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An Unseen Threat: How Leaky Ducts Can Cost You

Although unseen, ductwork is fundamental to heating and cooling systems. These passageways are necessary in homes with any type of forced-air heating or central air conditioning.

Because they’re out of sight (and out of mind), you might not think too much about their role and efficiency. Yet according to Energy Star, up to a third of the air that moves through ducts could be lost to leaks, improperly sealed joints, or a lack of insulation. Yikes! The result can be higher energy bills and can even cancel out the savings you might experience from upgrading to a more efficient furnace or central air conditioner. However, there are ways to remedy this issue.

For instance, you might see benefits from resealing, adding insulation, or replacing joints themselves. This is a piece-meal approach — it usually makes more sense to hire a professional to replace the entire duct system. That’s because these improvements may prove difficult if the ducts are hidden behind drywall or above ceilings. While a sizable investment upfront, keep in mind that the chance to save up to 30 percent or more on heating and cooling costs means that this project will likely pay for itself over time.


Think Beyond Leaks

Leaks and seams are responsible for energy loss, but something called heat conduction is another factor. This issue, in combination with air leaks and gaps, can reduce the efficiency of the heating and cooling system by as much as 40 percent.

When this occurs, the heat or the cool air created by the furnace or air conditioner passes through the metal walls of the duct. This means the duct itself and the spaces directly surrounding it are heated or cooled. As a result, some conditioned air does not make it to the living spaces. Efficiency is compromised.


Should You Do it Yourself?

Some DIY moves can increase the efficiency of the duct system. For one, homeowners can seal leaks and gaps, along with adding insulation around the ducts. This can prove to be especially helpful in areas of the home that are usually cooler or warmer than the commonly used living areas, such as the attic or basement. It makes sense to do this in places where it’s easy to access the ductwork. That includes open attics and crawl spaces, unfinished basements and garages.

When the scope is greater, such as sealing hidden ductwork or taking on a complete retrofit, it’s recommended to hire a contractor. Such professionals are familiar with the nature of the work and have the equipment and expertise to install ducts.


Should You Invest in New Ductwork?

One argument for getting new ducts relates to a concept known as thermal regain. This takes advantage of heat conduction to curb energy loss. When heat is conducted through the duct walls, it warms the adjacent area. You might think this is an example of inefficiency. Conversely, it can also be a boon. If the heat filters into the living area or if it warms the surrounding spaces, it takes longer for the warmth in the living area to escape.


How Thermal Regain Helps

The most effective means to take advantage of thermal regain is to install the ducts directly in an insulated, climate-controlled space. This way, any heat or cool air that enters through the ducts is still used to condition the air in the living space. For example, this might involve the space above false ceilings or in between interior walls. Because the conducted heat enters the living space anyway, the thermal regain is 100 percent.

In attics, uninsulated basements, or crawl spaces, the benefits are not as great. Still, it may increase efficiency because it will warm the air in the nearby area. Ultimately, you’ll have a temperature barrier that will increase the amount of time it takes for the conditioned air inside the home to escape.


Safety Issues

We already addressed efficiency issues, but air quality and safety inside a home are also important factors. While gases like carbon monoxide may be pulled into a living space from a gas-powered appliance like a furnace or water heater, it’s more likely that particles and gases that are unhealthy, but not immediately fatal, will end up in the living spaces. Radon gas and trace amounts of exhaust from natural-gas-powered appliances are a few of these nasty environmental toxins.

The biggest culprits? Contaminants are drawn into the ducts by changes in pressure caused by the air-handling fan. Leaky ducts can compound pressure problems. Faulty ducts can also cause humidity to build up during the summertime in mild climates and year-round in hotter parts of the country. This dampness provides a breeding ground for mold growth. In short, these examples are proof that under-performing ductwork can lead to health and safety issues as well as put a damper on the efficiency of a home’s HVAC system.

Homeowners can conduct a quick inspection of visible ductwork to check for leaks and gaps. They can look to see if ducts are placed in uninsulated areas of the home and even decide if additional insulation is necessary. However, more in-depth efficiency tests will require the services of a specialized contractor.

Now for the good news? An HVAC specialist with the proper tools will be able to test the whole duct network for leakage. More sophisticated equipment can also help locate the leaks to see if they’re internal or external — and help determine the severity of the issue. It’s also important to measure airflow rates. This can help shed light on the performance of the system’s fan(s). Professionals perform this test with a device that measures airspeed inside the ducts. When combined, these tests can provide a window into the state of your ductwork.


Call the Pros

If you’re concerned about leaky or dirty ducts, know that a trusted HVAC contractor can offer expert insight. Depending on the nature of the issue, the technician may be able to repair or clean the ducts. However, in some cases, replacement might be the smarter choice. Regardless, we’re here to answer any questions and help you make the best choice for your home, your family’s health and budget.