What Happens When You Close Air Vents? Facts vs Myths
Keeping your home at a comfortable temperature uses a lot of energy. That’s because heating and cooling usually comprise half of your total electricity use. Closing air vents in unused rooms may be one energy-saving tip you’re probably considering. If you haven’t started employing that strategy, we advise you not to do so.
Contrary to popular belief, closed air vents don’t promote energy efficiency. Instead, they do the exact opposite and may even create more harm than good. Here is some information about closed vents and their impact on your electricity bills.
Managing Air Flow Efficiently
We agree, providing heating or cooling to unoccupied rooms can be a waste of electricity. However, closing the vents to those areas is not the solution and can even detract from your purpose of conserving energy. Managing the airflow more efficiently would be the wiser move.
How do you do that? An excellent solution exists but before we go into that, let’s look at some pertinent questions regarding airflow.
Does Closing Vents Redirect Air?
The HVAC vents in your home allow hot or cold air to flow into the different rooms of the house. It’s a common belief that closing the vents in one area will redirect the conditioned air to other sites. Well, the air does get redirected but not where you specifically want it to go.
Closed vents push the air back into the ductwork, increasing the pressure within the ducts. The added stress can lead to leaks allowing the redirected air to escape to unconditioned spaces of your home. Closing supply vents also cause added pressure in the ductwork, causing more air to leak into areas that don’t need conditioned air.
Does Closing Vents Save Energy?
Closing the air vents won’t cause your HVAC system to run less. What it does is to force the air coming from the furnace through fewer exits. This raises the pressure inside your duct system. Now, almost all ducts have some leaks, leading to average energy losses of around 20-30% of the air that flows through the ductwork.
When the pressure increases, more air leaks out, forcing your furnace to work harder, which hikes up your energy bills.
Does Closing Vents in Unused Rooms Help Airflow?
No, it doesn’t. In fact, it does the opposite, and it poses additional risks, too.
Closing the vents decreases the return airflow, which can cause the heat exchanger to overheat, damaging this expensive component of your HVAC system. You don’t want to operate a defective heat exchanger because it can cause carbon monoxide to seep from your system.
Does Closing Vents Help Other Areas of the House?
It’s a myth that closing the vents helps other areas of your home get more conditioned air. Instead, the air you want to redirect into the rooms you use gets lost through the duct system. As a result, some areas in your house don’t get the cooling or heating they need.
Rather than increasing the comfort of your home, closing the vents detract from it and even raises your energy consumption.
Closed Vents Increase Pressure
Closing the vents raises the air pressure inside your duct system. Well-sealed ducts can lead to some increase in airflow in other rooms. However, the hot or cold air may take a circuitous route to get to its destination. This impacts the energy efficiency of heating and cooling systems and leads to higher power consumption.
If your home has leaky ducts, the extra pressure will simply push the heated or cooled air out through the leaks. As a result, less conditioned air gets to the rooms you want to heat or cool.
Should I Partially Close Vents?
If you want to save on energy, you can partially close air vents that are furthest away from your heating system. Because they still allow air to flow through your HVAC system, partially closed vents won’t cause a pressure build-up in the duct system.This lessens the risk of causing damage to the heat exchanger or compressor.
Should I Close Basement Vents?
A centralized heating and cooling system are designed to manage the temperature control of the whole house, including the basement. Thus, sealing the vents in that area will lead to the same issues caused by closing the vents in the upper sections of your home.
To prevent increased energy consumption and potentially damaging the HVAC system, keep the air vents open in all the areas of the house.
Closing Air Vents Damages Your HVAC System
If you close the air vents, your aim to save a few bucks on power costs can backfire and lead to more expenses. That’s due to the damages your HVAC may sustain. Let’s take a look at some of the possible effects closed vents have on HVAC systems.
System Damage
Closing the air vents restrict airflow, which can damage your heating, ventilation, and air conditioning. The exact issues it may encounter will depend on the type of blower it uses.
Permanent Split Capacitor (PSC) Blower
This type of blower only blows air at a fixed speed. It can’t go faster to overcome the pressure created by the closed vents. As a result, the evaporator coils in your air conditioning system can get too cold. This causes the liquid refrigerant to flow back into the compressor, potentially causing damage to the most expensive component of your system.
You’ll need to replace or repair the compressor before your HVAC system can function at peak efficiency once more. How much will a new compressor cost? Roughly around $1,200. That’s a huge chunk of money down the drain.
Inadequate airflow can also cause your heating system’s heat exchanger to overheat and crack. A new one costs around $1,500 on average.
Electronically Commutated Motor (ECM) Blower
Unlike the PSC blower, the ECM blower can adjust the motor’s speed according to the level of work needed. Closing the vents when your system has an ECM blower won’t eventually cause a breakdown. However, it will force the motor to work harder to compensate for the extra pressure, thus increasing your energy consumption.
