--- title: "Duct Repair and Sealing in Boca Raton, FL | Direct Cooling" description: "Leaky attic ducts waste the cooling you pay for. Direct Cooling finds, seals and replaces ductwork in Boca Raton homes and explains what Florida code requires." canonical_url: "https://www.directcoolingfl.com/ductwork" last_updated: "2026-10-06" language: "en" --- Ductwork repair in Boca Raton # Ductwork Repair in Boca Raton: Find the Leak Before You Buy a New AC If some rooms never cool and the bill keeps climbing while the AC itself checks out, the ducts are the first place to look. Direct Cooling repairs, seals and replaces ductwork across Boca Raton and nearby cities, and we inspect the duct system before recommending any new equipment. [Call or Text (561) 210-7605](tel:+15612107605) [Request a Free Estimate](https://www.directcoolingfl.com/contact) - 4.9 on Google, 360+ reviews - FL license CAC1819111 - BBB A+ accredited **Licensed and Insured** FL License CAC1819111 **4.9 Stars on Google** 360+ customer reviews **BBB A+ Accredited** Accredited since 2021 **American Standard and Rheem** Authorized dealer installs **Family-Run Since 2017** 20+ years of HVAC experience By [Direct Cooling](https://www.directcoolingfl.com/authors/direct-cooling), FL license CAC1819111Updated October 6, 202610 min readSources listed at the end Sound familiar? ## Two Rooms Never Cool and the Bill Keeps Climbing If your AC was just serviced, the refrigerant checks out, and two bedrooms still sit several degrees warmer than the rest of the house, you are describing a duct problem more often than an equipment problem. ENERGY STAR estimates that in a typical house about 20 to 30 percent of the air moving through the duct system is lost to leaks, holes and poorly connected ducts. That loss shows up as higher bills and rooms that never feel right, no matter where the thermostat is set. In Boca Raton the stakes are higher than the national average suggests, because most supply ducts here run through the attic. Air that escapes a supply duct is cooling you paid for, dumped into the hottest space in the house. Air pulled in through a return leak is hot, humid attic air that the AC then has to cool and dry all over again. ENERGY STAR lists the warning signs: high summer bills, rooms that are hard to cool, stuffy rooms that never feel comfortable, ducts located in an attic or garage, and tangled or kinked flexible duct. If two or three of those describe your home, a duct inspection is a better first step than a quote for a bigger system. A larger AC pushed through the same leaky ducts loses the same share of its air. Florida research ## What Florida Duct Studies Actually Measured Most duct advice online is generic. These numbers come from Florida Solar Energy Center (FSEC) field studies in Florida homes, which is why we lean on them when we explain a duct problem to a homeowner. Findings from FSEC duct and air handler field research in Florida homes | What was measured | Finding | Why it matters in your house | | --- | --- | --- | | Return leaks from a hot attic | A return leak pulling 15% of its air from a 120°F attic at an 80°F dew point can cut cooling capacity and efficiency by about 50% (FSEC, ASHRAE Journal, 2008) | A modest leak at the return can make a correctly sized AC feel undersized on summer afternoons | | Return leaks in 91 Florida homes | Return leaks averaged 10.0% of air handler flow; 60% of homes had at least 5% and 30% had more than 10% (FSEC, 1990) | Return leaks were common, not rare, in ordinary Florida houses | | Air handler running vs off | House infiltration was four times higher with the air handler on (0.93 vs 0.21 air changes per hour) | Leaky ducts pull outside air into the house every time the fan runs | | Where the biggest return leaks were | Most often the return plenum, the box the air handler sits on; leaks there commonly ran 5% to 25% of airflow and were measured as high as 55% | The air handler closet deserves as much attention as the attic | | After duct repair in 24 homes | Return leaks fell from 16.7% to 4.5% and measured AC energy use dropped 18.0% on average (range 3.5% to 44.6%) | Results vary with how much of the leakage can actually be reached and sealed | | Air handler cabinets in 69 new homes | Installers had sealed only an area-weighted 16% of the cabinet penetrations they could have sealed; missing refrigerant line gaskets were about half the cabinet leakage in non-gas units | Even a new system can leak at the air handler if the install skipped the seals | The 91-home and 24-home figures are from