Sealing ductwork will make sure heated or cooled air doesn’t leak into walls, attics and crawl spaces, where it does no good.
Photo by Marcela Gara
For most people, the inner workings of the HVAC system are out of sight, out of mind. The system is ignored until something goes wrong. Understanding the basics of how a heating and cooling system works will help you create a more efficient, comfortable living space. Let’s get started.
If you have a forced air system, you have ducts. A forced air system consists of the equipment that heats or cools the air and the ductwork that moves it around the home. Your furnace, or air handler, has a fan inside that pushes the heated or cooled air through the supply ducts into the rooms. The return ducts bring air back to the furnace to be heated or cooled again and sent back through the home.
This continuous loop of supply and return is susceptible to inefficient practices and leakage.
Here are some steps you can take to keep your system running efficiently and maintain a comfortable living space.
Check your vent dampers
Make sure the air you paid to heat or cool is freely moving through the home.
As an energy efficiency expert, I wish vents were made without dampers because the feature creates the misconception they should be closed. Closing registers does not save energy. It’s more likely to cause your system to work harder, shortening its lifespan and increasing duct leakage.
If you don’t do anything else after you read this, at least check that your supply register dampers are open and not blocked by furniture or rugs throughout your home. This is easy to do and costs nothing.
Seal your ducts
If your ductwork travels through an attic, crawl space or other unconditioned—not heated or cooled—space, it could have holes, cracks or gaps that cause duct leakage. This wastes energy and money by heating or cooling spaces you don’t use.
The U.S. Department of Energy estimates 20% to 30% of the air moved through duct systems is lost due to duct leakage. You could have the most efficient heating or cooling unit available, but if your ducts leak, you are wasting energy.
In addition to wasted energy, leaky ducts can cause air-quality issues. Leaks in the return ducts can pull air into the ducts from surrounding spaces, through the furnace, and then deliver it into the home. This can introduce dust, dirt, insulation particles and other gross materials that are in your attic, crawl space or walls.
Sealing ducts can be difficult because they are hidden behind the walls, floors, and ceilings. Attics and crawl spaces can be difficult places in which to work. You can hire a professional to test your duct system for leakage with specialized equipment and to seal your ducts.
If you seal ducts yourself, do not use duct tape. I know it is hard to believe, but duct tape dries out quickly and loses its adhesion. Seal with metal tape or duct mastic specifically designed for the job.
One relatively easy place to seal is where the duct meets the floor, wall or ceiling. Remove the registers and look for cracks or gaps around the edges. Remember to wear work gloves to protect your hands.
Change your filter
The filter is on the return side of the duct system. It could be in the return registers or in the furnace. Checking your system’s filter regularly and replacing it when dirty can help you improve your heating and cooling efficiency.
When it comes to filters, my advice is buy cheap and replace often. Plus, it may be more difficult to throw away a $20 filter than a $5 filter. Save by buying filters in bulk or set up autoship for every three months.
In most cases, filters are designed to protect the furnace, not improve air quality. If you are worried about your home’s air quality, getting the ducts cleaned and sealed can help. Add an air purifier if you need additional air filtration. Look for Energy Star-rated models.
Now that you know the inner workings of your HVAC system and what it needs to run efficiently, you can improve and maintain the comfort in your home year-round.