You should never close your HVAC return vents, but supply vents can be adjusted to improve home comfort. In this blog, the trained professionals at Damiani's Comfort Design explain the strategy behind opening your supply vents and the dangers of keeping your return vents closed.
You should never block your air return vents. Period.
Operable cold air return vents have a lever that enables you to open or shut the vent depending on the time of year. It is a small lever that you just push up or down to control louvers, similar to the variable dashboard vents in a car.
If they are too small, airflow will be restricted and there will not be enough air circulation to heat or cool the inside of your home. Return air ducts must be sealed and unobstructed — Sealing return air ducts is just as important as sealing supply ducts.
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.
1. Openings shall not be located less than 10 feet (3048 mm) measured in any direction from an open combustion chamber or draft hood of another appliance located in the same room or space. 2. Return air shall not be taken from a hazardous or insanitary location or a refrigeration room as defined in this code.
You should never close your return vents on purpose, but it can happen accidentally. “It can happen from people not paying attention and throwing a rug over it or a couch that doesn't have feet, and they cover the return,” Smith says. Keep furniture at least 10 inches from return vents to allow proper airflow.
Here's why it is a problem: If that air isn't passing through the vent, it is being backed up in the ductwork, which causes pressure to build up within the system. This pressure can cause your system to overheat and break down.
If you have a top/bottom return vent setup, close the top vents in the winter months. Closing the top vents will make your system draw in air from the bottom vents that are at the low point in the room where cold air settles.
Dropping a mattress directly onto a floor vent will completely restrict the airflow and prevent the HVAC system from heating or cooling the space. This, in turn, can cause the HVAC system to work overtime, leading to premature wear and tear.
Parts of Your Home Are Hotter or Colder
If there's not enough return air, your living room can be 10℉+ warmer or cooler than, for example, the bedrooms.
Instead, there should be at least one return vent in every room, with two or three being ideal. If your house has only one return vent, this is not a problem — make sure to keep the doors open in every room so the air can circulate properly. Make sure there are no furniture, draperies, rugs, etc. blocking return vents.
If the return duct is too small or there are an inadequate number of return grilles, your HVAC system won't be able to return enough air to recirculate into the system. Again, it's like if you were breathing in through a straw while jogging.
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.
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.
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.
Reduced efficiency: Your HVAC system will work less efficiently if you block a return air vent. This will make the units use more energy and will raise your utility costs.
Simply because it is an investment in your indoor air quality that should also put money back in your pocket. The Department of Energy says: “Sealing your ducts to prevent leaks is even more important if the ducts are located in an unconditioned area such as an attic or crawl space.
The ductwork could be undersized or not installed properly. But it could also be as simple as a blocked air filter.
Blocking air return vents causes your system to work harder, as there is less air flow to move the air back to the furnace. This continued strain on the HVAC system can lead to a decrease in performance and more HVAC repairs down the road.
What room should return air ducts not be installed? Return air ducts should generally not be installed in rooms with high humidity or areas prone to moisture accumulation, such as bathrooms or kitchens.
Return air openings for heating, ventilation and air-conditioning systems shall comply with all of the following: 1. Openings shall not be located less than 10 feet (3048 mm) measured in any direction from an open combustion chamber or draft hood of another appliance located in the same room or space.