or utilize our online “Schedule Now” feature to set up an appointment.