How to Stop Condensation on Air Ducts? Is it A Sign of AC Failure?

Knowing how to stop condensation on air ducts is crucial since ductworks sweating can cause some serious damage if left unattended.

AC ducts

Condensation on AC ducts sounds like bad news. But it isn’t always necessarily the end of the world for your air conditioner’s valuable life.

Ductwork sweating is a pretty common issue that nearly all homeowners face. Fortunately, it’s also very easy to fix.

But before we get into how to stop condensation on air ducts, let us first delve into what ductwork sweating is and what causes it.

What Is Air Conditioner Ductwork?

Air conditioner ductwork

Your air conditioner’s ductwork is a network of ducts that distributes conditioned air from your central air conditioning system to your home. This network transfers air from the air vents to the main cooling or heating unit and back.

Ducts in your home can be made of sheet metal, fiberglass, or fiberboard. It’s important to know what type of ducts your home has since this can impact whether or not ductwork sweating should concern you.

Older homes generally have a metal ductwork system. The other type of ductwork is flexible ducts. These consist of a plastic tube reinforced with wire and insulation. Ductwork sweating is more likely to occur on metal ductwork, especially if they aren’t adequately insulated.

However, flexible ducts aren’t entirely safe either. Before we explain why let’s first talk about what condensation is.

What Is Condensation?

Condensation on soft drink cans

Imagine it’s summer, and you’ve got a can of cold beer in the fridge. You take it out, and immediately notice that water droplets start forming on the cold metal can.

The science here is very simple!

Condensation is the process in which water vapor becomes liquid. Cold air cannot hold as much moisture as warm air does. When warm moisture-filled air meets the cold metal can, it cools down. Resultantly, the humidity in the air condenses into water droplets. It is the reverse process of evaporation.

The same process causes condensation on AC ducts too. Your air conditioner ductwork is cold due to the cold air passing through it. So naturally, when the warmer surrounding air comes in contact with these cooler ducts, you end up with excessive ductwork sweating.

Although that is the most common cause behind ductwork sweating, it isn’t the only culprit. There are several other reasons why your ductwork might be sweating but first, let’s see why you need to pay attention to this issue.

How Is Condensation on AC Ducts Harmful?

Why should you worry about how to stop condensation on air ducts? It’s true that a small amount of ductwork sweating won’t cause you irreparable damage. However, if you’re starting to notice plenty of condensation on your air ducts, it’s time to take action!

Here’s why:

1. Ductwork Sweating Causes Damage to Insulation

Condensation on AC ducts will eventually drip down onto your home’s insulation. The water drips can compress the insulation, affect its R-value, and lower its efficiency with time. Without proper insulation, you’ll be looking at higher energy costs than normal. Another drawback is that as your insulation material gets wet, it becomes heavy. In some cases, it may lead to ceiling leaks or subsequent collapse.

2. Sweaty Air Ducts Add to High Indoor Humidity

High humidity can be harmful to your body as well as your home. Ductwork sweating adds excess moisture to the air inside the house, making it far less comfortable. High indoor humidity causes damage to wood floors, wallpaper, paint and will cause bad odors. These repairs can often be very costly.

3. Mildew and Mold Growth

Mold and mildew thrive in warm and moist places. Excessive indoor moisture levels caused by condensation on AC ducts provide the ideal conditions for mold to grow.

Mold can also damage structural components around your home since they eat through anything they grow on. This includes furniture around your home and the wood in your home’s structure. Moreover, mold spores can harm your indoor air quality and trigger allergies.

If you see mold in your air ducts, this guide will help you figure out what to do next.

4. Water Damage to Structural Elements

Water and wood don’t go well together. According to the National Association of Home Builders, 90% of the houses built in 2019 were wood-framed. As a result, condensation on AC ducts will eventually make its way into the structural elements of your home and can result in decaying and corrosion. Not only can this cause your house to lose thermal capacity in the short run, but it can also compromise your home’s structure. In addition, excessive ductwork sweating can lead to water dripping from your ceilings and leave stains.

What Causes Condensation in Air Ducts?

Ductwork sweating is fairly common in areas with a warmer climate. Once we know what causes this issue, it will be easier to figure out how to stop condensation on air ducts.

1. Mechanical Problems with Your HVAC Unit

If you see excessive sweating around your ducts, conduct a general inspection to look out for any technical issues with your HVAC system. For example, pay attention to any strange AC noises, foul smell from your air conditioner, weak airflow, leaking ducts, etc. Any such issue may lead to improper functioning of your unit, leading to condensation build-up on ductwork.

2. Poor Insulation

Poorly insulated ductwork

As mentioned above, the primary cause for condensation on AC ducts is the temperature difference between cooler air inside your ducts and the warmer air outside. Insulation can reduce this issue by creating a barrier around the ductwork to keep the warmer air away.

