Do you close air vents in unused rooms to lower utility bills?
Well—surprise—doing so may actually raise your utility bills—and make you less comfortable at home.
How in the world could closing air vents do all that?
Basically, closing air vents does not make your AC or furnace run less. It just forces the same amount of air through less exits.
This increases pressure in you air duct system. Extra pressure forces more air out of leaks in your duct system.
Oh, right. Air duct leaks. Most homes have them.
The average home loses about 20-30% of the air passing through the air duct system, because of leaks, holes, and poorly connected ducts, according to ENERGY STAR.
Since your system isn’t delivering all the conditioned air to your rooms, it must run longer to reach your thermostat temperature setting.
So, there you go. Closing air vents can lead to higher utility bills.
If closing air vents forces more air out of supply side air duct leaks, then that means less conditioned air is being delivered to certain rooms in your home.
For example, during winter you may notice a room that’s hard to heat because there’s very little air coming out the supply air vents. That could be partially due to air duct leaks.
The reduced airflow may also be due to the blower slowing down because it can’t work against the extra pressure caused by the closed air ducts.
Remember, your HVAC system is designed to heat and cool all your living spaces. It does not understand that you’re not actually living in some of them.
Closing vents will only:
Minneapolis Saint Paul Plumbing, Heating and Air has served the Twin Cities since 1918.