Important Notice
This article is general information about air ducts and AC replacement in Boca Raton. It is not an inspection of your home or a quote. Efficiency rules can change, so confirm the current requirements with your installer or your local building department.
Should you replace your ducts when you replace your AC?
Check them first, and replace them only if they fail. Ducts often outlast the AC, but leaky, wrong-sized, wet, or moldy ducts make a new system work harder. ENERGY STAR estimates a typical house loses 20 to 30 percent of the air in its ducts to leaks. Ask for a duct inspection before the new unit goes in.
| What to check | Why it matters | Signs of a problem |
|---|---|---|
| Leaks and loose connections | Cooled air lost to the attic or walls, and hot humid air pulled in | Rooms that never cool, high bills, dusty attic air at the returns |
| Size and airflow | Ducts sized for the old unit may not match the new one | Whistling vents, weak airflow, noisy returns |
| Insulation | Wet or damaged insulation can't dry out and grows mold | Sweating ducts, ceiling stains near vents |
| Dust, debris, or mold inside | It goes straight into the new system | Dust blowing from vents, musty smell, visible growth |
| Physical condition | Crushed, sagging, or torn ducts restrict air | Kinked flexible ducts, gaps, tape that has peeled off |
Why does this matter more for a new AC?
Since January 1, 2023, new split-system air conditioners installed in Florida and the rest of the Southeast must meet a higher federal efficiency minimum: 14.3 SEER2 for most home-size systems (under 45,000 Btu/h), and 13.8 SEER2 for larger ones. The rule applies by installation date, so any new split AC going into a Boca Raton home today meets it.
That rating describes the equipment, not your house. A new, efficient unit still has to push air through the old ducts. If those ducts leak into a hot attic, or are too small for the new system's airflow, part of the efficiency you paid for never reaches the rooms.
What should be checked in the old ducts?
- Leaks and connections. Look at the ducts where they connect to the air handler, the plenum, and each register boot. In attics, flexible ducts can slip off their connections over the years. ENERGY STAR estimates 20 to 30 percent of the air moving through ducts in a typical house is lost to leaks, holes, and poorly connected ducts.
- Size and airflow. A new system is often a different size or moves air differently than the old one. Ask the installer to check that the existing ducts can carry the airflow the new system needs, for example by measuring the system's static pressure.
- Insulation. Ducts in a hot Florida attic need intact insulation to keep cool air cool and stop condensation on the outside of the duct. EPA says wet or moldy duct insulation, or fiberglass duct material, cannot be effectively cleaned and should be removed and replaced.
- What's inside. EPA lists three situations where duct cleaning may be needed: substantial visible mold growth inside the ducts or system, insects or rodents in the ducts, and ducts clogged with dust and debris or releasing it from the vents.
- Physical condition. Look for flexible ducts that are crushed, kinked, sagging, or torn, and for tape that has peeled away from joints.
Clean, seal, or replace?
The inspection decides. Each finding points to a different fix:
| Finding | Usual fix |
|---|---|
| Ducts are sound, but leak at joints and connections | Seal the joints and reconnect loose ducts |
| Ducts are sound, but dust or debris built up inside | Clean the ducts |
| Insulation is wet, moldy, or falling apart | Replace those sections |
| Visible mold growth inside the ducts | Fix the moisture source, then clean or replace, depending on the duct material |
| Ducts are too small for the new system's airflow | Resize or add ducts, or reconsider the equipment size |
| Flexible ducts crushed, torn, or badly sagging | Replace or re-hang those runs |
Replacing every duct is rarely the only option. Often a few sections need replacing, the rest need sealing, and some homes need cleaning.
When is the best time to deal with the ducts?
Before the new unit goes in, or during the same visit.
Once the new system is running, it pulls air back through the old return ducts and across a brand-new coil. Any dust, debris, or growth in those ducts goes straight to the new equipment. Fixing the ducts first also means the installer can test the system with the ducts it will actually use.
What should you ask the AC installer?
- Will you inspect the existing ducts before quoting, and show me photos?
- Will you check that the ducts can handle the new system's airflow, for example by measuring static pressure?
- Will you check for and seal leaks at the air handler, plenum, and registers?
- Is any duct work included in the quote, or priced separately?
- If the ducts need cleaning, sealing, or replacement, what exactly will be done, and what does it cost in writing?
An installer who quotes a new system without looking at the ducts is quoting half the job.
What makes Boca Raton homes different?
Attic ducts in a hot climate. In many single-family homes in Boca Raton, ducts run through the attic, where summer temperatures are far higher than outdoors. Leaks and thin insulation there cost more than in a cooler place, and condensation on the outside of cold ducts is common when insulation is damaged.
AC that runs most of the year. In Palm Beach County the AC runs for most of the year, so duct problems cost something almost every month, not just in summer.
Condos and closets. In many condos, the air handler sits in a closet and the duct runs are short. Leaks at the air handler cabinet and the return are the main things to check there.
Seasonal homes. Many homes sit closed through the summer. A replacement after a season of humidity is a good time to check the ducts for moisture and growth.
Frequently Asked Questions
Do I need new ductwork with a new AC?
Not always. Many homes can keep their ducts if an inspection shows they are sound, sized for the new system, and free of wet insulation and mold. Leaky joints can be sealed and dirty ducts can be cleaned.
How do I know if my ducts can handle a new AC?
Ask the installer to check the system's airflow, for example by measuring static pressure, and to compare the duct sizes to what the new system needs. Whistling vents and weak airflow are common signs of ducts that are too small.
Can old ducts reduce the efficiency of a new AC?
Yes. A new unit's efficiency rating describes the equipment. If the ducts leak into a hot attic or restrict airflow, part of that efficiency never reaches the rooms. ENERGY STAR estimates a typical house loses 20 to 30 percent of duct air to leaks.
Should I clean my ducts before installing a new AC?
If an inspection shows dust, debris, or growth inside them, yes, before or during the installation. Otherwise the new system pulls that material back across its new coil. If the ducts are clean, cleaning them adds nothing.
What is the minimum efficiency for a new AC in Florida?
Since January 1, 2023, new split-system air conditioners installed in the Southeast, including Florida, must be at least 14.3 SEER2 for systems under 45,000 Btu/h and 13.8 SEER2 for larger systems.
Can wet duct insulation be dried out and reused?
EPA says wet or moldy duct insulation, or fiberglass duct material, cannot be effectively cleaned and should be removed and replaced. Find and fix the source of the water first.
Final Thoughts
A new AC in Boca Raton is a large purchase, and the ducts decide how much of its efficiency actually reaches your rooms. Have the ducts inspected before the new unit goes in, and fix what the inspection finds in the same project.
Sources and Authoritative References
- ENERGY STAR, Duct Sealing
- AHRI, Residential Central Air Conditioners (2023 regional standards)
- U.S. Department of Energy, 2023 Central Air Conditioner Standards FAQ
- City of Coral Springs, New Energy Efficiency Standards
- U.S. Environmental Protection Agency, Should You Have the Air Ducts in Your Home Cleaned?