an FSEC study published in 1990 in central Florida; the 69-home air handler data and the 50% return leak figure are from Cummings and Withers, ASHRAE Journal, January 2008. ![New insulated supply duct and register box in an open ceiling during a remodel](https://www.directcoolingfl.com/img/work/direct-cooling-supply-duct-open-ceiling-remodel.webp) [Ductwork](https://www.directcoolingfl.com/ductwork)New supply duct in an open ceiling The return side ## Why Return Leaks Hurt Most in a South Florida Attic A return leak does more damage in our climate than a supply leak of the same size. The return side is under suction, so any gap pulls in whatever surrounds it. In an attic that can reach 120°F on a summer afternoon, that air arrives hot and loaded with moisture, and the coil has to remove both the heat and the water before it can cool your living space. FSEC researchers calculated that a 30% return leak can completely overwhelm a system's capacity, which is when the house temperature starts climbing even though the AC never shuts off. Return leaks also carry dirt. When filters sit at the return grille in the hallway, air that leaks into the return duct downstream of that grille never passes through a filter. FSEC found this lets dust collect inside ductwork, on the cooling coil and on the blower wheel, which lowers performance and raises the odds of air quality problems. If your coil gets dirty fast even though you change filters on schedule, a return leak is a strong suspect. The third problem is condensation. FSEC described how a leak in the air handler cabinet between the coil and the blower can draw humid air into an airstream that has just been cooled to about 55°F. With summer dew points in the mid-70s, that air can form a fog that wets the blower section and the supply ducts. Wet insulation does not insulate, and EPA notes that wet or moldy duct insulation cannot be effectively cleaned and should be removed and replaced. That is why our duct inspections start at the air handler, not just in the attic. The return plenum, the filter door, the refrigerant line and wiring penetrations, and the connection between the cabinet and the platform are some of the most common leak points FSEC documented in Florida homes. Homeowner checks ## What You Can Check Without Climbing Into the Attic Florida attics get dangerously hot in summer, so keep your own checks to the living space and the air handler closet, and leave the attic to us. Each of these gives us useful clues before we arrive. ### Safe to do yourself 1. **Map the weak rooms** Walk the house with the AC running and note which rooms have weak airflow or run warm. That room map often points straight to a crushed or disconnected run. 2. **Keep registers open and clear** The U.S. Department of Energy notes that discomfort can often be traced to blocked registers, stuck dampers, or disconnected or damaged ducts. 3. **Do not close vents to save energy** In a Lawrence Berkeley National Laboratory study, closing registers increased energy use because duct leakage rose, and closing more than 60% of them risked frozen cooling coils. 4. **Look at the filter door** A missing or ajar filter access door on the air handler is a direct leak. FSEC measured one missing door leaking about nine times the average cabinet leakage in its 69-home sample. 5. **Watch for dust streaks** Dark lines around ceiling registers can point to air leaking around the boot where the duct meets the ceiling. ### Stop and call a pro - **Sealing joints in the attic** Done with mastic or metal tape. ENERGY STAR says never use duct tape because it does not last. - **Disconnected, crushed or sagging flex duct** Reconnecting, supporting and insulating runs properly in a hot attic is a professional job. - **Wet or moldy duct insulation** EPA says it cannot be effectively cleaned and should be removed and replaced. ![American Standard air handler on a raised stand in a garage with insulated refrigerant lines](https://www.directcoolingfl.com/img/work/direct-cooling-american-standard-air-handler-garage.webp) [Installation](https://www.directcoolingfl.com/ac-installation)American Standard air handler on a raised stand Our process ## How We Diagnose a Duct Problem Diagnose first, sell second applies to ducts as much as to AC repair. This is the order we work in, so the fix matches the leak instead of the sales sheet. ### Start with your room map Which rooms run warm, when it happens, and whether the bill jumped recently. Patterns tell us whether to suspect one branch or the whole system. ### Measure