Whole-system duct and dryer vent check with before-and-after photos - you see exactly what came out of your vents
That "$99 whole-house special" is a bait ad - the real number appears once they are in your hallway, or the "clean" is a shop-vac at the register. We photograph the inside of your ducts before and after instead.
Aprilaire Duct Repair & Sealing in Rockville: What to Know First
We provide independent Aprilaire duct repair and sealing in Rockville with written pricing delivered before any work starts, typically completing standard repairs in a single visit. Most Aprilaire systems we see in Rockville homes fall between $380 and $740 for full duct sealing with mastic and register repair, with flex duct replacement running higher depending on attic access. As an independent Aprilaire service provider, we are not affiliated with or authorized by the manufacturer, but we stock OEM and quality aftermarket parts specific to Aprilaire’s current and discontinued lines. This page is for homeowners in Rockville who own an Aprilaire air cleaner, humidifier, or ventilation system and have noticed uneven temperatures, rising energy bills, or visible gaps at duct connections. Call (240) 255-4519 for a free estimate with written pricing.
How Aprilaire Products Fail - and How We Fix Them
- Aprilaire 5000 Series Electronic Air Cleaners: The 6-inch media cabinet is built into the return plenum, the large metal box that distributes air back to your furnace. When the cabinet seals degrade, unfiltered air bypasses the media entirely. We see this constantly in Rockville’s older colonials near Woodley Gardens where the original gaskets have hardened after 15-plus years. We replace the cabinet seals with OEM-grade closed-cell foam and reseal the plenum joint with mastic sealant, a thick paste that hardens to an airtight finish.
- Aprilaire 600/700 Humidifier Duct Collars: The 6-inch round duct collar that feeds humidified air into your supply trunk is a press-fit connection with a single screw. Thermal cycling in Rockville’s freeze-thaw winters loosens this joint until moist air leaks into the attic or basement. On a job near Rockville Town Center last February, the camera showed a 2-inch gap where the collar had backed out completely, dumping humidity into an unfinished basement. We secure the collar with sheet-metal screws and seal the perimeter with high-temperature mastic rated for humidifier discharge.
- Aprilaire 8140/8145 Ventilators: These whole-house ventilators use flex duct runs, the insulated flexible tubing that connects the unit to exterior hoods. The inner liner tears where it bends sharply at the unit cabinet, especially in tight attic spaces common to Rockville’s 1960s split-levels. We cut back to sound liner, install a metal elbow to eliminate the stress point, and reconnect with a UL181-rated flex duct sleeve, not duct tape, which fails within two years in Maryland humidity.
- Aprilaire 1820/1830 Dehumidifiers: The supply and return plenums on these crawlspace units are often field-fabricated by the original installer, not factory parts. Poor seams at the plenum corners create negative-pressure leaks that draw in crawlspace air, defeating the dehumidifier’s purpose. We rebuild these plenums with galvanized sheet metal, drive-cleat corners, and mastic on every seam, then pressure-test to verify the cabinet runs at design static pressure, the resistance the fan is engineered to overcome.
- Aprilaire Zoned Comfort Control Dampers: The motorized dampers in Aprilaire zoning systems sit directly in metal ductwork. When a damper actuator fails, homeowners often hear a loud clicking as the motor strains against a seized blade. The real damage is the air leaking around the damper shaft seal while the system tries to compensate. We replace the actuator with an OEM-compatible unit and reseal the shaft penetration with a neoprene grommet and mastic, restoring zone isolation so the system doesn’t over-condition one area while starving another.
Our Aprilaire Duct Repair & Sealing Process

