Air ducts are the pathways for cooled and heated air to enter throughout the home. Simply put, they are the circulatory system of the home. Since the air duct system is hidden behind ceilings and walls, consumers often forget about the efficiency of a duct system and the important role it plays in conditioning the home’s indoor air. Duct system leaks have a large impact on energy consumption. A report by the EPA indicates that 70 percent of homes have significant duct leakage and are losing up to 30 percent of conditioned air. Energy efficiency is greatly impacted by leaking ducts.
The Causes, Pitfalls and Tests for Duct Leakage
Unfortunately, some consumers invest in a high efficiency HVAC system that is connected to a leaky ductwork system. In many cases, it would have made more sense to just install a medium efficiency unit along with duct sealing. Duct leakage can occur for a variety of reasons. It’s possible that the connection to the plenum has slipped or the round flex duct is not properly connected. Often, the joints of the ductwork itself are disconnected. These types of leaks are very common.
Sealing the ducts is even more effective than sealing the building envelope. This is because of the pressures in the air distribution system. When the HVAC system is running, the pressures are much greater, and the holes in the duct system will leak. The challenge with identifying duct leaks is that the air leaks are invisible unless you have an infrared camera. The only way to check the ductwork for leaks is to test it. Professionals often use a simple pressure test to measure airtightness of the air distribution HVAC system. Using a duct blaster, blower door or pressure pan, the total duct leakage can be measured.
Types of Air Duct Leakage Tests
A basic leakage testing system includes a device to measure building pressure, a register sealing system and a calibrated fan. Supply and return registers are sealed except for one. The calibrated fan is connected to the unsealed register and pressure is monitored. Depending on the home, some HVAC systems are completely outside of the thermal envelope while others are inside the thermal envelope. Often, a blower door test and a pressure pan test are done for those units outside of the thermal envelope. With the blower door test, all of the registers are sealed off and a measure is taken of the total leakage. With the pressure pan test, a hose is attached to the pressure pan and a pressure gauge is used. The pressure pan test in used in tandem with the blower door test to identify locations of the ductwork that are leaking. It is not a quantitative test but a qualitative one.
Methods and Types of Duct Sealing
Duct tape should never be used to seal ductwork. When used on ductwork, it just dries out and disintegrates. Today, professionals use advanced technology when sealing ducts. Some of these processes include polymer particles to stick to the edges of the leak and then stick to each other. In this respect, the leak is fixed from the inside out. This type of duct sealing is based on aerosol duct technology. The process begins with closing off the registers, and aerosolized adhesive particles are blown into the duct system. As the particles exit through the leak, they deposit on the leaks’ edges. Since many duct systems are only partially accessible, aerosol duct technology is a very practical solution. Other methods for duct sealing include mastic tape or metal tape.
How to Choose the Right Contractor for Duct Sealing Projects
If you should decide that duct sealing is not a do-it-yourself project, you may prefer to hire a professional contractor for the job. Most HVAC contractors do offer ductwork services. Here’s a list of items to look for when choosing a contractor for a duct sealing project. You’ll want to choose a professional who will:
- Do a full-inspection of the entire ductwork system, including the crawlspace, attic, garage and basement as needed.
- Complete an evaluation of the system’s return air and supply air balance. Some systems have return ducts that are too small.
- Do a complete repair of disconnected ducts, damaged ducts or straighten out flexible ducts that are tangled.
- Seal all connections and leaks with an aerosol-based sealant, metal tape or mastic tape.
- Seal all grills and registers tightly to the ducts.
- Insulate ducts in unconditioned areas using a minimum R-value of 6 duct insulation.
- Install a new filter.
- Test airflow after repairs are completed
- Ensure there is no back drafting and conduct a combustion safety test once the ducts are sealed.
HVAC Products and Services at Gentry Heating in Tryon, NC
At Gentry Heating, we carry and install top brand heating equipment with high AFUE and HSPF ratings for maximum energy efficiency. As a Carrier Factory Authorized Dealer, we are able to offer our customers HVAC systems that are engineered with the most revolutionary technology for ultimate comfort and efficient energy consumption. As a customer of Gentry Heating, you can take advantage of our low-interest financing plans and Internet coupons on services and new equipment. Be sure to call us for any of your HVAC needs.