mobile navigation
close buttonClose Menu
close buttonClose Menu
pacific heating cooling


(253) 292-3995
close buttonClose Menu


Why You Shouldn’t Block HVAC Air Vents and Registers

by vscontent on November 15, 2015

closing off HVAC vents and registers

Consequences of Closing Off Air Vents and Registers

While it may seem logical to close off air vents and registers in unused rooms to save energy, it could in fact lead to blower motor problems, mold growth, decreased airflow, duct leakage, refrigerant leaks, cracks in your heat exchanger, and a blown or frozen compressor.

When air vents are closed or unintentionally blocked, your HVAC system doesn’t know this and so continues to pump out the same amount of conditioned air as always. Each HVAC system is specifically designed for a certain amount of square footage. Closing vents and registers will only cause insufficient airflow and increased pressure. As a result, various components on your air conditioner could freeze and fail early and your heat pump and heat exchanger could develop problems as well.

The more vents and registers you close or block, the higher the pressure inside your duct system. The high air pressure combined with low airflow also creates temperature problems with your heat exchanger, which could develop cracks. A cracked heat exchanger is the number one cause of furnace carbon monoxide leaks.

If you live in a humid climate, closing off vents could create a breeding ground for mold and mildew. Even in dry climates, this could become an issue.

If you’re blocking the air registers in your home to divert cool or warm air elsewhere, chances are that you’ll end up having to replace your HVAC system sooner than you’d like to. Or, you’ll develop leaks in your duct system, leading to serious energy losses and airflow problems. This leaves a lot of customers upset.

Even if you haven’t manually closed off or blocked your vents, you could be unintentionally blocking them with drapes, rugs, or furniture. It’s a good idea to go around your home looking for blocked vents and registers. Check behind furniture, drapes, rugs, and other object that may be obstructing airflow from your supply or return grills.

If you’re not feeling comfortable in your home, there are still a few things you can do to try and counteract the problem at hand. Instead of blocking the air registers, consider these options:

  • If one room is cooler or warmer than another, adjust the damper some to make both rooms comfortable. To ensure proper airflow, have a licensed, professional technician check the static pressure.
  • Call in a professional to conduct a home heating and cooling assessment to locate the cause of uneven temperatures.
  • A dirty air filter also creates higher pressure and low airflow for your HVAC system, so remember to check and/or change your filter every 30 days.
  • Have a fan run constantly to compensate for the unevenness of temperatures between rooms and to help distribute the conditioned air. In the winter, you can switch the direction of your fan blades to push the warm air near the ceiling down to the living areas. This updraft is created by flipping the small black switch located on the base of your ceiling fan.
  • Have you considered a zoning system? These ductless mini-split systems call for multiple thermostats in your home, and each system can be run separately. This way, you are only heating and cooling the rooms in your home that you are currently using, saving on energy costs.

For a more thorough explanation as to why it is NOT a good idea to close vents and registers in unused rooms, read this article by

Heating season is upon us. Call the experts at Pacific Air Systems to restore comfort and balance back to your home with our precision heating tune-up.

For more useful home cooling information, keep in touch with us on Facebook, Twitter, LinkedIn and Google+!