Burst Ducts
Closed vents not only intensify duct leaks but may even cause the ducts to burst due to the pressure build-up. As a result, the air that should go into your living space gets diverted to areas that don’t need it, such as the attic or crawl spaces.
Having the ductwork replaced will set you back around $35 to $55 per linear foot, inclusive of labor and materials.
Lost Efficiency
If you selected your system based on efficiency, you risk losing that benefit if you close the vents. Remember how you factored in the size of your home when you purchased your unit? That means the components are primed to work together to efficiently cool a specified area.
You might think that you’re helping your air conditioner cool a smaller space when you close the vents, which will lower its energy consumption. However, that’s not the case. Closing the vents in other rooms forces the same amount of air through the other ducts, which builds pressure in your ductwork. As such, your heating and cooling system needs to work harder to get the air to areas of the home that need it.
Carbon Monoxide
Closing the air vents can cause the heat exchanger to overheat and crack. This can release carbon monoxide into your living space. This deadly gas is undetectable to humans. You won’t know you’re inhaling it until you pass out from lack of oxygen in your brain.
Mold Growth
Closing the air vents lowers the surface temperature in the unused rooms. Condensation occurs as a result, which can lead to mold and mildew growth. Molds and mildew can impact your health, especially if you suffer from allergies or asthma. They can also irritate your nose, eyes, skin, lungs, and throat.
Dangerous Long-Term Effects
Regularly closing the air vents poses risks to your HVAC system. The constant build-up of static pressure inside the ducts can lead to long-term damage to the compressor and heat exchanger of your cooling and heating units.
The Benefits of Balance
HVAC systems work best when air delivery is balanced. Sealing off a room leads to higher pressure in the area, which affects the interior climate. That’s because the room still has other access points, such as doors and windows, where air can come in.
Due to the pressure imbalance, unconditioned air can get in, creating hot and cold spots around the house.
The Only Way Closing Vents Could Work
Basically, closing the supply vents changes what comes out of the other sections of the house. However, it doesn’t change what the HVAC’s blower has to do to get heated or cooled air into those sections.
Instead of letting you save on energy, closed vents lead to increased power usage because the blower’s motor has to work harder to get the air where it needs to go. That’s on top of the air loss caused by leaky ducts.
Still, there’s a way wherein closing vents will deliver more conditioned air to rooms you use while helping you save on energy use. This is by investing in a system that works differently. In this system, closing a vent will signal the blower to move less air and your heating and cooling units to produce less hot or cold air.
FAQs
Do bedrooms need return air?
Yes, they do. The HVAC system blows air through the room, changing the air pressure inside. To maintain consistent pressure, the excess air has to go somewhere. That place is the return air vent.
Without an air vent, the HVAC system will have trouble keeping the room’s temperature at a comfortable level.
Is it better to have air vents on the floor or ceiling?
Regarding energy efficiency, air vents near the ceiling are the more effective options for delivering cool air than those installed on the floor. With floor vents, furniture can block the airflow, which leads to uneven air distribution throughout the room. In contrast, the air coming from ceiling vents can circulate freely because there are no obstructions to impede its flow.
Vents installed near the floor are also at greater risk of getting clogged with dirt and debris, which will restrict airflow.
What happens if there is not enough return air?
Lack of return air prevents your HVAC system from adequately heating or cooling your living environment. That has to do with how your system works. To heat or cool your home, it needs a way to deliver the air to all the rooms of the house. The supply ducts serve as the means to bring the heated or cooled air to the vents located in different rooms.
Meanwhile, the return grilles let the airflow back to the air conditioner or furnace where it is heated or cooled once more. The process goes on until the air reaches the set temperature.
If there’s not enough return air, your heating and cooling system must work double-time to bring the temperature to the desired level.
Does closing air vents make other rooms colder?
Not at all. In fact, it has the opposite effect. Closing the air vents increases pressure inside the duct system and pushes the conditioned air through cracks and gaps in the ducts. So instead of getting to the rooms, you want to cool, the air goes to areas that don’t need it.
Conclusion
High energy prices and concern about the environment lead many homeowners to look for ways to reduce power consumption. Managing your HVAC system’s energy usage by closing vents is one method you may have thought of trying. However, this could backfire and lead to higher utility bills. That’s on top of the money you’ll need to shell out to repair or replace damaged components of your HVAC system.
If you intend to lower your power consumption, you can install a zoned HVAC. This system uses dampers inside the ductwork to regulate and direct air into specific zones or rooms in your home. Each zone has a separate thermostat to manage the heating and cooling requirements of the area.
A zoned HVAC is similar to having a separate light switch for each room instead of having just one main switch to turn on all the lights in your home. You may be able to retrofit your central HVAC. Installing a ductless system is another option.
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