Perhaps you’ve noticed that one of the rooms in your home or apartment remains noticeably colder in winter than the others.
When you check the heating vent in that room—to make sure it’s not closed or blocked by furniture or other obstacles—you find that the HVAC vent is wide open. No problem there. And when you check the vents in other rooms, you discover that heat is flowing normally from those vents. So what’s the issue?
Following are several common reasons why a single air vent is putting out little to no air:
Leaky, Poorly Connected Ductwork
According to ENERGY STAR®, “in a typical house … about 20 to 30 percent of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts.”
One clue that your house or apartment has poorly performing ducts is a room that is difficult to heat (or cool). Improving ductwork can fix this problem, however, because ducts are typically concealed in walls, ceilings, attics, and basements, making these improvements easier said than done.
If you do find leaks or poor connections en route to the problem vent, ENERGY STAR recommends using mastic sealant or metal tape to seal the problem areas, emphasizing that you should, “Never use duct tape, as it is not long-lasting.”
In addition, ENERGY STAR recommends you “make sure that the connections at vents and registers are well-sealed where they meet the floors, walls, and ceiling. These are common locations to find leaks and disconnected ductwork.”
Disconnected Ducts
A disconnected duct—which can be a result of faulty installation—is an even bigger problem, as it may result in no airflow to a vent. If the duct is disconnected—and you can see/find the disconnect—you can re-fasten it using sheet metal screws and seal the joint.
Crushed or Kinked Ducts
Similarly, you may find a crushed or kinked duct—again, often a result of faulty installation. In some cases a kinked duct may simply be straightened out, thereby eliminating the airflow restriction, but in most cases a crushed or kinked duct will have tears or won’t hold its shape and will need to be replaced.
Closed Dampers
Another possible issue is that you have a damper (dampers are valves in your ducts that control airflow) that is closed or almost shut. A damper can be useful for cutting off the heat to an unused room or to help regulate temperature to a specific room, but it’s self-defeating if you don’t know it’s closed or don’t want it closed.
Duct Sealing and Inspection
If you’d like further information about common duct sealing problems & solutions, as well as advice on working with a commercial contractor on duct improvement projects, we encourage you to consult the U.S. Environmental Protection Agency’s Duct Sealing brochure.
Still Need Help?
If you have any questions or concerns about your duct work and whether it’s causing you to sacrifice comfort (and money), we encourage you to refer to our heating maintenance page or call us at 615-469-5965. Jewell Mechanical provides residential and commercial air conditioning and heating services for Nashville Metro Davidson County.
Helpful HVAC Resources:
Residential Air Conditioning Services
Free Surveys for Maintenance, Unit Replacements and 2nd Opinions