at the registers Airflow and supply temperature room by room, compared with the rooms that cool well, plus the temperature split across the coil. ### Inspect the air handler and return Cabinet panels, filter door, line set and wire penetrations, and the return plenum or platform, where FSEC found the largest return leaks. ### Trace the attic runs Connections at the plenum and each takeoff, boots at the ceiling, crushed or kinked flex, missing insulation and signs of condensation. ### Show you the findings What we found, where, and which fix it calls for: targeted repair, sealing, or replacement. You decide before any work starts. ### Test new work to code When a duct system is replaced or extended, the Florida energy code requires it to be sealed and tested, and we handle that. Choosing the fix ## Repair, Seal or Replace: Which Duct Fix Fits Most duct problems do not need a whole new system. The right fix depends on how widespread the damage is and what condition the materials are in. Duct repair, sealing and replacement compared | Fix | When it fits | What it involves | | --- | --- | --- | | Targeted repair | One or two rooms are weak; a run is disconnected, crushed or torn | Reconnecting and strapping the run, replacing the damaged section, sealing and insulating the joint | | Sealing | Ducts are sound but leak at joints, boots, takeoffs or the air handler | Mastic or metal tape at every reachable joint, sealing boots to the ceiling and closing cabinet and return plenum leaks | | Return plenum rebuild | The box under the air handler leaks or the platform is open to wall cavities | Rebuilding or sealing the plenum so the return draws only from the house; Florida code does not allow building framing cavities to be used as ducts | | Full replacement | Insulation is wet, moldy or deteriorated throughout, or the layout never delivered enough air | New duct system sized for the house, insulated to code and sealed and tested before it is signed off | We focus on duct repair, sealing and replacement rather than duct cleaning. Florida code ## What the 2023 Florida Energy Code Requires for Ducts These are the duct rules in the 2023 Florida Building Code, Energy Conservation (Residential). Palm Beach County sits in Climate Zone 1A. Key residential duct requirements in the 2023 Florida energy code | Requirement | What the code says | | --- | --- | | Attic duct insulation (R403.3.1) | R-8 for supply and return ducts 3 inches in diameter and larger in attics; R-6 for smaller ones | | Sealing (R403.3.2) | Ducts, air handlers, filter boxes and building cavities that carry air must be sealed and tested to be substantially leak free | | Sealed air handler (R403.3.2.1) | Air handlers must be rated by the manufacturer for leakage of no more than 2% of design airflow when tested to ASHRAE 193 | | Leakage limit (R403.3.4) | Tested at 25 Pa: no more than 4 cubic feet per minute per 100 square feet of conditioned floor area post construction, or at rough-in with the air handler installed | | Building cavities (R403.3.5) | Building framing cavities shall not be used as ducts or plenums | | Alterations (R503.1.2) | New duct systems in an alteration must meet the same sealing and testing rules; extensions with less than 40 linear feet in unconditioned space are exempt from testing | | Reused ducts (R501.7) | Existing ducts may stay in place on an equipment replacement when bringing them to code would require replacing them | Because reused ducts are not brought up to current code when the AC is replaced, a new high-efficiency system can end up connected to old, leaky ductwork. We inspect the ducts as part of every replacement quote for that reason. Local homes ## How South Florida Construction Shapes Duct Problems The way homes here are built decides where ducts run and where they fail. ### Slab, block and an attic full of ducts In FSEC's Florida sample, more than 90% of homes were on concrete slabs and more than 80% had block walls, so supply ducts ran through the attic, the worst place for a leak in summer. ### Older homes leak more FSEC found house airtightness tracked age: homes under 10 years old tested around 8 air changes per hour at 50 Pa, while homes over 20 years old averaged about 17. ### The air handler closet Return plenums built into closets and utility rooms are often joined into the surrounding walls. When they are not airtight, they can draw air down the wall cavities from the attic. ### Garage air handlers FSEC cautions that air handlers and return ducts in an attached garage can carry car exhaust and fuel