Thread: Positive Pressure! Don't Breathe Stale Air - Add a Fresh Air Duct in your Home

I don't think this one is going to save much money, if any, but it's a good idea anyway. So here's what happens:

Your home is built air tight. Or so you think. Now you turn on your bathroom exhaust fan for 10 minutes and blow a few hundred cubic feet of air out of the house. Then you turn on your kitchen down draft and blow another 1000 feet of air out. Then some hot air rises through the crack where your attic door comes down and escapes into the attic. So what is happening in your house??? It's like sucking the air out of a balloon. The air pressure in your house becomes lower than the air pressure outside. This is called negative pressure. So for most houses, even the "air tight" ones, you will pull in outside air through little cracks around doors, windows or even baseboards to offset the negative pressure. This is unconditioned air that is either too hot, too cold, too humid or too dry. Maybe the really really air tight houses can combat this slightly, although having a totally air tight house is unhealthy for other reasons.

So now you have outside air coming in from various spots. In the summer it is hot and humid and in the winter it is cold and dry. Not good for trying to keep your house comfortable.

Here's the solution. Add a small duct to your existing HVAC unit to pull in a very small amount of fresh air. This air is immediately run through your HVAC unit, conditioning the air, but creating positive pressure in the house. Now instead of pulling air in through the cracks, you are pushing air out through the cracks, if anything. You might be thinking it's the same either way, but creating positive pressure has some advantages that I'll list below:



1. Positive pressure brings in fresh air that is immediately conditioned by your HVAC system.
2. You know that you are always exchanging some air in the house. Homes that are built too tightly can get stale air that is unhealthy to breathe.
3. You can help avoid radon in the basement. Radon builds up because the pressure of the soil around the basement is higher than the pressure in the basement. The radon actually seeps into your basement from the soil through your basement walls. Creating just a bit of positive pressure has proven to eliminate radon in most cases.
4. You can control how much fresh air you bring in. Look at something like www.aircycler.com that will control how often your HVAC fan will come on throughout the day and how often the fresh air duct will be open during that time.

Another option if you live in a very humid climate is to add a fresh air duct in conjunction with a dehumidifier. This ensures that the air you bring in isn't too humid and keeps the whole house more comfortable. This costs money to operate, but may allow you to keep the temperature a few degrees higher and still stay comfortable which can save you money overall..

Does your house have a fresh air duct? If so, how did you set it up and how is it working?