Air Quality & Ventilation in Hillsborough — Same-Day Service, Done Right the First Time

Fast, Reliable Air Quality & Ventilation Across Hillsborough

Air quality and ventilation work in Hillsborough isn’t like working anywhere else on the Peninsula. Every home here is a custom estate, many expanded from original 1940s–1960s footprints into 10,000+ square foot residences with lath-and-plaster walls, finished attics, and piecemeal additions that make standard HVAC approaches fail. We’re Stonegate Heating & Air California, and we’ve spent 16 years solving exactly these problems — owner Jason Trent on-site as Field Supervisor, 499 verified reviews at 4.7 stars, and factory-trained experience across nine brands including Carrier, Trane, and Lennox. Hillsborough sits just east of the Crystal Springs ridgeline, which blocks direct coastal fog and creates warmer, sunnier conditions than Burlingame or Millbrae — but the real challenge is thermal comfort across enormous floor plans where a south-facing great room can run 5°F hotter than a shaded north wing. We understand the permit strictness here, the routing headaches of older construction, and the precision that $50,000 system replacements demand. Call (855) 467-1888 for a free estimate.

Call (855) 467-1888

Why Stonegate Heating & Air California Is Hillsborough’s Preferred Air Quality & Ventilation Company

Our reputation in Hillsborough was built one estate home at a time. We’ve learned that homeowners here research deeply before calling — they’ve dealt with franchise chains that send whichever tech is available, and they want a contractor with a real name, a proven track record, and someone accountable on-site. That’s exactly what we deliver. Jason Trent doesn’t just own Stonegate; he serves as Field Supervisor, meaning company leadership is physically present on job sites, not managing from a back office.

Nearly 500 customer reviews averaging 4.7 stars reflect consistent, repeatable results across hundreds of real jobs — not a handful of cherry-picked testimonials. For Hillsborough specifically, our response times match what you’d expect for a local specialist who knows the area: we understand the difference between a home off El Camino Real and one tucked up near Skyline Boulevard, and we plan accordingly.

What separates us in this market is our fluency with multi-zone retrofits. Neighboring Burlingame and San Mateo have apartment complexes, commercial strips, and tract housing. Hillsborough has none of that. Every job is a large-lot custom home with unique duct-routing challenges, and our Air Quality & Ventilation team has developed specific methods for lath-and-plaster walls and finished attics that technicians from generic shops simply haven’t encountered.

Our Air Quality & Ventilation Services in Hillsborough

ERV & HRV System Installation

Hillsborough’s estate homes lose enormous amounts of conditioned air through ventilation, especially in 5,000–15,000 sq ft properties with older envelopes. An Energy Recovery Ventilator (ERV) or Heat Recovery Ventilator (HRV) exchanges stale indoor air with fresh outdoor air while transferring heat and moisture between the two streams. In Hillsborough’s specific climate — warmer and sunnier than coastal Peninsula cities but rarely exceeding the low 80s°F — an ERV typically makes more sense than an HRV, as it handles both temperature and humidity transfer. We installed a multi-zone ERV system in a 12,000 sq ft estate near Crystal Springs Road, where the lath-and-plaster walls and finished attic required custom duct routing to balance humidity across the south-facing great room and north wing. Using a Lennox HRV, we resolved the persistent 5°F temperature differential that had plagued the homeowners for years. These systems run $4,500–$12,000 installed in Hillsborough, depending on zones and routing complexity.

Ventilation Install & Retrofit

Original Hillsborough homes were engineered for much smaller footprints. When a 1960s ranch gets expanded to 8,000 sq ft with a second story and great room addition, the existing ductwork and ventilation capacity can’t possibly serve the new load. We specialize in these retrofits, designing custom solutions that work within lath-and-plaster constraints and finished attics where standard flex-duct runs simply won’t fit. A typical whole-house ventilation retrofit in Hillsborough runs $3,500–$8,500, with complex multi-zone projects reaching $15,000+.

Air Filtration Systems

Hillsborough’s tree canopy is beautiful, but pollen loads are significant — especially from the mature oaks and redwoods that shade many north-wing bedrooms. Whole-house media filters and electronic air cleaners integrate with your existing ductwork to capture particles at the system level rather than relying on portable units that can’t possibly serve 10,000 sq ft. We size filtration to actual CFM requirements, not guesswork, because an undersized filter in a large home is barely better than none. Media filtration upgrades typically run $800–$2,200; electronic air cleaners range $1,500–$3,500.

UV Air Purifier Installation

For Hillsborough homes with finished attics where ductwork runs through warm, humid conditions, UV-C lamp systems address microbial growth on coils and in drain pans. This isn’t about marketing hype — it’s about preventing the musty odors and efficiency losses that develop when condensation sits in dark duct runs. UV systems run $600–$1,800 installed, with lamp replacement every 2–3 years.

Humidifier & Dehumidifier Install

The fog that rolls over the Crystal Springs ridgeline keeps Hillsborough more humid than inland Bay Area cities, but the south-facing great rooms in these large estates can still dry out dramatically in winter. Whole-house humidifiers and dehumidifiers solve this at the system level. We install Aprilaire, Honeywell, and Carrier units sized to actual home volume, with zoning controls that let the north wing run different humidity targets than the south. Typical range: $1,200–$3,800.

Trusted Brands We Service in Hillsborough

We maintain factory-trained or experienced capability across nine major HVAC brands: Carrier, Trane, Lennox, Goodman, Rheem, York, Daikin, Bryant, and American Standard. For Hillsborough’s high-end installations, we most commonly specify Carrier, Trane, and Lennox — not because they’re “better” in some abstract sense, but because their zoning controls, ERV/HRV integration, and smart-home compatibility match what these homes actually need. We stock common parts locally and coordinate with Bay Area distributors for same-day or next-day specialty components, which matters when a $50,000 system replacement gets flagged mid-project and you need documentation and spec sheets for permit re-submission.

Common Air Quality & Ventilation Problems We See in Hillsborough Homes

• Unpermitted equipment swaps get flagged mid-project. Hillsborough building inspectors know high-end installations and routinely stop work on equipment changes that lack proper permits. We’ve been called in to rescue projects where a previous contractor skipped this step, forcing homeowners to live without HVAC while permits get sorted retroactively.
• Lath-and-plaster walls and finished attics make duct routing extremely complex. Standard flex-duct and rectangular trunk lines that work in modern framing don’t fit through Hillsborough’s wall cavities. Without custom planning, ventilation gets undersized or blocked entirely, creating dead zones in expanded wings.
• Piecemeal home expansions create mismatched zones. A single-zone system can’t handle the thermal differential between a south-facing great room and a shaded north wing in a 10,000 sq ft home. We see this constantly: homeowners who spent $200,000 on an addition now can’t use half the house comfortably because the original 1960s system was never designed for the new load.
• Original electrical capacity can’t support modern air quality equipment. Many Hillsborough homes still run 100-amp or 150-amp service panels that were adequate for 1960s loads but can’t handle ERVs, UV systems, and multi-zone controls without upgrade. We identify this during initial assessment, not after demolition starts.

Pricing for Air Quality & Ventilation in Hillsborough, CA

We Also Serve Cities Near Hillsborough

Our Peninsula coverage includes Burlingame, Millbrae, San Mateo, and San Bruno. Each city has distinct housing stock and code requirements — Burlingame’s mixed residential-commercial zoning, San Mateo’s denser neighborhoods, San Bruno’s hillside construction — but Hillsborough remains our most specialized market for large-estate air quality work. Wherever you’re located, Jason Trent supervises every project personally.

FAQs — Air Quality & Ventilation in Hillsborough