“Closing vents in rooms we don’t use will save me money.”
Many Arizona homeowners think this, but it’s 100% wrong. It’s even worse than wrong; closing vents can actually cause your AC or heat pump to run inefficiently and eventually break.
We’ll explain why:
If you close air vents, your air conditioning and heating system will not run less and therefore you won’t save money as hoped.
Imagine that you’re walking at a brisk pace, and you’re breathing by inhaling through your mouth and exhaling through your nose. Moving air like this is how your HVAC (heating, ventilation and air conditioning) system works; the blower pulls air from the house through the return ducts and then pushes it back into the house through the supply ducts.
Now, imagine you decided to close one of your nostrils, but you continue to walk at the same pace. By doing this, you’re trying to move the same amount of air but have less pathways to do so. So, you either move less air (making you oxygen deprived), or you put in more effort to breathe comfortably.
Similarly, when you close a supply vent, you’re not causing your air conditioner to work less. All you do is increase pressure in your air ducts. Which is bad news for the blower because it’s designed to deliver a certain amount of air against a certain amount of pressure.
Closing vents will cause different problems depending on the type of blower:
OK, so now you know what happens when you close air vents. But how does that actually hurt the system?
Well, since a PSC blower (the most common type) slows down when you close vents, less air is delivered over your:
And if you don’t have a warranty that covers these parts? You might as well replace the entire outside unit or furnace respectively because it would be more cost efficient than replacing those pricy parts.
So, we’ve covered the most important problem with closing vents: a damaged system. But there are a few other important problems closing vents can cause, including:
Remember, a PSC blower delivers less air, the more vents you close. That means your home will take longer to cool down or heat up.
Increased duct leakage
The average home loses 20-30% of the air blowing through it thanks to air duct leaks, according to ENERGY STAR. That means you’re paying 20% to 30% more than you should on your utility bills.
Closing vents worsens that leakage problem because the extra pressure forces MORE air out of those leaks. Think of it like jumping on top of a leaky air mattress. The mattress was already losing air, jumping on it just forces more air out of the leaks—and possibly making the leaks open even more.
Of course keeping vents open does not make the duct leakage problem go away. You would need a professional to seal the ductwork.
Learn more: How Can I Tell If My Air Ducts Are Leaking?
Now, we don’t mean to be fear mongers here. Closing one vent isn’t going to instantly just ruin your system. But, we are saying that with every air vent you close, the above problems are more likely to happen. That’s all.
Have any other questions about the do’s and don’ts of cooling and heating your home?
If you live in the Phoenix metro area, contact us with your questions. We would love to help!