10 Ways To Improve Ducts In An Unconditioned Attic

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Gina Napsin
June 23, 2024
Air Duct Cleaning
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Attic ductwork may not be the best option when constructing an HVAC system, but if you are retrofitting an older house or putting ducting in a home without a gap between the floors, you might not have any other alternatives. Most people know that your home's ductwork and HVAC system should be in a conditioned space, and studies show that ducts in an unconditioned space could be 25% less efficient in cooling your home, especially in hotter climates. Although many newly built homes that pass duct testing are tightly sealed, the truth is that many duct systems are leaking, and unbalanced duct leakage causes more issues than losses related to the leak.
But what can you do if you install ducts in an attic without air conditioning? They may already have ductwork in the attic if you're purchasing a tract house. You may be replacing an HVAC system in an unconditioned attic, and you cannot afford to encapsulate the attic—making the building enclosure to the roofline.

What Is Ductwork

First, let's learn what ductwork is. Ductwork is tubing that runs from your HVAC air handler unit to various vents throughout your home. It is covered with insulation to prevent it from deteriorating and creating problems for the air handler. The ductwork's function is to distribute hot or cold air throughout the house so that you may chill it down or heat it as needed. Spray foam should be used to air seal your attic's ducts before they are blown-in insulation.
The material that makes up ducts is a metallic alloy. Despite being robust, they are far more prone to rust and disintegrate over time due to exposure to the elements and oxidation. Here are some ways to improve your ducts in an unconditioned attic.

Don't Put Ducts On The Roof Underside

The roof underside is the attic area that gets the most heat on a warm day. You can't keep your hand against it when it's that hot. Be aware that some contractors feel it's acceptable to strap a duct right up against the deck, especially since the heat from the duct can pierce the insulating jacket or the duct itself, and the roofing nails going through the decking can damage the ductwork.

Position Your Ducts On The Lower Part of The Attic

Attics may get exceedingly warm. An uncooled attic can reach temperatures of up to 120° F or perhaps a little more on a hot summer day. Attics aren't always heated, though, something you might not be aware of. The warmest air is found in an attic, and the area closest to the attic level is the coolest. The attic floor is where those ducts should be because it has the lowest temperature.

Use a Horizontal Air Handler

The air handler should be low in the attic because you want the ductwork to be low in an unconditioned attic. Because you choose a vertical air handler, you're forcing chilly air higher up in the attic throughout the summer. For the same reason that ducts should be low in the attic, a horizontal air handler in an unconditioned attic should be as low as feasible.

Seal Your Ducts Tightly

When ducts are located in an unconditioned attic, duct leakage can be quite problematic. Even worse is unbalanced duct leaking, and mastic in large amounts is used to seal them. It's time to seal all the duct seams if you discover significant leaks in your ductwork. Duct sealing is one of the best ways to increase in-home duct efficiency, according to Energy.gov.

Insulate The Ducts and Air Handler

Insulation must be applied if exposed ducting is located in an unconditioned area. Any heat or cold leaking from ducts goes to heated or cooled places. Thus, losses in climate-controlled spaces are costly and wasteful in energy use.
You may insulate your ducts if temperature and moisture are issues for your attic's ductwork. Have a licensed air duct technician inspect your ductwork for leaks before investing in an expensive duct insulation installation. Once you've determined that your ducts are the issue, you have a few choices.
Get an air duct replacement or repair if your ducts leak due to damage or cracks. Add regular fiberglass insulation to the exterior of the vents if insulation is the issue. Another solution to the problem of excessive heat transmission between your attic's unconditioned region and your ducts is to seal them with spray insulation.

Increase The Airflow In The Ducts

This recommendation helps in preserving comfort inside the house. Slower flowing air in conditioned areas decreases airflow resistance, which is beneficial. When ducts are present in an unconditioned attic, the air flowing in the ductwork warms up in the summer. The temperature of the conditioned air will rise the more slowly the air flows through the duct. Faster air movement disperses heat over a larger air volume with a smaller temperature rise per cubic foot. Therefore, construct the duct system for quicker air.

