Is it ok to Cover a Heating Vent? [When to & When Not to]

Is it ok to Cover a Heating Vent? The waste of energy and money spent heating unused rooms is quite annoying.

Fortunately, some heating systems will have special levers that direct heat from some vents to other areas. So what can you do in this situation? Can I cover the heating vent to prevent heat from entering a specific room? What about an inadvertent blockage, a bed covering the vents, or something like that?    

The short answer is that— blocking or covering the heating vent is generally safe if done correctly. A good heating system of any type will have sufficient power reserve to account for a blocked vent and adjust the heat level and airflow between your other vents.

This can result in both increased heating through other vents in the system and reduced energy costs.

What about risk? As with anything related to heating systems, you should always know what you are doing and look for potential problems.

Here’s a step-by-step guide on “Is it ok to Cover a Heating Vent?”

How to Cover the Vents Safely : Do and Don’s

Check the Entire Heating System for Malfunctions

In any case, you need to do full annual maintenance so that you can do it sooner. It is important to check the entire system as problems can occur anywhere after redirecting the airflow.

Take the Amount of Airflow into Account

If the heating systems only have three vents, blocking one will increase the flow through the other two by 50%. If you have 5 vents, blocking one will increase the flow through the other 4 by one-fourth times. The more vents you have, the easier it will be to block one of them. If there are 7-8 or more vents, you can even safely block 2 vents.

All in all, while it’s almost always safe to block the vent, make sure the rest of your system can work fine after that.

Choose a Cover Made of Heat-resistant Material

As we said, some systems have built-in levers that activate the internal metal covers of each air vent. If there are no built-in covers of this type, you will have to make your own cover.


How Do You Safely Cover the Vent?

magnetic vent covers

Some companies make magnetic vent covers for any system. Alternatively, you can create the cover yourself. Just be sure to use heat-resistant material. Nested pieces of cardboard wrapped in aluminum foil can act like plywood. Use magnets or small metal weights to hold the cover in place.

DO NOT try to block the air vent with bare wood. Many homeowners make the mistake of blocking the vents with furniture such as beds, cupboards, etc. It is not a good idea.   

To make sure everything is running smoothly and to avoid a fire hazard to the vent, perform routine checks on both the obstructed vent and the rest of the heating system.

Increased Pressure

Your heating and air conditioning devices have been configured to the specific size of your home. When you close the vents or block them with furniture, the same amount of air is pushed through the ventilation system, but at a higher pressure due to the limited possibilities of airflow.


Not only does it force the HVAC system to work harder, shortening its life span, it also produces frozen A / C coils, overheated furnaces, cracked heat exchangers, and leaky duct systems. These problems come with both a danger to the home and a high price to pay for the repair.

Mold and Moisture

Due to the humidity, the moisture will build up behind the blocked vent, causing not only mold and mildew contamination but also air blowing throughout your home. This is a tragic scenario for any homeowner, but it can be especially severe for people with allergies and asthma.


If you block the vents with upholstered furniture, let’s say the vent is right in the center of the only suitable wall for your sofa, you are setting the sofa up as a nest of mold and mildew. This possibility is not limited to upholstered and soft furniture. Rugs are also an excellent breeding ground for mold and mildew, as is wooden furniture.

Fire Hazard

Perhaps the most obvious (and most dangerous) effect of blocking a vent is that it will cause a fire. How? When you force your system to overwork, as mentioned in our first point, you are putting your stove at high risk of catching fire.

While you should never say never, blocking radiator vents to divert heat into your home is usually a sure-fire way to save money by increasing energy efficiency. A major failure of the built-in safety systems would be enough for the heat inside the blocked ventilation box to become hot enough to create a fire hazard.

That said, there are many ways to block heat from unused vents, divert it and increase heat production in the area where you need it most.


Most central heating and cooling systems have interconnected ducts that feed at least one vent in each room, and sometimes several. Whether it’s to reduce heating costs or simply direct the heat to areas where it’s not needed, blocking one or more vents in unused rooms or low traffic corridors is a completely safe alternative.

In many cases, this is as simple as moving a lever on the diffuser itself that moves the louver assembly over the opening.


If there are no sliding covers on your vents or the mechanism is malfunctioning, there is at least one company,, that sells a simple magnetic vent cover that can be placed on any vents that need to be closed. You can also build your own cover from almost any heat-resistant material. Plywood is another option.

Forwarding/ Blocking

Blocking one or more vents in your home works quite well, increasing the amount of heat in areas where you may need it most. For example, let’s say your guest room remains empty all winter. Keeping it warm is not necessary when you can increase the heat supply to rooms that are used intensively in winters, such as the living room or kitchen. As long as the heating system is working properly, there is no need to worry that blocked vents will be a safety hazard.

When to & When Not to

Keep in mind that blocking most of the vents in your heating system would never be a good idea. The heater is designed to work with specific air circulation. However, obstructing one or two outlets on a system that has ten or more presents little risk of a hazard, although it would be wise to monitor blocked areas, as well as the heater for the first few days after the heat, is redirected. to make sure there are no problems. Ultimately, this is a safe modification.

We can see it happening all the time. Homeowners call us because their home is adequately heated or cooled and believe there is a serious problem with their HVAC system. Eventually, we find that their vents are closed or blocked.

Sometimes people accidentally block the vents when moving furniture. Other times, people intentionally close the vents with the intention of changing the temperature in the house. This will never work – blocking the vents will only increase the chances of an HVAC repair being required.

Reasons Why You Shouldn’t Cover the Vents

  1. Changes the airflow in the system
    Air must flow freely through the HVAC unit to function properly. If you close the vents, the excess air will be forced to flow in one direction, damaging the device.
  2.  Waste your money   
    If you restrict or block the air in one room in your home, your system will have to work twice as hard to regulate the temperature in other rooms. This will increase your utility bill as the system runs twice as long.
  3. It may damage the heat exchanger
    There will inevitably be an increase in air pressure if you block the flow of air from the vents. This leads to problems with the heat exchanger – it will break and may emit carbon monoxide.
  4. It may cause problems with the air duct system
    As more air passes through the ducts to reach a given room, the ducts will wear out faster. And if your home has old wiring, your chances are even greater!

Final Words

Hope now it is clear to you, is it ok to cover a heating vent? You understand when to or when not to cover a heating vent. Before investing in a new indoor air quality system, talk to our experts to make sure you have made the right purchase. Our technicians are waiting on the second line to help you choose the right solution that best suits your individual needs.

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