When Should Air Conditioning Ducts Be Replaced?

ByMarc Silberberg


Mrs. Norton asks her granddaughter, Marline, to come over to her house to help her bring down her spring wardrobe from the attic. Mr. Norton has warned his wife not to dare open the attic door in his closet to go up the collapsable stairs by herself. Now that Marline is here Mrs. Norton opens the attic door and goes first with her granddaughter following, protecting her grandmother from falling. Before moving around Mrs. Norton reaches for the light switch but not in time for her to warn Marline to watch where she steps. Marline is a big girl with a heavy footprint and steps on the AC air duct pipe on the attic floor.

Marline’s grandmother does not blame her since this is the first time Marline was ever in her grandparents’ attic. Mrs. Norton looks around the room at all the ductwork on the floor of the attic and gives a sigh,” Why would anyone place the AC pipes on the floor if this is a walkable attic?” Marline feels so bad and is relieved when her grandmother hands her some duct tape to patch the small hole that was made by Marline.

“Just rip off some duct tape and patch up the hole, this is not the first time, and it won’t be the last that these stupid hoses get in the way”. Mrs. Norton explains. Humorously, Marline admits that she never knew why duct tape was called by that name since she and her friends create craft ideas from different colors and patterns of duct tape.

Mrs. Norton’s home was built over forty years ago and she was so happy when she moved in that she was finally able to have central air in her home instead of one lone air conditioner in her previous home. In her old home the air conditioner was situated in the dining room and when the heat in the house was unbearable the family would bring their pillows and blankets into the dining room to enjoy the cold relief. One or two of the children would even sleep under the dining room table where there was indeed plenty of extra space.

Marline asks innocently as she looks at the ductwork on the floor, “What are these strange silver contraptions for?” Mrs. Norton did not really have a full answer as to what AC duct pipes do exactly. She simply answered that they move the air-conditioned air all through the house. Marline commented that she thought there could be a more efficient way to circulate the air in the house instead of on the attic floor and why doesn’t her grandmother call in an air duct specialist to fix and improve this issue.

The truth is the Nortons have been diligent in calling in their AC professional each spring to check on the central AC machines. These air duct specialists do go up to the attic to make sure there are no leaks, but she is certainly not sure if they actually check the ductwork for holes. When Mr. Norton came home later in the day she posed this question to her husband. Mr. Norton could not give her an answer since he sincerely trusts his AC guy and never really asked him what he does up in the attic when he comes.

The Nortons’ AC professional goes into each room to check the air vents on the ceiling of each room to make sure cold air is blowing. A good idea that he gave them was to stick a piece of ribbon on each room vent to check on the air flow ever so often. This was such a help for Nortons when one of the bedrooms did not feel cool. They noticed that the ribbon was not moving meaning the vent was not bringing cold air into the room. The air vent has an on and off piece that can be switched on or off if the room got too cold and they recalled that a elderly guest had slept there recently and probably decided to close the vent. The Nortons were proud of their discovery and did not need to call in the AC guy unnecessarily.

At dinner that night the Nortons discussed the age and condition of the ductwork in their home and if there was a need for replacement. They have replaced their outdoor AC units a couple of times but never discussed a replacement with their HVAC professional.

How Often Should Ductwork be Replaced?

Ductwork ideally should be replaced every ten to fifteen years although we doubt anyone does it that often. Twenty years seems to be the general aging and disintegrating time when a duct professional would certainly insist on replacement. Some signs that they do need replacement are a significant rise in the electrical bill, excess dust, a decrease in the cooling power of your units and strange noises coming from the room vents. Noise may indicate that the ducts have loose connections.

The materials that were used in the Norton’s ductwork forty years ago are not the same that are being used today. Fiberglass ductwork is better than metal but after ten to fifteen years can corrode and ideally should be replaced. Other factors that could cause the ductwork to deteriorate are the decomposing of the sealants used to secure the HVAC system and sneezing and coughing by members of the household.

