Leaky Duct Repair in Los Gatos and Saratoga: Even Comfort on Every Floor and Every System

Key Takeaways

1. Why Leaky Ducts Matter in Los Gatos and Saratoga

Los Gatos and Saratoga sit against the foothills of the Santa Cruz Mountains, inland from the coast, where summer afternoons get warm and winter nights get chilly. Many homes here are large, often built on hillside or sloped lots, with additions and remodels layered on over the years.

That means long duct runs, ducts in attics and crawl spaces, and often more than one system. Every joint is another place for air to escape. ENERGY STAR estimates a typical home loses 20–30% of the air moving through its ducts, and in a large home with several systems, that loss repeats on each one.

2. Signs Your Ducts Are Leaking

• The upstairs or a far wing stays warm on summer afternoons
• One system seems to run constantly while another keeps up fine
• A bonus room, addition or ADU never matches the rest of the house
• Weak airflow at registers at the end of long runs
• Higher bills than a home your size should need
• Ducts run through attics, crawl spaces or a garage

A duct leakage test measures each system separately so you know where to start.

3. Homes With Two or Three Systems

Larger homes often split heating and cooling between systems: upstairs and downstairs, or a main house plus a wing or garage conversion. Each has its own ducts and leaks. MaxSeal's Bay Area data includes several multi-system homes, listed by job ID.

Gains varied by system even within one house, so we test each one, and multi-system discounts help when sealing several. See the two-system and three-system case studies.

4. How Aeroseal Seals Ducts From the Inside

In a large home, many leaks sit inside walls and floor cavities that can't be reached without opening drywall. Aeroseal reaches them from inside the duct. We block every register, isolate the furnace and coil, pressurize the ducts and blow in a fine sealant mist. The particles stay airborne until they hit a leak, then collect at its edges until it closes.

Aeroseal seals holes up to about 5/8 inch, so we hand-repair larger gaps first. A computer shows leakage falling as the sealing runs. Aeroseal describes the sealant as non-toxic and ultra-low VOC. Read how it works.

5. Step-by-Step: Sealing Each System

Our Typical Aeroseal Duct Repair Process

1. Free consultation. In person or by video, we map out your systems and problem rooms.
2. Baseline testing. For each system, a calibrated Retrotec fan measures leakage at 25 Pascals (CFM25, cubic feet per minute at that pressure), and a flow hood reads every register.
3. Hand repairs. We reconnect loose runs, replace crushed flex duct and close gaps larger than 5/8 inch.
4. Aeroseal sealing. One system at a time, with live monitoring. Aeroseal recommends occupants are out during this stage.
5. Final test and report. You get before and after numbers for every system.

Each system usually takes about a day.

6. Staying Comfortable on Hot Afternoons

On a sunny summer afternoon, an attic can get much hotter than the outdoor air. Cool air leaking from attic ducts is lost, and leaky returns pull hot attic air back in. Rooms on the longest runs get the least air at the worst time.

Sealing keeps more cool air inside the ducts until it reaches the register. In our data, systems that started with the most leakage (450–650 CFM25) gained 64% airflow on average. More on comfort and eliminating uneven temperatures.

7. Air Quality and Smoke Season

Homes near the foothills have seen wildfire smoke drift into the South Bay in recent years. On those days, a leaky return duct in the attic or crawl space can pull outside air into your system without passing through the filter first.

Sealing the returns means more of your indoor air comes through the filter, with less attic dust and insulation fiber. We don't do lab air testing. If ducts are too dirty to seal, cleaning runs $500–$800. Learn more about air quality.

8. Energy Savings: What Changes After Sealing

These are MaxSeal's Bay Area-wide averages from 38 sealed systems, not Los Gatos or Saratoga results.

More delivered air lets each system reach the thermostat setting sooner. In theory, a 38% airflow gain cuts runtime by about 28%. Results vary by home. See lower energy bills.

9. Heat Pump Repairs and Installation: Start With the Ducts

Many people searching for heat pump repairs in Los Gatos or heat pump installation in Saratoga find us. MaxSeal doesn't repair or install heat pumps. We work on the ducts that carry their air.

That matters because heat pump supply air runs cooler than furnace air. If it loses heat through leaky attic ducts, it arrives at the register feeling cool, a problem often called cold blow. It can look like a failing heat pump when the ducts are the cause. Sealing first can save a repair call and helps a new unit perform as designed. California's Title 24 also generally requires duct testing when equipment is replaced. See heat pump cold blow and Title 24 duct testing.

10. Why Los Gatos and Saratoga Homeowners Choose MaxSeal

• Built for multi-system homes. We test and seal each system on its own, with multi-system discounts.
• Ducts only. No equipment to sell, so our recommendation follows your test numbers.
• Written proof. Before and after leakage and airflow for every system.
• Licensed dealer. CA License #1128398 and an authorized Aeroseal dealer. Aeroseal lists a 10-year residential warranty that dealers can pass on.
• Better overall performance. Tight ducts let your equipment deliver the airflow it was designed for. See system performance.