vapors into the house, so those returns need to be sealed tight. ### Humid air on cold metal Summer dew points around [West Palm Beach](https://www.directcoolingfl.com/service-area/west-palm-beach) average roughly 72 to 74°F (NOAA normals), so any uninsulated or poorly sealed duct section can sweat and drip onto ceilings. Replacing the AC? ## Check the Ducts Before You Replace the AC If you are pricing a new system, the ducts deserve a look first. Florida's energy code lets existing ducts stay in place when the equipment is replaced, so nothing forces anyone to test them. A new, higher-efficiency system connected to a duct system that loses a quarter of its air will not deliver the comfort or the savings on the label. The same research that shows how much leaks cost also shows what fixing them can do. In the FSEC study of 24 monitored Florida homes, repairing ducts cut measured AC energy use by 18% on average. The home with the biggest savings had a 26.1% return leak drawn almost entirely from the attic; its owner had the thermostat at 79°F while the house often reached 82°F or more on afternoons. The home with the smallest savings had its worst leaks in a part of the attic that could not be reached. Those two homes are a good reminder that results depend on access and on how bad the leaks were to begin with. When we quote an [AC replacement](https://www.directcoolingfl.com/ac-replacement), we tell you what condition the ducts are in and whether they should be repaired, sealed or replaced along with the equipment. If only one or two rooms are the problem and the rest of the system is sound, a [ductless mini split](https://www.directcoolingfl.com/mini-splits) for those rooms is another option we can walk you through. And if dust or musty air is part of the complaint, our [indoor air quality](https://www.directcoolingfl.com/indoor-air-quality) page explains how return leaks and moisture tie together. **Licensed, local and diagnosis first** Direct Cooling is a family-run Boca Raton contractor founded in 2017 by Francisco "Frank" Rey, Florida certified air conditioning contractor CAC1819111. Every technician is trained by Frank to diagnose first and sell second. Call or text [(561) 210-7605](tel:+15612107605) to describe which rooms are struggling. Dispatch 24/7 [(561) 210-7605](tel:+15612107605) Call or text. A real person answers and gets a technician moving. [Call](tel:+15612107605) [Text](sms:+15612107605) [Book online](https://book.housecallpro.com/book/Direct-Cooling/96b950a03c9d4d6db24741db866e2a4a?v2=true&lead_source=website) ![Direct Cooling technicians running insulated flex duct through open ceiling framing](https://www.directcoolingfl.com/img/work/direct-cooling-flex-duct-install-new-construction.webp) [Ductwork](https://www.directcoolingfl.com/ductwork)Running insulated flex duct in a new build Related - [AC Replacement](https://www.directcoolingfl.com/ac-replacement) - [Mini Splits and Ductless](https://www.directcoolingfl.com/mini-splits) - [Indoor Air Quality](https://www.directcoolingfl.com/indoor-air-quality) - [Membership plan](https://www.directcoolingfl.com/membership) - [Areas we serve](https://www.directcoolingfl.com/service-area) Where we work ## Where We Handle Ductwork Duct repair, sealing and replacement dispatch from our office in Boca Commerce Park in west Boca. Tap a pin for the city. Ductwork by area [West Boca Raton](https://www.directcoolingfl.com/service-area/west-boca-raton)[Delray Beach](https://www.directcoolingfl.com/service-area/delray-beach)[Boynton Beach](https://www.directcoolingfl.com/service-area/boynton-beach)[Coral Springs](https://www.directcoolingfl.com/service-area/coral-springs)[Boca Raton](https://www.directcoolingfl.com/service-area/boca-raton)[Deerfield Beach](https://www.directcoolingfl.com/service-area/deerfield-beach)[Lake Worth](https://www.directcoolingfl.com/service-area/lake-worth)[Parkland](https://www.directcoolingfl.com/service-area/parkland)[West Palm Beach](https://www.directcoolingfl.com/service-area/west-palm-beach) FAQ ## Ductwork Questions We Hear Most **Direct Cooling** FL Certified AC Contractor CAC1819111 Dispatch 24/7 Hi, this is Direct Cooling. Tap a question below for a straight answer. Tap a question to ask Not on the list? [Browse every answered question](https://www.directcoolingfl.com/faq), or [Text us](sms:+15612107605) [(561) 210-7605](tel:+15612107605) **How do I know if my air ducts are leaking?