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A Look at Sealing Ductwork

Posted by Peter Haugen on Mon, May 05, 2014 @ 01:47 PM

duct leak duct leak applying mastic applying tape

 

In a typical house, according to Energy Star, about 20 percent of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts. The result is higher utility bills and difficulty keeping the house comfortable, no matter how the thermostat is set. It’s been said that sealing ductwork is the single most effective way to improve energy efficiency. If this is true or even partially true this looks like a tremendous market.

 

From the home owners or business owners point of view sealing leaky ductwork has many benefits:

 

  1. Save Money: Leaky ducts can reduce heating and cooling system efficiency by as much as 20 percent. Sealing and insulating ducts increases efficiency, lower energy bills, and can often pay for itself in energy savings. Plus, if you’re planning to install new heating and cooling equipment, a well-designed and sealed duct system may allow you to downsize to a smaller, less costly heating and cooling system that will provide better dehumidification.

 

  1. Improved Indoor Air Quality: Fumes from household and garden chemicals, insulation particles, and dust can enter your duct system, aggravating asthma and allergy problems. Sealing ducts can help improve indoor air quality by reducing the risk of pollutants entering ducts and circulating through your home.

 

  1. Improve Safety: During normal operation, gas appliances such as water heaters, clothes dryers, and furnaces release combustion gases (like carbon monoxide) through their ventilation systems. Leaky ductwork in your heating and cooling system may cause “back drafting,” where these gases are drawn back into the living space, rather than expelled to the outdoors. Sealing leaks can minimize this risk.

 

  1. Help Protect the Environment: Energy used in our homes often comes from the burning of fossil fuels at power plants, which contributes to smog, acid rain, and climate change. Simply put, the less energy we use in our homes, the less air pollution we generate. By sealing your ducts and reducing the amount of energy necessary to comfortably heat or cool your home, you can reduce the amount of air pollution generated.

 

With these types of consumer benefits and the return on investment for the consumer, selling this service should be relatively easy. It looks like we have a tremendous market with great consumer benefits.

 

As an air duct cleaning contractor you may be asking “How do you seal ductwork”? “Is it hard”? There are several methods that can be used to seal ductwork including:

 

  1. Water based mastics (UL181) are readily available and easy to use. You can apply it with small paint brush on the outside of the ductwork and it does a good job on small leaks (under a ¼”) If the leak is ¼ “or bigger you need to use a mesh tape with the mastic for better strength and durability. There are several “how to” videos on You Tube. 

 

  1. Foil back tape with UL logo or other heat approved tapes can also be used. Avoid cloth-backed, rubber adhesive duct tape – this tends to fail quickly.

 

  1. Coatings with a high solid content and good bridging capability can be used on small leaks up to 1/8”. You would apply the coating to the inside of the ductwork. To apply coatings you typically use a cart spray system or a robotic spray system with an airless sprayer. Coatings work well in commercial HVAC systems and when the ducts are underground. Coatings and spraying systems are readily available.

 

  1. Aerosol based sealants also seal from the inside. The aerosol sealant finds the leaks and builds upon itself until the leak is sealed. This method works well in any ductwork except underground ductwork. Availability of aerosal based sealants is limited however. A Contractor must purchase a geographic territory from the owner of this technology to have access to the application equipment and the aerosol sealant. There are several You Tube videos on this method also.

 

Accessibility of the ductwork is an issue and can make duct sealing difficult. With mastic and foil tape you must have access to the ductwork. If you are working in a home ductwork in a wall cavity covered by sheetrock the ductwork is inaccessible. In this situation, sealing some of the ductwork is still better than not sealing any ductwork. Coating from the inside or using aerosol based sealants can reach most of ductwork most of the time.

 

Summary: There seems to be a tremendous market for duct sealing. There are some very good consumer benefits for sealing ductwork. There are several methods you can use to seal ductwork. Depending on accessibility it can be easy or hard to do. Is this something a professional air duct cleaning contractor should offer as a way to better serve their customers and as a way to grow the business? What’s your answer?

 

I would like to thank Mike White of Clean Air Systems of LA, Inc. for his assistance with this blog. If you have any questions about this blog article or need additional information contact: Peter Haugen, ASCS, CVI at 855-Vac-Systems, 952-808-1619 or phaugen@vacsysint.com

 

Intro to Coating & Sealing  HVAC Systems Guide

 

Tags: air duct cleaning, duct sealing, sealing ductwork, energy efficiency