Is Closing HVAC Vents In Unused Rooms A Good Idea?

Did you know that you could be subjecting your HVAC system to a series of unintended consequences if you close vents in unused rooms? It turns out that you may not save money by closing vents – and you could be causing a world of problems.

As you probably realize, HVAC systems use a lot of energy, perhaps as much as half of all your home’s energy usage. That means you want to reduce your costs and save energy in every way possible. And many people are surprised when they learn that closing vents doesn’t necessarily lead to savings. While home HVAC vents usually have levers that allow for adjustment, they also allow the vents to be closed. But you may want to forget about the closed setting altogether.

Understanding Air Distribution

Your air conditioning and heating system’s blower pulls in air from inside your home through the system’s return air ducts. It then pushes the air back into the house through the supply ducts and vents. If you have a high-efficiency system, you have an ECM motor – or an electronically commutated motor. Most other systems have PSC or permanent split capacitor motors. ECM motors can vary air speed; PSC motors cannot.

Whichever is the case for you, the HVAC system is designed so that the blower pushes against a maximum pressure difference. When the filter is dirty or the supply ducts are restricted – as when ducts are closed – the blower must push against a higher pressure than it was designed. Neither kind of blower can perform properly under that condition.

When you further consider that most older home HVAC systems are far from ideal anyway, that makes the problem worse.

Why Closing Vents Is A Bad Idea

Closing vents increase system pressure, and that’s bad. It’s hard on the blower – and since most home duct systems aren’t sealed, it means more duct leakage. The more vents you close, the worse the problem gets. Take note that this issue impacts both heating and air conditioning, and closing vents is a bad idea no matter which system you have turned on.

When you close vents, you may create the following consequences:

  • Greater air duct leakage
  • Lower air flow if you have a PSC blower
  • Higher energy usage if you have an ECM blower
  • Comfort issues in your home because of restricted airflow
  • Freeze-up of your air conditioner coil
  • Dead compressor from the extra strain
  • Cracked heat exchanger and the potential for carbon monoxide leakage inside your home
  • Increase in particulate matter brought into the home because of unbalanced system issues
  • Condensation and related mold growth in rooms with closed vents where the HVAC dehumidification effects don’t work full
  • and more.

Of course, you may not experience all of these problems from just one or two closed vents, but why take the risk?

In the best case scenario, your HVAC system is carefully balanced to provide maximum heating and cooling throughout your home. Closing vents interfere with the way the system works.

In the worst case scenario, your system wasn’t designed very well in the first place or has perhaps been negatively impacted by age, dirt and neglect. It doesn’t perform with optimal efficiency anyway, and closing air vents could put enough stress on the system to cause it to fail.

If you’re experiencing problems keeping your home comfortable and are considering closing off unused rooms or making an adjustment to your HVAC system, don’t take action without consulting with our experts. There are ways to solve every heating and air conditioning problem correctly, and we can help you find them.

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