Keep your Attic Cool

Maintaining a colder attic is another technique to lessen heat transfer into your ductwork from a hot, uncooled attic. The easiest way to keep your attic cool is to use a reflective roof to block the heat from entering before it can do so. Installing a radiant barrier beneath the roof deck would be a suitable second option. Utilizing powered attic ventilators would be an exceedingly terrible decision. Install passive vents instead, holes in the roof that let hot air out, such as gable, soffit, and ridge vents.

Expand The Attic

You can only condition part of the attic or crawl area to increase the conditioned space, and just enough room may be added to fit the ducting. Plenum roof trusses, which are intended to accept ductwork and create a chase in the attic floor, are available for residences with eight-foot ceilings.
In each scenario, the building must be as airtight as feasible. After the HVAC system is installed, this can need more work from the building team in some circumstances. Of course, the conditioned space's duct seams must also be sealed.

Watch Out For Mold

The heat carries moisture into the attic as it rises through your house. Proper attic ventilation can assist with this problem, but condensation may build up on the comparatively chilly HVAC ducting before the moisture-filled air is forced out of the area. The ventilation system in your attic can no longer effectively remove the moisture after it condenses from the air, and mold can start to grow as a result.
Like in the case of high attic temperatures, this issue may be diminished or resolved by adequately insulating and closing your ducts. Make sure the outer surface of the ducting stays as near to room temperature as you can without heating the air within. Condensation may be removed, and mold prevented from growing in your attic by lowering the temperature differential.

Make Sure To Get Frequent Cleaning and Inspection

Regarding heat and condensation, your attic is one of many areas you need to be concerned about. Your ductwork may become a breeding ground for mold if warm air gets inside it. The air quality in your house may suffer due to this moldy atmosphere, and severe health problems may result.
You may identify typical issues that allow warm, damp air to enter your ducts by doing routine inspections of the ducting in your attic. Similarly, keep your ductwork clean regularly to prevent mold, dust, and allergies from settling in your HVAC system.

Is Duct Cleaning Actually Worth It?

There is currently no evidence to support the claim that regular duct cleaning enhances indoor air quality or lowers dust levels in homes. However, there is proof that filthy motors, air handling units, and heating and cooling coils can reduce the effectiveness of your HVAC system.
Even though it might not seem necessary, there are situations in which cleaning the HVAC system and ductwork may be beneficial. EPA suggests only clean HVAC systems and ducts if they are heavily contaminated.

What happens if you don't clean your air ducts?

Duct cleaning is harmless if done correctly. However, it should be on your routine or annual house maintenance list. If you leave your ductwork dirty and contaminated, it could cause several health issues for you and your family probably. You probably don't need to have your ducts and HVAC system cleaned unless:
Renovation: If you've renovated your house, you might need to clean the ductwork, especially if asbestos, lead, or dust gathers. Unsealed ducting may become a home for hazardous dust and debris.
Animals: Remove the animals and clean the ductwork and HVAC unit if there is evidence of an animal infestation or nesting in your ducts or HVAC system.
Mold: If there is noticeable mold growth inside the ductwork, clean the ducts and the HVAC system.
Impurities: If the room has an odd odor, obvious debris, pet hair, or other contaminants, clean the ducts. Call an air duct cleaning technician if these are still there after you've cleaned and vacuumed the registers.
Illnesses: If a family member is experiencing an allergy-related disease that cannot be explained and you have exhausted all other options to decontaminate your house, clean your ducts to determine whether the HVAC system is to blame.
When you need your HVAC serviced and repaired. It's crucial to know who to hire in this situation. Ensure that the ductwork is done correctly and will endure as long as you do in the house. You can trust the ducts to function for a while as long as pests and rats don't devour them. Call the duct work cleaning service in your area. Who should you call for AC duct cleaning services? You should also contact Home Alliance for HVAC maintenance. Book a service with us today!