Duct Cleaning from a Licensed Silicon Valley HVAC Contractor
NADCA ACR 2021 (Assessment, Cleaning, and Restoration of HVAC Systems) is the only published industry standard for duct cleaning in North America. It specifies inspection requirements (video borescope of trunks and branches), source removal techniques (rotary brush, air whip, skipper ball, manual contact cleaning), containment (continuous negative pressure during cleaning, minimum 0.02 in. w.c. relative to surroundings), HEPA filtration of exhaust air (99.97% at 0.3 micron), and post-cleaning verification (NADCA Vacuum Test or visual inspection of representative sections). We are NADCA-member certified and we work to the standard on every job. The pre-cleaning video and post-cleaning video are emailed to you as PDF deliverables.
The truck-mounted equipment is what separates real duct cleaning from theater. Our Hypervac PowerVac has a 16-inch flexible hose connecting to the supply or return plenum, a 5,000 CFM negative pressure source backed by a 5-stage filtration train (cyclonic separator, two-stage cartridge filter, HEPA final filter), and the entire airstream exhausts outdoors through a sealed transition. We seal every supply register and return grille, then introduce mechanical agitation tools (rotary brush for hard pipe, air whip for flex, skipper ball for trunks) at one register at a time, working from the air handler outward. Debris is captured by negative pressure and exhausted outdoors — never recirculated through the home.
The blower wheel and air handler interior are the most-skipped components in a typical duct cleaning, and they are where 70% of the system contamination actually accumulates. We pull the blower wheel on every job — yes, every job. A 10-year-old blower wheel in a Palo Alto home with the standard 1-inch fiberglass filter is typically caked with 3-6mm of compacted dust on every blade, which reduces airflow 15-30% and forces the motor to draw higher amps. We clean the wheel in a wash station outside the home, clean the blower housing, vacuum the evaporator coil from the air-handler side with a HEPA vacuum, and reinstall. Then we install a fresh MERV-13 filter (or MERV-11 if the system static pressure cannot handle MERV-13) — and we check static pressure with a Magnehelic gauge before specifying.
Wildfire smoke seasons (2017, 2018, 2020, 2021, 2024) have permanently changed Bay Area duct contamination patterns. Homes that ran HVAC during BAAQMD Spare the Air alerts pulled PM2.5 particles into the system that deposit on duct interiors and the evaporator coil. We see consistent black carbon residue on flex duct interiors in homes from Santa Rosa down through Palo Alto and into San Jose. Standard residential duct cleaning does not address smoke residue chemistry — for that we recommend an antimicrobial fogging treatment after mechanical cleaning, using EPA-registered Benefect Decon-30 or BBJ MMR (NADCA-approved products). This kills any biological component and binds residual organic compounds. Total scope adds about 90 minutes and $250-$400 to a standard cleaning.
What's Included in Every Duct Cleaning Job
- NADCA ACR 2021 standard whole-system cleaning
- Pre-cleaning video borescope of trunks and representative branches
- Truck-mounted 5,000 CFM negative pressure with HEPA-filtered exhaust
- Mechanical agitation: rotary brush (hard pipe), air whip (flex), skipper ball (trunks)
- Blower wheel pulled, washed in outdoor wash station, blower housing cleaned
- Evaporator coil HEPA vacuum from air-handler side
- Fresh MERV-13 (or MERV-11 if static dictates) filter installed at completion
- Post-cleaning video borescope showing source removal results
- Optional EPA-registered antimicrobial fogging (Benefect Decon-30) for smoke or biological contamination
Common Duct Cleaning Issues We Resolve
Visible dust accumulation around supply registers within days of cleaning
Cause: Filter bypass at filter rack, leaky return drops pulling attic dust, contaminated blower wheel never cleaned
Fix: Filter rack sealing with foam gasket, return-side leak sealing, full blower wheel pull and clean — included in NADCA-standard scope
Musty or moldy odor when AC starts
Cause: Biofilm on evaporator coil and condensate pan; common in Bay Area humidity
Fix: Coil cleaning with EPA-registered cleaner, condensate pan biocide, drain line nitrogen blow-out — $220-$420
Black soot residue inside duct interior (post wildfire season)
Cause: PM2.5 wildfire smoke pulled through system during BAAQMD Spare the Air days
Fix: Standard NADCA cleaning + Benefect Decon-30 antimicrobial fogging — $250-$400 add-on
Rodent droppings or nesting material in ductwork
Cause: Mice or rats entered through unsealed crawlspace or attic penetrations; common in older Palo Alto and Menlo Park homes
Fix: NADCA cleaning + sanitization + crawlspace seal coordination with pest control — $850-$1,800 total scope
High allergen complaints despite frequent filter changes
Cause: Filter MERV rating too low (1-inch MERV 8 misses most pollen and pet dander), bypass around filter, dirty blower wheel
Fix: Upgrade to 4-inch MERV-13 media cabinet, full system clean, filter rack seal — $450-$1,200
New construction dust throughout system
Cause: Drywall dust, sawdust, and construction debris pulled into ducts during build phase
Fix: Full NADCA cleaning recommended before move-in or after major remodel — typically $650-$1,400
Our Duct Cleaning Process
Pre-Cleaning Inspection
Video borescope of supply and return trunks, photograph blower wheel, document evaporator coil condition. We send you the video before quoting scope.
Containment Setup
Floor protection laid, supply registers sealed except the active one, return grilles sealed, truck-mounted negative pressure connected to plenum.
Source Removal
Working from air handler outward, mechanical agitation at each branch and trunk while continuous negative pressure captures debris through HEPA-filtered exhaust.
