The repercussions of a blocked air vent can extend beyond just the unit's inefficiency, actually causing it to break down over time. The furnace's heat exchanger and the air conditioner's cooling coils rely on air to regulate their temperatures. If this air level is reduced, the heat exchanger can overheat.
The myth behind closing your vents
Unfortunately, this is a common myth. Closing HVAC circulation to certain rooms may result in issues with your ducts. It creates a less efficient heating and cooling system and can be dangerous.
Most HVAC systems will function fine if a few vents are closed, but closing many vents at the same time is not advised. If you're closing vents for comfort, it's best if you only close them temporarily.
While blocking air bricks may seem like a good way to keep the cold out, it can cause more harm than good. Covering these vital vents stops fresh air from flowing into your home. This lack of airflow leads to damp and moisture buildup. Damp conditions are perfect for wood rot and mould growth.
If these air return systems are obstructed, not only will you block the proper airflow and create stuffiness in the rooms of your house, but you will have uneven cooling or heating, lack of proper filtration, and potentially higher energy bills.
Significant Fire Hazard
It is not widely known, but if there are not enough open vents in your home for heat to escape, it can build up in the ductwork and start a fire.
Ensure that all the ductwork connections are sealed properly on the interior and exterior points of the ductwork. You can seal gaps using metal tape, foaming insulation spray, or mastic sealant. You do not need to remove any existing sealant and may build up the sealant over top of any current filler.
You will probably see one of two things - a gap between the inner and outer skins of the walls or the equivalent to a duct to the outside. If there is a gap between between both skins then you should be ok to cover up the inner skin. if it is the equivalent of a duct then I would block up the outside as well.
Closing one or more vents can disrupt the airflow and temperature balance of the whole system. This can cause issues such as insufficient airflow in rooms far away from the blower or excessive airflow in rooms closest to the blower.
To utilize your supply vents strategically, we suggest: Closing supply vents in higher locations by your ceilings while opening lower ones on floors or close to baseboards. Doing this will direct more warm air to the floor, where it will rise to heat the whole space.
First, heat rises, so it's normal for the second floor of a home to get hotter than the main floor.
In short, the answer to this question is no. 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.
Should I Block Cold Air Return Vents In The Summer? You should never block your air return vents. Period.
It's not a good idea to close vents in unused rooms
If you close vents in an unused room, then the airflow that would have gone into that room will be redirected into another part of the system.
A build up of pressure can be caused by covered vents. This could lead to a cracked heat exchanger which in turn can lead to leaking carbon monoxide. Covering your vents can damage your HVAC system and cause cracks that could allow air to escape your ducts. This can lead to higher energy bills.
Option Three, Temporary Vent Block Off:
This can be done by taking a small trash bag, stuffing it with insulation, then placing it within the vented area. You never want to push unprotected insulation to the vent as any direct moisture contact from the outside will ruin its insulating properties.
Block Off the Vent: You can block the vent by placing a piece of furniture at the opening or purchasing a magnetic damper that's strong enough to stick to the steel on the wall or ceiling. Plastic sheeting can be placed over the opening as well. You can also install a vent grille filter.
May Cause Mold Growth
A closed vent in an unused room can cause mold and mildew growth. Worse yet, those spores can then make their way into other parts of the house since the room isn't sealed airtight.
Dampers are an important part of HVAC systems. Consider a dam, for example. When closed, a damper prevents the air from going across it like a dam does with water. HVAC dampers are an important part of your zoning system.
This is a terrible scenario for any homeowner, but it can be especially dire for allergy and asthma sufferers. If you're blocking the vents with upholstered furniture—say, the wall vent is right in the middle of the only wall suitable for your couch—you're setting your couch up to be a mold and mildew nest.
When air can not move effectively, a pressure buildup can get created inside your air ducts and also your HVAC device. This will inevitably produce less airflow as well as cause your heat exchanger to split which will certainly enable carbon monoxide gas to leak into your residence. You might create mold and mildew.
Temperature issues: A vent under the bed can make the mattress uncomfortably hot or cold, disrupting sleep quality and potentially affecting overall health.
Keep your home ventilated
Open windows at least once a day, keep window trickle vents open, and air vents uncovered. It's important that air can move through your home as ventilation is one of the best ways to avoid mould, as flowing air means spores can't settle somewhere and absorb water.
The heat exchanger uses coils to transfer heat from the ignited gas to the air. When cold air blows from a furnace the heat exchanger, furnace burner, or exhaust are likely the cause. This may be due to dirty components, broken parts, or the many safety mechanisms within the gas system.