Keep in mind that dampers are different from HVAC vents that open and close. When you close an HVAC vent, the air is still flowing along the duct. Meanwhile, dampers are positioned near the opening of a duct. Closing one will keep your HVAC system from even running cold or hot air through that duct.
Instead, a damper is located closer to your central HVAC unit, so unlike a vent, which only controls the flow of air in one room, closing a damper forces your system to redirect air somewhere else in your house. If you live in an older home, dampers may or may not already be a part of your HVAC system.
Shutting a damper ( or even a door in a room with no return) throws the dynamics off and can increase static and alter the airflow. This is a problem with poorly designed zone systems that have dampers that do close- If you are not spot on in a design, it will never be correct.
Closing the vents doesn't do it any favors. In fact, instead of helping the air conditioner cool less, closed registers force the same amount of air through other ducts. This builds pressure in the system and makes your HVAC system work harder to distribute the air where you need it.
By not creating an airtight seal, these dampers minimize the strain on the system. In summer, you can close the dampers downstairs so cooler air reaches upstairs rooms. But in winter, closing upstairs vents halfway allows heat to rise.
In the summer, the lower level is naturally cooler, and most people report having hot rooms. In the summer, it's critical to open the dampers on the upper level and block as much air from entering the basement as possible.
Static pressure in your air vents
Static pressure is the resistance to airflow in your HVAC system. These systems are designed to have the right balance of static pressure. Closing vents will increase the pressure, which can restrict or stop efficient airflow in your home.
Shutting Heating Vents in the Summer to Conserve Energy
That being said, it isn't something you should do for more than two or three days at a time. Leaving vents closed for extended periods can cause damage and expensive leaks.
Early System Damage
Closing off too many air vents in your home will restrict airflow. Restricted airflow causes many issues on its own and can lead to coils freezing and damage to the compressor.
Closing Air Vents: Why It's a Bad Idea in Winter
Making your heating system work harder to bring the temperature up in all rooms of the house. Further, reducing airflow to one room increases air pressure directed elsewhere throughout the duct system.
EXPERT RECOMMENDATION: If you want to try to balance the airflow throughout your home, you should not close vents completely; HOWEVER, you can close them slightly (not more than 75% closed) to help distribute air better to the areas that need it most.
A motorized damper regulates the flow of air inside your HVAC system, which in turn controls the temperature in your home. If your damper isn't working, you'll need to replace the part. Expect to pay an average of $350 to replace a motorized HVAC damper, with a typical range of $250 to $450.
Not all homes have dampers. If you have a premium HVAC system with “zoned heating and cooling,” your dampers are automatically controlled by your unit. (Score!) If you don't have a premium system, that doesn't necessarily mean you have them, though.
Because heat rises, homeowners can consider partially closing upstairs vents and fully opening those downstairs. The top floor often steals most of the heat, but partially closing vents can help to keep other areas of your house warmer without damaging or stressing your house's HVAC system.
By closing vents, you're not allowing your system to work less but instead increasing the pressure in your air ducts. Increased pressure in your air ducts is bad news because your blower is only designed to deliver a certain amount of air against a certain amount of pressure.
If the refrigerant is leaking, ice can start to coat various parts of your unit, leading to a complete freeze—especially when excess condensation is present. Signs of low refrigerant levels include a hissing sound coming from your unit, a lack of cool air in your home, and, of course, ice forming on your AC.
Add dampers to the ducts. This directs the airflow coming from the HVAC unit and shifts the desired amount to each room. Some ducts are already equipped with dampers and can simply be adjusted. Modify the settings of the air cleaner/filtration unit.
Although closing off unused rooms may seem like a way to save energy on heating and cooling, it can actually force your HVAC system to work harder. In order for your air conditioner to work efficiently, you should keep the interior doors in your home open as much as possible.
In most homes, dampers going to the upstairs are open in the summer and closed in the winter. By closing the dampers to the upstairs in the winter, it allows for the heat to rise naturally after first being introduced into the lower levels of the home.
Open vents may be less problematic in cold and dry climates, like those found in the northern United States. However, they can still contribute to heat loss and increase the risk of frozen pipes during winter months. Homeowners in these regions should consider closing vents during the coldest parts of the year.
First, heat rises, so it's normal for the second floor of a home to get hotter than the main floor.
Return air vents connect to your return ducts, and they're typically larger than supply vents. Again, depending on the design of your ductwork and home, HVAC return vent locations vary but are often in central areas, kitchens, bathrooms, and pollutant-prone areas so as to best collect stale or dirty air.