Do You Need to Replace Ductwork When Replacing Your AC?

If you’re about to replace your home’s air conditioning system, you may wonder whether you should replace your ductwork. Most ductwork lasts between 10 and 15 years, which is about as long as ACs last. So, if your AC and ductwork are both toward the end of their life spans—or several years older—it’s often worth replacing your ductwork with your AC. 

However, you don’t always need to replace your ductwork when you refresh your AC. How can you tell which camp you and your shiny, new HVAC system will be in? Here’s how to determine if you need to replace ductwork when replacing your AC. 

What Is Ductwork?

Your ductwork is, put simply, your system of ducts—the tubes, often metal, that allow air from your HVAC system to circulate through your home and get into every room. Without ducts, your air conditioner would be useless because the chilled or heated air wouldn’t go anywhere (unless, of course, you have a ductless AC unit, like a window unit or some types of mini splits).

When to Replace Your Ductwork

Here are some scenarios in which you may need to have your ductwork replaced alongside your AC unit.

Your Ductwork Isn’t the Right Size for Your New HVAC System

In a similar vein, your ductwork may simply not be the right size to fit your new HVAC system or air conditioning unit, in which case your unit’s performance may be compromised, and your energy bills might go way up. Under these circumstances, it can actually be more cost-effective in the long run to have your ductwork replaced.

Your Ductwork Is Damaged or Corroded

Even very sturdy ductwork doesn’t last forever, and if your ductwork is damaged or corroded, having your AC replaced may be a perfect opportunity to replace your ductwork, as well. Some signs that your ductwork may be damaged include:

• Higher-than-average energy bills

• Strange AC unit noises or odors

• Uneven heating or cooling throughout your home

• Excessive dust in your home

• Noticeable debris or dirt around your air vents

These signs could indicate leaky ductwork that might allow mold and bacteria to grow or even become infested with pests. Long story short: If your ductwork has gone bad, you’ll definitely want to replace it (even if you’re not getting a new AC unit).

Your Current Ductwork Is Designed Inefficiently

Uneven heating and cooling can indicate a problem with your ductwork or be reflective of an outdated design or poor maintenance. 

For example, maybe your home has an addition that’s newer than the rest of the home, and the ductwork to that addition was retrofitted after the fact. If the installation wasn’t done properly, the addition might not get the same kind of heating or cooling effect as other parts of your home, a problem that may require a wholesale redesign of your ductwork (or, at the very least, some repairs).

Similarly, previous patch jobs on existing dated ductwork systems can mean cracked, aged, or leaky ductwork that doesn’t properly heat or cool your home. Inefficient or outdated ductwork can make your HVAC work harder and still not heat or cool your home properly.

Repairing vs. Replacing Ductwork

If the idea of having your entire ductwork system replaced is making you sweat, rest easy: You may be able to simply have portions of your ductwork repaired instead. If your ducts aren’t very old or deteriorated, your local duct installer may be able to simply repair any problem portions and connect your new AC unit directly to your older duct system. 

How Much Does It Cost to Repair or Replace Ductwork?

Keep in mind that your ducts will need replacing at some point, so it may make sense to do everything at once. The cost to replace ductwork can range between $455 and $2,180 while repairing ductwork costs between $130 and $2,000, on average. Prices will depend on the size of your home and the extent of the replacement or repair. 

Signs of Damaged Ductwork

There are tell-tale signs that ductwork is in dire need of some TLC. Here are the biggest red flags: 

• Poor airflow: If the system struggles to send air throughout the home, a damaged duct could be the problem. 

• Strange noises: A damaged duct may sound like rattling, shaking, clamoring, or dinging.

• Inconsistent temperatures: Poor airflow caused by damage also translates to inconsistent temperatures with plenty of dead zones. 

• Higher energy bills: When your ducts are damaged, your system has to work harder, increasing energy costs. 

• Foul odors: A damaged duct is often exposed to moisture, leading to mold and mildew buildup that causes an odor.