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Inspection with documented photo record. We remove the access panel and run a borescope camera through every duct run, the individual branch lines feeding each room. You see the images on a tablet before we quote a dollar. The photo comes first. The price comes after.
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Written scope and price under Haven Standard Clause 1. We deliver a single flat price for the full system, not per-vent arithmetic. No work starts until you have the written number.
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Parts decision: OEM or quality aftermarket. For current Aprilaire lines, we stock OEM gaskets, collars, and actuators. For discontinued units like the early 4400-series ventilators, we source compatible aftermarket parts and document the substitution in your job record.
- 4
Repair and seal. We replace damaged components, rebuild plenums with proper sheet-metal technique, and seal all joints with mastic. Every seam is brush-coated, not sprayed, so we can verify full coverage.
- 5
Pressure test and airflow verification. We measure static pressure before and after, and verify register airflow with a calibrated hood. The photo record, pressure readings, and airflow numbers are delivered as your standard job documentation.
- 6
Cleanup and 365-Day Done Right Promise activation. The written guarantee is included in your job record, not a separate marketing piece. If it’s not right, we make it right.
Before
AfterWhat Aprilaire Duct Repair & Sealing Costs in Rockville
| Service | Typical Range | What Moves the Price |
|---|---|---|
| Register seal and collar repair (1-2 points) | $280 - $420 | Attic access, plaster repair needed |
| Full duct sealing with mastic (single system) | $380 - $740 | System size, number of joints, accessibility |
| Flex duct replacement (per run) | $340 - $580 | Length, insulation R-value, crawlspace vs. attic |
| Humidifier/ventilator plenum rebuild | $520 - $890 | Custom fabrication, damper integration |
| Zone damper actuator replacement with reseal | $440 - $680 | OEM vs. aftermarket, number of zones |
These are whole-system prices agreed in writing before work starts. We do not quote per-vent rates or advertise teaser figures that change once the truck arrives. Factors that increase cost: buried flex duct in finished basements, asbestos-wrapped original duct requiring abatement coordination, and multi-zone systems with failed dampers in series. Call (240) 255-4519 for an exact quote - estimates are free, and we provide a Free Second Opinion on any competitor’s written estimate.
Why Rockville Homeowners Call CleanRun Air Duct Cleaning Rockville for Aprilaire Work

We’ve been running jobs across Rockville since 2013, including plenty of work in the older split-levels near Congressional Plaza where the original flex duct tends to show its age in ways that aren’t obvious until you pull the register cover. Tomas Reyes and our crew know Aprilaire’s product evolution because we’ve repaired systems from the discontinued 4400 ventilator line through current 600M humidifiers still under factory warranty. Our equipment roster includes Rotobrush, Nikro, Abatement Technologies, Honeywell, Aprilaire, and Guardsman - professional-grade tools you can look up before agreeing to a price. We also service Lennox, Trane, and Carrier systems, so when an Aprilaire component interfaces with another brand’s equipment, we don’t guess at the integration. Every technician is background-checked and uniformed under Haven Standard Clause 3: Verified Crews. The 365-Day Done Right Promise is backed in writing on every job, and the documented photo record is included as standard, not an upsell.
FAQs
No, independent repair of the ductwork surrounding your Aprilaire unit does not void the manufacturer’s product warranty, provided the unit itself is not modified. We document our work with photos to prove no factory components were altered if a future warranty claim arises. For Aprilaire units still under factory warranty, we use OEM-compatible parts and note serial numbers in your job record. Call (240) 255-4519 if you need help determining your warranty status.
The unit is likely at fault if the display shows error codes, the fan won’t start, or water leaks from a humidifier. The ductwork is likely at fault if you have uneven room temperatures, whistling at registers, or visible gaps at plenum connections. We diagnose both during our inspection and show you the camera footage so you can see where the failure is. Call (240) 255-4519 for a free inspection with written findings.
Repair is the better value when the duct damage is localized to a few joints or one flex run, and the Aprilaire unit itself is functioning. Replacement makes sense when the ductwork is original galvanized steel with widespread corrosion, or when you’re already upgrading to a new HVAC system. We give you both options in writing with prices for each, not a steer toward the more expensive choice. Call (240) 255-4519 to review your specific situation.
Standard sealing and register repair is completed in four to six hours. Flex duct replacement or plenum rebuilds may extend to a full day depending on attic or crawlspace access. We schedule the work at your convenience and do not rush jobs to hit a dispatch quota. Call (240) 255-4519 to book a slot that works for your schedule.
The $79 coupon model relies on arriving at your home and finding “additional problems” that multiply the final invoice. Our price is the price, written before work starts under Haven Standard Clause 1. We also deliver a documented photo record of every duct run so you can verify the work was actually performed, not just vacuum noise. The difference is accountability you can hold in your hand. Call (240) 255-4519 for a written quote you can compare directly.
Ready for a written estimate on your Aprilaire duct repair and sealing in Rockville? Call (240) 255-4519. A live person answers, and we’ll schedule a free inspection with pricing delivered in writing before any work begins. Bring a competitor’s written estimate and we’ll provide a Free Second Opinion at no cost.
Written by Tomas Reyes, Owner, CleanRun Air Duct Cleaning Rockville at CleanRun Air Duct Cleaning Rockville, serving Rockville and nearby areas.




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