As in the Norton’s case they were able to have a professional come in and seal the duct leaks and for the time being did not opt for new ducts; fixing the leaks with heated caulk and cleaning the air ducts solved the problem for now. Of course, down the road, they will have to deal with a more permanent solution for their duct issues but are leaving it for now. Seniors such as the Nortons do not know how long they will be living in their home since some of their friends are choosing to sell their houses and move into apartments or purchase condos. The next owners of their home will probably opt for revamping the entire AC system.

Is the Attic a Good Place for The AC Ducts?

There are conflicting opinions about whether the attic is the ideal place to put your AC duct system. Dave Roberts, who is an engineer for NREL (National Renewable Energy Lab) researched the location of the attic as a venue for the ductwork if the attic is unfinished. An attic gets quite warm in the summer even with an attic fan. Just try going up to your attic when the temperature rises outside, and you will be hit with a gust of hot air. Why heat up the air more than necessary for it to have to cool down substantially as it enters the main part of the home? Scientifically, heat transferring speed depends on how much heat there is as the air is transferred from warmer to colder.

Another disadvantage of having the AC equipment upstairs in the unfinished attic then with the ductwork is on the floor anyone going up there for any reason other than a HVAC professional can step on the ducts and puncture them as the granddaughter in the story above.

According to a second opinion, an easy to get to attic is a contractor’s dream for a HVAC ductwork assignment. They do agree that the attic does get quite warm but advise that by spending some extra money on heavy insulation (costing between$1,450 to $4,650) it’s still a good option. The cost will depend on the attic size. Technicians qualify that the ease of a pull-down attic door and extra free space makes the extra cost of insulating the attic worthwhile.

Those of this second opinion discourages homeowners from opting to put the HVAC paraphernalia in the crawl space or basement of the home. Technicians may have to use specific tools to work in the small, cramped space of a crawl space and they cannot stand up in a crawl space making it backbreaking work.

An unfinished basement may be a good option as well to put the major pieces of the HVAC system in place. The basement of the house has the coldest temperatures and as long as it’s empty could be a good idea. However, if it’s a finished basement that is already part of an occupied home then the cost for the ductwork will go up from $1,300 to $4,500 since walls and ceilings need to be opened.

Another obvious question about putting new ductwork is what about the walls? Will they have to be opened? Or is there room in the closets instead? Using the closets may take away precious space that the family needs for their stuff. However, if walls have to be opened your expenses will increase because not only do the workers have to open the walls but they will have to repair them as well.

Can Quality Duct Cleaning Do The Trick?

We have written about the need to replace AC ductwork in certain instances, especially in old residences. However, if a homeowner calls an air duct specialist on a regular basis there is a good chance of his or her HVAC ducts lasting longer. Even if there is dust, noise, and other indicators of trouble a reliable air quality specialist will be able to clean the ducts and avoid the need for duct replacement for a longer period of time.

Final Words

Most homeowners do not know what’s going on with their air ducts in the attic. With new construction the contractor will determine the most practical place to lay the air duct pipes. On the other hand, with older homes wanting the addition of central air the contractor will have to make a determination based on his experience and the layout of the home. Most folks end up having their AC duct installation in the attic out of harm’s way. However, if you do use your attic for storage make sure you have good lighting so no one will accidentally step on the ductwork.

Most folks are diligent when it comes to keeping their car up to date. Your car needs to be serviced regularly besides watching the gas gauge and similarly your HVAC system has to be serviced regularly as well. By keeping an eye on your AC system there will be a better chance of not needing to replace your ductwork and instead having it cleaned on a regular basis.

If you notice your AC not working properly, meaning not getting cool enough or hearing strange noises coming from one or more of the room vents, don’t jump to the conclusion that your ductwork needs replacement. Instead, call a reliable air quality specialist who deals with HVAC systems, and you may be happily surprised that your system just needed good cleaning.

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