** The common signs ENERGY STAR lists are high summer bills, rooms that are hard to cool, stuffy rooms, ducts in the attic or garage, and kinked flex duct. Other clues are dust streaks around ceiling registers, a coil that gets dirty quickly, and a musty smell when the fan starts. A technician confirms it by measuring airflow and temperature at each register and inspecting the air handler, return plenum and attic runs. **Can I seal ducts with duct tape?** No. ENERGY STAR says never to use duct tape on ducts because it does not last. Joints should be sealed with mastic sealant or metal tape, and connections at registers should be sealed where they meet the ceiling, floor or wall. **Should I close the vents in rooms I do not use?** Usually not. A Lawrence Berkeley National Laboratory study found that closing registers increased energy use because it raised pressure and leakage in the ducts. It also found that closing more than 60% of registers can restrict airflow enough to freeze a cooling coil. If a room is unused, keep its register open and talk to us about whether the duct layout needs adjusting. **Can leaky ducts make my house more humid?** Yes. FSEC research found that duct leaks, especially on the supply side, can depressurize a house and draw humid outdoor air in through the walls and around windows. Return leaks pull hot, moist attic air into the system, which the AC then has to dry out. Sealing the ducts often helps the AC control humidity as well as temperature. **Do you offer duct cleaning?** We focus on duct repair, sealing and replacement rather than duct cleaning. EPA notes that duct cleaning has never been shown to prevent health problems, and that wet or moldy duct insulation cannot be effectively cleaned and should be replaced. If we find contaminated or deteriorated duct sections, we will tell you and quote the repair or replacement. **Will new ducts be tested?** Yes. Under the 2023 Florida energy code, new duct systems, including new ducts installed as part of an alteration, must be sealed and tested for leakage at 25 pascals. Short extensions with less than 40 linear feet in unconditioned space are exempt from testing. We handle the testing requirement when we replace a duct system. ## Hot Rooms or a Bill That Keeps Climbing? Tell us which rooms struggle and when. We will check the ducts and the air handler before recommending any new equipment. [(561) 210-7605](tel:+15612107605) [Book Online](https://book.housecallpro.com/book/Direct-Cooling/96b950a03c9d4d6db24741db866e2a4a?v2=true&lead_source=website) Related ## Related Services [AC Replacement An honest repair-or-replace answer, then a clean change-out when replacement wins. Learn more](https://www.directcoolingfl.com/ac-replacement)[Mini Splits and Ductless Ductless cooling for additions, garages and rooms the central system never reaches. Learn more](https://www.directcoolingfl.com/mini-splits)[Indoor Air Quality Filtration, UV light and humidity control for cleaner, drier air at home. Learn more](https://www.directcoolingfl.com/indoor-air-quality) ## Sources · page reviewed 2026-10-06 1. [ENERGY STAR, Duct sealing](https://www.energystar.gov/saveathome/heating-cooling/duct-sealing), read 2026-10-06 2. [Cummings and Withers, FSEC, Problems related to air handler leakage (ASHRAE Journal, January 2008)](https://publications.energyresearch.ucf.edu//wp-content/uploads/2018/06/FSEC-GP-335-08.pdf), read 2026-10-06 3. [Cummings et al., FSEC, Impacts of duct leakage in Florida homes (ACEEE 1990, FSEC-PF-217-96)](https://publications.energyresearch.ucf.edu//wp-content/uploads/2018/06/FSEC-PF-217-96.pdf), read 2026-10-06 4. [2023 Florida Building Code, Energy Conservation, Chapter 4 (R403.3)](https://up.codes/viewer/florida/fl-energy-conservation-code-2023/chapter/RE_4/re-residential-energy-efficiency), read 2026-10-06 5. [2023 Florida Building Code, Energy Conservation, Chapter 5 (existing buildings)](https://up.codes/viewer/florida/fl-energy-conservation-code-2023/chapter/RE_5/re-existing-buildings), read 2026-10-06 6. [U.S. DOE, Energy Saver Guide (2022), Air ducts](https://www.energy.gov/sites/default/files/2022-08/energy-saver-guide-2022.pdf), read 2026-10-06 7. [Lawrence Berkeley National Laboratory, Register closing effects (Walker, 2003)](https://homes.lbl.gov/publications/register-closing-effects-forced-air), read 2026-10-06 8. [EPA, Should you have the air ducts in your home cleaned?](https://www.epa.gov/indoor-air-quality-iaq/should-you-have-air-ducts-your-home-cleaned), read 2026-10-06 9. [NOAA NCEI, 1991-2020 hourly normals, West Palm Beach Intl (dew point)](https://www.ncei.noaa.gov/data/normals-hourly/1991-2020/access/USW00012844.csv), read 2026-10-06