Even if you have insulation around your ducts, it might be inadequate, to begin with, or might wear out over time. Worn-out insulation can have tears around it that can make the condensation issue much worse. Some types of insulation are water absorbent and will soak up the condensation, making them less effective.

While this is common for metal ductwork, flexible ducts might also sweat when the connection points between these ducts are improperly sealed. This can lead to duct leakages and thus ductwork sweating.

3. Excessive Moisture in the Air

One of the most common causes of ductwork sweating is excess moisture in the air. With more moisture in the air, there’s going to be more moisture collecting on your ductwork. The ideal indoor humidity levels vary around 40% and 60%. Maintaining this perfect humidity level is important for preventing ductwork sweating and for your health and comfort.

There can be several things causing high humidity levels, such as damp basements, plumbing leaks, drying your clothes indoors, or having poor ventilation. The higher the relative humidity in your home, the greater the chances of condensation on your AC ducts.

4. Dirty Air Filters or Blocked Ducts

Ductwork sweating can be indicative of the fact that the air circulation in your ducts isn’t efficient.

For example, there could be something blocking your ductwork, your AC filter could be filthy, or the MERV Rating on the filter you’re using could be too high.

To ensure proper airflow, replace your air filters every three months, even if you don’t see condensation on AC ducts. Doing so also improves the efficiency of your air conditioner.

5. Leaky Ducts

Leaky ducts impact your air conditioner’s performance and can also cause condensation on AC ducts. Air conditioner ductwork has pipes connected and sealed together. With time, these seals wear out and give way to air leaks.

While these pipes might have insulation around them, the cold air leaking into the insulation affects its performance. Air leakages also prevent the efficient circulation of air which can intensify ductwork sweating.

6. Improper Installation

Another common cause for condensation on AC ducts is if they aren’t hung properly or are touching each other. When ducts touch each other, they create cold spots where condensation can occur. Proper installation is also important when your ductwork is installed in the attic since installation can affect how well the insulation performs.

7. Warm Attic

If your air conditioner ductwork is in your attic, the high temperature might be a possible culprit behind ductwork sweating in your home.

For example, on a hot summer day when it’s 90 degrees outside, your attic can heat up to 150 degrees. This temperature is much higher than the recommended 110 degrees mark, up to 20 degrees higher than outdoors.

All this warm air in the attic will result in excessive condensation on AC ducts. You can manage this temperature better by properly insulating your attic since that would also help keep your house cool in warmer months.

How To Stop Condensation on Air Ducts?          

To stop ductwork sweating, you will need to control several things around your house and make important changes.

1. Reduce the Humidity Level

Lowering the overall humidity levels in your home will can help reduce ductwork sweating. If you live in an area with naturally high humidity, investing in a dehumidifier will go a long way. You can connect it with a smart AC controller to automate and maintain the moisture level in your home at a safe and comfortable level.

2. Properly Maintain Ducts

Like air filters, air conditioner ducts can also get clogged up with dust, debris, pet dander, or even dead insects. Blocked ductwork can lead to retracted airflow, which, as we discussed above, can lead to condensation on AC ducts. While you can clean and replace air filters, you can’t DIY duct maintenance. It’s always advisable to hire a professional HVAC contractor since they have the specialized equipment that the task requires.

3. Add Insulation to Metal Ducts

An HVAC technician insulating the the metal ducts

You don’t have to worry about insulation with a flexible duct system since they have insulation built around them by default. You can hand seal any exposed connection points to stop ductwork sweating.

However, with older metal ductwork, the only solution is adding insulation. It’s a fairly simple task and won’t cost over $400 if you’re nifty with DIY home repairs. Also, pay attention to any gaps in the ductwork or the walls through which air can pass. Seal these gaps with aluminum foil tape or caulk them.

Attic insulation is also important if you have your AC ductwork up there.

4. Keep Your Air Filters Clean

A clean HVAC filter can cut back your energy costs by up to 15%. But that isn’t the only benefit. Dirty air filters restrict airflow, which can impact your air conditioner’s cooling and dehumidifying abilities. This leads to high humidity in your home, which can, in turn, cause condensation on air ducts. Depending on the type of air filter you use and where you live, you might have to clean or replace the filter every month, every few months, or every year.

Take Away

Learning how to stop condensation on air ducts can seem daunting at first. But understanding the primary causes behind ductwork sweating can help make the task much simpler. High humidity levels, poor insulation, dirty air filters, and blocked ductwork can cause condensation on AC ducts. You can counter these issues by maintaining your ductwork, investing in a dehumidifier, and adding insulation around your AC ducts. Call us at Professional AC & Heating for your HVAC needs.