Is Closing Vents Bad for HVAC?

Closing vents in your home may seem like an easy way to save money on heating and cooling, but it can actually have adverse effects on your HVAC system. To understand why we need to look at how HVAC systems work and the mechanics of venting in more detail. 

Closing vents can prove hazardous to your HVAC system. When HVAC systems are not adequately ventilated, they may become damaged or break down entirely, which can cause significant problems with your indoor air quality. Long-term effects such as pressure buildup and leaks can leave permanent damage. 

One of the biggest misconceptions about HVAC systems has to do with closing vents in various rooms of your home. Although many people might assume this can save them money on heating and cooling costs, the reality is that you’re putting an extra burden on your HVAC system. The remainder of this article will discuss why closing vents is harmful to HVAC.

Why You Should Never Close Your Vents?

One of the main reasons why people should never close their vents is that airflow restrictions can lead to a breakdown. This might not seem like an issue at first glance, but it will cost you more money over time on air conditioning bills if you start closing your vents. Plus, if anything gets trapped inside of the ducts and clogs them up, it can damage the fan or make one of your motors stop working altogether. 

By closing your vents, you also leave your blower running at full capacity, which can lead to all sorts of damage or discomfort. Pressure buildup will damage the blower, and there will be no way to remove heat inside your home on hot days.

Closing vents have a range of adverse effects. For example, when too many air returns are closed, the air supply may run out, and the cooling units won’t be able to turn on, which will lead to overheating. And when leaks happen without circulation, they’ll go undetected until they get worse and more expensive to fix

Closing vents can also slow the evaporation process of your cooling unit’s coil, reducing its lifespan and resulting in higher energy bills. All of these problems have long-term effects that could make an already pricey job much more expensive with costly consequences. The solution is simple: don’t close vents!

Read: How To Fix Ecobee Thermostat AC Blowing Cold Air Through Intake Vent?

What Do HVAC Experts Say About Closing Vents?

HVAC experts DO NOT recommend ever shutting your vents or registers completely. When you close vents, you deprive your home of an essential source of fresh air, which can mean a buildup of unpleasant odors and moisture. This moisture accumulates when the home’s airflow is disrupted by closed registers. 

For optimal energy efficiency and indoor air quality, it’s best to keep your air registers or vents open at all times. However, if your local region has a strict building code requirement, then it’s essential to close off unoccupied rooms’ registers during the cooler seasons or whenever they’re not in use.

Read: Why Dust Coming Out Of Air Vents?

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Five More Reasons Why You Should Avoid Closing Vents

  • Poor efficiency. One reason to never close your vents is that it can reduce the efficiency of your heating and cooling system. Your AC needs cold air to operate correctly. When all the vents are closed, all the air is recirculated, and your AC has to work harder. 
  • Mold growth. Closing vents significantly reduce indoor air quality. Reduced airflow increases the risk of mold growth, as mold needs oxygen and moisture to grow. In addition, closing vents will increase energy consumption costs and shorten equipment life because ACs need to run longer than they usually would.
  • Carbon monoxide. Carbon monoxide is a deadly gas. If you notice a strange or strong odor in your home, it may indicate that there’s excess CO gas inside of it. You should never ignore these odors or other signs that indicate CO poisoning because they can seriously harm your health and even lead to death if they aren’t addressed. The best way to reduce carbon monoxide is to open vents. 
  • Discomfort. If you live in a warmer climate, this may not be as much of an issue, but during the winter months, when it is colder, and your heater needs to work extra hard to maintain comfortable temperatures, closing vents can lead to drafts and other uncomfortable conditions.
  • Temperature humidity imbalance. Air flowing through the ducts is key to cooling your home correctly and circulating air which removes dust and particles from the AC. When closed, you essentially create a heat pocket which makes it harder for air to move around your home effectively. You may also see an increase in dust buildup on coils, leading to a temperature humidity imbalance.

What To Do Instead of Closing Vents?

Partially Closing HVAC Vents

As much as we all want to be energy efficient, sometimes closing vents in unused rooms is not the best way to go about it. Partially closing vents can actually do more to improve your home’s energy efficiency. By only closing the vents by about half, you can still maintain airflow throughout your home while reducing the energy your HVAC system uses. This is a great way to save money on your energy bill and help the environment simultaneously!

Read: Why Are HVAC Vents Under Windows?

Managing Air Flow Efficiently

One way to improve the efficiency of your home’s heating and cooling system is to manage airflow efficiently. This can be done by sealing off unused rooms and ensuring that all vents are fully open. You may also want to consider installing a zone control system, which can help you to better manage the temperature in different areas of your home. By taking these steps, you can help ensure that your home is as comfortable as possible while saving money on your energy bills.

Checking for Leaks

Closing off vents does not have any savings benefits for your system–you’re better off seeking out the source of the air leak rather than shutting down ducts. 

There are four common causes of leakage: 

  • Condensation (particularly problematic during humid months).
  • Gaps or cracks around pipes or wires.
  • Unsealed windows and doors.
  • Improper installation or lose joints with ducts.

Add Weatherstripping

Weatherstripping can be applied at points of leaks to prevent air from escaping. This prevents your home from losing heat and coolness in winter and summer. This can be done without breaking the bank because some solutions are as easy as buying weatherstripping tape or door sweeps. Some other materials that are used include foam sealant and self-adhesive draft blocker strips.

Read: How To Keep House Ventilated In Winter? (10 Tips)

Call an HVAC Professional

If you’re having trouble with your home heating and cooling system, it’s essential to call a professional rather than simply closing vents. By doing this, you could actually make the problem worse. A professional can help troubleshoot the issue and come up with a resolution. 

There could be a number of reasons why your home may not be comfortable, even with the vents closed. It could be that your HVAC system is too old and needs to be replaced. Or there could be a problem with your ductwork. Either way, it’s best to call a professional to take a look. Trying to fix the problem yourself could end up costing you more in the long run.

Read: Do I Need Filters In My Return Vents?


So, is closing vents bad for HVAC? Yes, it is. Closing vents increases the energy consumption of your HVAC system, and it can cause your system to overheat. Additionally, closing vents can lead to uneven temperatures in your home, and it can put stress on your HVAC system. If you’re having trouble with your HVAC system, talk to a professional before closing any vents.