Air Handler Service
Blower wheel pulled, washed outside, housing cleaned, evap coil vacuumed from air-handler side, drain pan cleared and treated, new filter installed.
Verification & Documentation
Post-cleaning video borescope of same locations as pre-cleaning, side-by-side PDF report emailed to you within 24 hours, system tested through full cycle.
Duct Cleaning Pricing in the Bay Area
Typical duct cleaning pricing in our Silicon Valley service area runs $650 – $2 200 per system. Most jobs complete in 4-7 hours for typical 2,000-2,800 sq ft home.
Every quote is flat-rate and provided in writing before work begins. Diagnostic fees are waived when repair is approved. We never use time-and-materials billing surprise pricing.
Local Context: Duct Cleaning in Silicon Valley
Bay Area duct cleaning patterns are driven by three distinct factors. First, wildfire smoke seasons (2017 Tubbs fire, 2018 Camp fire, 2020 SCU/CZU complexes, 2021 Caldor) deposit PM2.5 and combustion residues in HVAC systems whenever the system runs during BAAQMD Spare the Air alerts — we see consistent contamination patterns from Santa Rosa south through San Jose. Second, the dry summer / wet winter Mediterranean climate produces high pollen loads March-May (oak, grass, ragweed) that overload underspec'd 1-inch MERV-8 filters and dump pollen into ductwork. Third, original 1960s-1970s flex duct in Eichler tracts (Greenmeadow, Fairmeadow, Vista Park) and ranch-style homes throughout Palo Alto, Mountain View, and Sunnyvale is reaching end of serviceable life — inner liner shedding is common and often discovered during NADCA cleaning. Coastal homes in Pacifica, Half Moon Bay, and Daly City see less wildfire impact but more salt-air biofilm in condensate-side components. We carry equipment and chemistry for all three patterns and adjust scope per the pre-cleaning video inspection findings.
HVAC Brands We Service for Duct Cleaning
Duct Cleaning FAQ
How is your duct cleaning different from the $99 specials?
The $99 specials run a residential shop-vac through one register and call it cleaning. NADCA ACR 2021 standard cleaning requires truck-mounted 5,000 CFM negative pressure, HEPA-filtered exhaust, mechanical agitation in every branch and trunk, blower wheel pull and wash, and video documentation. The equipment alone costs $48,000+ — there is no economic way to do real duct cleaning for $99. Most $99 jobs end with a $1,500-$2,500 upsell pitch for "mold remediation" the homeowner does not actually need.
How often should I have my ducts cleaned?
NADCA recommends inspection every 2 years and cleaning when warranted by visible contamination, recent renovation, post-wildfire smoke exposure, rodent intrusion, or after taking ownership of a previously-occupied home. Most Bay Area homes warrant cleaning every 5-7 years; homes with pets, smokers, or wildfire-season HVAC operation closer to 3-4 years. Cleaning on a fixed annual schedule is unnecessary and not what NADCA recommends.
Will duct cleaning improve my allergies?
Sometimes substantially, sometimes marginally — depends on what is actually contaminating the system. Cleaning removes accumulated dust, pet dander, pollen residue, and biofilm. It does not address ongoing sources (your dog, the open windows during pollen season, the unsealed attic hatch pulling allergens into the return). For meaningful allergy improvement we typically combine NADCA cleaning with MERV-13 filtration upgrade and return-side leak sealing — that combination delivers measurable PM2.5 reduction.
What is NADCA certification and why does it matter?
National Air Duct Cleaners Association is the trade body that publishes the ACR 2021 cleaning standard and certifies member companies through the Air System Cleaning Specialist (ASCS) credential. Membership requires liability insurance documentation, equipment verification, and adherence to the published standard. Non-NADCA contractors are not bound to any standard and are responsible for the bulk of duct-cleaning consumer complaints in the Bay Area.
Should I pay for the antimicrobial fogging upsell?
Only when warranted. EPA-registered antimicrobial treatment (Benefect Decon-30, BBJ MMR) is appropriate after confirmed biological contamination — visible mold growth, post-flooding, post-rodent infestation, or sometimes post-wildfire smoke exposure where chemical residue is suspected. It is NOT appropriate as a standard $400 add-on to every cleaning. Reputable contractors only offer it when the pre-cleaning inspection reveals an actual indication.
Do you clean dryer vents too?
Yes, as a separate scope. Dryer vent cleaning is critical fire safety — clogged dryer vents are a leading cause of residential fires per NFPA data. Bay Area homes with long horizontal vent runs through cabinets or walls (common in townhomes and condos in Mountain View, Sunnyvale, and Foster City) accumulate lint that gas heat alone cannot dry through. We use a rotating brush kit and shop-vac on dryer vents — typically $145-$220 standalone or $95 add-on to a duct cleaning visit.
Will you damage my ductwork?
Properly performed NADCA-standard cleaning does not damage well-installed ductwork. We do see damage occasionally on older flex duct (1970s-1980s) where the inner liner is already degraded; in those cases the cleaning reveals existing damage rather than causing it, and we document with video before proceeding. We carry $2 million liability insurance and warranty our work for any damage attributable to our process.
Do you clean ductwork in Eichler homes?
Yes. Eichler ductwork is unusual — radiant slab heating means there is no central forced-air ductwork, but many Eichlers have been retrofitted with mini-split ducted cassettes or high-velocity small-duct systems (SpacePak, Unico). The 2-inch SpacePak supply tubing requires specialized cleaning equipment with a smaller diameter brush head and lower-pressure agitation. We have the equipment for these systems — most contractors do not.