Lost Efficiency 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.
You should not close off the vents in unused rooms. Your duct system was designed with all those rooms factored in. Best case, your air is going to be muggy, and uncomfortable, because of all the extra humidity in the return air from those unconditioned rooms.
Blocked vents increase air pressure in your ductwork, which can create cracks and leaks. Clear vents ensure every room in your home gets good circulation so your system can work as designed. Have a piece of furniture sitting over a vent? Try using an inexpensive vent extender to direct air out into the room.
Opening doors/windows to the outside air will let warm, humid air in, mixing with the air already in your house, and making your AC system work harder. If you keep the house closed up the system only has to cool air that has already been cooled, which makes the system more efficient.
Blocking up vents is not a good idea and will lead to mold and condensation problems. You can get a 'hit and miss' vent cover which you can close if you feel a draught or its particularly cold, fresh air will still permeate the vent to some extend while closed.
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.
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.
What About Partially Closing Vents? While fully closing vents harm energy efficiency, partially closing one or two vents that are farthest away from your furnace may increase your energy savings. Unlike fully closing the vents, partially closing them still allows for proper airflow through the HVAC system.
But closing doors actually doesn't help with energy efficiency. It can actually decrease it and increase your monthly bills. The reason is that closing doors obstruct airflow in your home — and your HVAC unit needs proper air flow to function at its best. The air in the room becomes pressurized due to the obstruction.
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.
A standard but incorrect solution is closing vents. People think that if they close vents on the main floor, the system will push more cool air to the upper floor. This strategy often results in reduced cooling performance. If you have a minimal number of vents you should not close any.
Return vents are usually larger than supply vents and are in large rooms in the home. The return vents in your home help equalize the pressure that changes as your HVAC system heats or cools your home. These vents should never be fully closed because closing them off restricts airflow and strains the system.
Homes that are airtight (either because it's a new build or through weatherization efforts and renovations) require a system that will ventilate every room effortlessly, with minimal energy use. Otherwise, without mechanical ventilation, these homes become stuffy and the air inside becomes stale.
Purge ventilation
The building regulations ventilation requirements stipulate that each habitable room should have a system in place for it, although that 'system' might simply be a door or window. Alternatively, in rooms without such openings, a mechanical extract ventilation system can be used.
When doors inside are closed, pressure differentials are created. This causes your AC to work harder to ensure a steady airflow. Also, keeping the doors open can minimize the strain on your HVAC system. This translates to better energy efficiency and substantial savings.
While the idea may be to close off one area in order to make another area more comfortable, surprisingly, doing this can cause damage to your HVAC system, increase the energy needed to heat your home, and in turn, cost you more money.
The Myth: This week we are debunking the common misconception that if you close the air vents in unused rooms, it will help to lower energy costs. The truth is that doing this can actually cause more harm than good to both your energy bills and your HVAC repairs budget.
Factors for Leaving the Bedroom Door Open: Leaving the bedroom door open can improve air circulation, regulate the room's temperature, and create a more harmonious environment. Natural light from other areas of the house can enter the bedroom, enhancing the atmosphere and providing a sense of openness and connection.
Sleeping with your bedroom door closed can help maintain your desired temperature, which is crucial for a restful night's sleep. In the summer, sleeping with your bedroom door closed can help keep the air conditioning in, while in the winter, it can help keep your bedroom warm and toasty.
Shutting Heating Vents in the Summer to Conserve Energy
Leaving vents closed for extended periods can cause damage and expensive leaks. That's why we recommend rotating which vents you close every few days. Doing so will help keep your HVAC system in great shape and lower your monthly energy bill.
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.
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.
You most likely thought covering your air vents would certainly save you energy, but it does the opposite. Considering that this could damage your cooling and heating system, fractures and other damage could allow air to leave your air ducts and cost you much more in energy bills.
Closing air vents can lead to several different issues in your home: It can cause leaks in the HVAC system or make existing leaks worse. It can make your HVAC system less efficient rather than saving energy. Pressure can damage your heat exchanger, resulting in dangerous carbon monoxide leaks.
Closing air vents can lead to increased pressure in the ductwork, damage to the HVAC system, mold growth, and safety hazards, such as carbon monoxide infiltration. It's best to keep the air vents open to prevent these risks.