The Truth About Closing Vents: Why This HVAC Hack is a Total Bust

An air register vent in the wall partially closed.

You turn out the lights before leaving a room because your parents raised you right. You know that leaving lights on is wasteful. By that logic, shutting the vents would be similarly wise. After all, there’s no sense heating or cooling a vacant room.

But your HVAC system doesn’t operate in the same way that your electrical system does. While turning out the lights saves electricity, closing the vents does little good. In fact, this supposed HVAC hack will only raise your utility bill.

Why Your HVAC Needs to Distribute Air Evenly

Your heating and cooling system was designed to distribute a certain volume of air. An HVAC technician sized the unit based on several factors, including:

  • Your home’s square footage and layout
  • The amount of energy required to heat and cool the space, called British Thermal Unit (BTU)
  • The height of your ceilings is taken into the account

That’s just a basic calculation. A more advanced measurement also takes into account the number of people in your home, how many windows you have, and insulation, among other variables. Basically, your central heating and cooling system are fine-tuned to deliver the exact amount of air needed for your comfort -- nothing more, nothing less.

Closing the vents throws all of these careful calculations out the window.

Related: How Your Furnace is Drying Out Your Air

What Happens When You Close the Vents

A closed vent doesn’t reduce the volume of air your home requires to maintain a comfortable temperature. Your HVAC system will continue to produce the same volume regardless of how many vents are open.

As a result, pressure builds up within the system. The consequences aren’t pretty.

Restricted airflow can lead to a breakdown: A closed vent can create something of a back-up of air. This increases the strain on your heating and cooling system, which could result in a premature breakdown.

Closed vents could damage your ducts: Contrary to popular belief, closing the vents doesn’t redirect the air, at least not where you want it. All that air will find somewhere else to go, likely through leaks already present in your ducts. Forced air will make those leaks larger, sending as much as 30% of your cool or warm air to the attic or basement.

Blocking airflow creates a temperature imbalance: Heat flows from hot to cold. That means you’ll lose warm air to chilly spaces adjacent, and vice versa. This compromises your comfort and forces your furnace or AC to work harder to reach your desired temperature. The result: higher energy bills.

What You Can Do Instead of Closing Vents

There are better ways to cut your heating and cooling bills.

  • Stay on top of filter changes: Replacing your air filter every 30 to 90 days will allow air to flow unimpeded so your HVAC can operate more efficiently.
  • Schedule routine maintenance visits: Tune-ups in the spring and fall will prevent breakdowns, prolong the lifespan of your HVAC system and keep it running at peak efficiency.

Turn to the Fairfax heating and AC experts at Air Treatment Company by calling (703) 270-0881.

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