Unsealed ductWhat is unsealed duct work?

As your heart needs arteries and veins for carrying blood around your body, similarly, your heating and AC equipment requires duct work to spread out the conditioned air throughout the house. However in most homes, roughly 20 to 30% of the air that flows through the duct work escapes into the attic or crawlspace depending on its location through leaks in your unsealed duct work and system. The unsealed or leaky duct work can causes many problems with your system and increases your bills dramatically. Sealing of ducts is extremely important, however the level of importance goes up, if the ducts are located in an unconditioned area such as an attic, garage or a crawl space.

What causes duct leakage?Duct sealing needed

• Harsh weather conditions in unconditioned air spaces, like our Dallas area 160 degree attics

• The ducts become torn & worn out from excessive use in long Texas summers

• Improper installation, Laying on attic floors, insufficient insulation and improper sizing

• Damage caused by insects, pests, rodents and contractors stepping, sitting or crawling over.

hot attic airDisadvantages of unsealed ducts:

• Enormous waste of energy, since about 10-30% of the of an average unit’s output is wasted due to duct leakages which wouldn’t occur if ducts are sealed properly. Energy losses can also occur when the central furnace fan is not running or operational. There are five ways through which an unsealed duct causes energy losses:

– Conduction: Hot 160 degree attic air outside the poorly insulated or unsealed ducts heats the duct walls, which in turn causes the cold air inside the ducts to become warmer than it should, causing your unit to work longer and harder to cool your home

– Air leakage: At times, the cause of these air leaks could be damaged or poorly connected unsealed ducts that allow conditioned air to escape into the attic or crawlspace instead of going into your home.

– Leaky supply ducts: In this case, the supply ducts are leaking, but the return ducts are fully intact. This causes energy loss in two ways; the energy loss caused, which does not go into the rooms and/or extra amount of energy required to heat up the cold air that leaked inside the house.

– Leaky return ducts: This is the opposite case where the return ducts hot air in summer or cold air in winter to get pulled into the system while the supply ducts remain intact. Since the return ducts operate at a higher pressure than the house supply ducts or the outside, cold air or hot air depending on season from the outside surroundings is pulled into this return duct. What happens then is that this cold air along with the air that came into the house through return registers, is heated in the furnace, which causes an imbalance since the amount or air that came in the house through the supply ducts becomes greater than what the return ducts took away from the house. To balance it out, cold air is pulled in and warm air leaks out.

duct 2• Unsealed ducts allow dirty and unconditioned air to be pulled back inside the house causing the air around you, to become polluted and turning into a health hazard. This dirty air can also cause instill dangerous dusts and microbes which can lead to lung and respiratory diseases. Dirty air can cause the inside of your system to age and fail prematurely.

• The energy waste caused due to unsealed ducts means your system runs longer than it should

• Rooms become stuffy.

• High summer and winter utility bills.

• Indoor temperature variations.

• Decreases life of heating/cooling systems.

How to seal a duct?

Since the ducts are often located inside walls, garages, attics and basements- it becomes difficult to repair them, but there’s always something that you can do about a situation. Firstly, a thorough investigation is to be carried about the location and intensity of the duct leakage. You can either choose to seal the ducts inside your house, on your own, or you can hire a professional, such as Efficient Home Solutions, to do this for you.


Even when your unsealed ducts are not damaged or worn out, they can be a cause for air leaks which again leads to all the problems stated above, such as high energy consumption, health risks, increased electricity expenses, etc. Effective duct sealing has a direct impact on your wallet, health, as well as on the environment as a whole.

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