Indoor Air Quality

Better air quality is a system problem, not a filter you grab off a shelf

$99 diagnostic

Most of the calls we get about “air quality” aren’t really about a filter. It’s a house that’s dusty no matter how often you clean, a room that always smells musty, allergies that never let up, or a wildfire smoke week that made everything worse. The instinct is to grab a higher-rated filter or a gadget off a shelf. Before we sell you either, we check what your system can actually move air through. A filter that’s too restrictive or a duct that’s leaking will undo whatever you install on top of it.

A higher MERV number is not automatically cleaner air. MERV stands for Minimum Efficiency Reporting Value, and the scale runs 1 to 16 under the ASHRAE standard. A basic MERV 8 filter, the standard builder-grade pleated replacement, catches dust, pollen, and lint. MERV 13 catches much finer particles, including smoke and bacteria-sized droplets, but a denser filter medium also resists airflow more. Most residential systems are designed to run at or below 0.5 inches of water column of total static pressure. Squeeze a MERV 13 into a standard 1-inch filter slot and you can push that number well past design spec, which means the blower motor works harder, runs hotter, and wears out years before it should, and in the worst case the evaporator coil starts icing over because not enough air is moving across it to keep it warm. A 4-inch media filter housing fixes the tradeoff: more surface area, much less resistance, and it holds a MERV 11-13 filter without the airflow penalty. If your system has a 1-inch slot and an older single-speed blower, we check static pressure before recommending anything past MERV 8. If it has room for a 4-inch cabinet, or a variable-speed blower that can compensate, MERV 11-13 is usually fine. We cover the full mechanics in MERV 13 Filters: Better Air Quality but Harder on Your HVAC System.

If the house stays dusty no matter what filter you run, the dust is probably getting in downstream of the filter. Return ducts that leak pull in whatever air surrounds them, and in most Bay Area attics and crawl spaces that’s dust, insulation fibers, and unconditioned outside air, none of which passes through your filter at all before it lands on your furniture. ENERGY STAR puts typical duct leakage at 20 to 30 percent of total system airflow. We find it with a duct pressurization test: seal the registers, pressurize the system with a calibrated fan, and measure exactly how much air escapes and roughly where. Sealing the return side properly, mastic on accessible joints, aerosol injection like Aeroseal for runs buried in a wall, is often the single biggest air quality fix available in a home, and it’s the one most contractors skip because a new filter cabinet is more visible than duct work in the attic. Full diagnosis in Signs Your Air Ducts Are Leaking (and What It Costs You).

A media filter cabinet and a UV lamp solve different problems, not the same one. A 4-inch media filter rated MERV 11-13 is the upgrade we install most, both on new equipment and retrofit onto an existing system when the return trunk has room for the housing. It’s the best air-quality-per-dollar move for wildfire smoke season and everyday dust and pollen. A UV-C lamp mounted near the evaporator coil is a different tool: it keeps the coil and air handler interior free of mold and cuts down musty smells, but residential air moves through the system too fast for a single lamp to meaningfully sanitize the air passing by. If you’ve got coil mold or a persistent musty smell from the vents, a UV lamp is the right call. If you’re trying to cut down dust and allergens, the media filter is what does that job. We don’t install bipolar ionizers; the evidence on real-world particle reduction is thin and some models put out ozone that isn’t CARB-compliant for California.

Humidity is part of air quality, and your AC only handles it while it’s actually running. Cooling pulls moisture out of the air as a byproduct of the cycle, but an oversized system reaches the thermostat setpoint fast and shuts off before it’s dehumidified much of anything, and on a cool, foggy Bay Area morning your AC may not be running at all while indoor humidity climbs. Target range is 45-50% relative humidity. Below 30% and you get dry-air irritation; above 60% and you’re in the range where mold and dust mites thrive. For crawl-space homes and coastal fog zones like Daly City and Pacifica, where the AC alone can’t keep up, a whole-house dehumidifier ties into the ductwork and runs on its own humidistat, independent of the thermostat. For everyone else, a $15 hygrometer left in the room for a week tells you whether you actually have a problem worth spending money on. More in Whole-House Dehumidifier: When It Makes Sense and When It Doesn’t.

What’s included in an indoor air quality visit:

• Static pressure reading on both sides of the filter
• Return duct inspection, with a pressurization test where leakage is suspected
• Filter housing check: what your current slot can hold, and whether a 4-inch cabinet retrofit makes sense
• Indoor humidity reading against the 45-50% target
• Evaporator coil condition check (mold, dust buildup, icing history)
• Written recommendation, priced and explained, no pressure to buy equipment you don’t need

Wildfire smoke season: if you’re running MERV 13, check the filter monthly during active smoke events and plan to change it closer to every 60 days than every 90; it loads up faster than a MERV 8 does. Running the system in fan-only mode gets you filtration passes without the cooling cycle if you want the air moving on a smoky day without running the compressor.

We’re EPA 608 certified for anything that touches refrigerant, which is what coil work and sealed-system repairs need, and CSLB #1136642 licensed for the ductwork and electrical involved. The $99 visit covers the full assessment: static pressure, duct leakage, and a humidity reading, credited toward the repair.

What makes us different

Factory-trained on Daikin. Direct manufacturer training, not just certification paperwork.

Owner reviews every estimate. Every estimate gets my personal review before it reaches you. For installations and complex service, I meet you on-site. For routine calls, our trained technicians arrive with my license number on the invoice.

EPA 608 certified · MCE participating. Refrigerant-handling certified, MCE Clean Energy participating contractor for heat-pump incentives.

What to expect

Every job, repair or install, follows the same rhythm. No upsells dressed as "package tiers." No "today only" pricing. If the answer is "wait six months and re-evaluate," that is what we will say.

1. 01
   On-site visit

   Andrew measures, photographs, and asks questions about your existing system. $99 diagnostic, credited toward the repair.

2. 02
   Written estimate

   Line-itemed, model-named, sized to a Manual J calculation. Sent same day, never verbal-only. Walk-aways are fine; no pressure.

3. 03
   Scheduled install

   Same crew start to finish. Permit pulled where required. 10-year parts warranty; labor is 2 years standard, extended to 10 with our bi-annual maintenance plan in force.

4. 04
   Follow-through

   We check the install at six months. If your utility bill did not move in the right direction, that is on us; we go back and find out why.

The diagnostic is ninety-nine dollars and we credit it toward any repair over two hundred. If the answer is ‘your system is fine, here are the logs, call us next year,’ that is what the estimate will say.

Indoor Air Quality: common questions

Cities where we do this work

Tier-1 service area for indoor air quality: Danville · San Ramon · Alamo · Blackhawk · Pleasanton · Dublin · Walnut Creek · Lafayette · Alameda · Piedmont · Pleasant Hill · Atherton · Hillsborough · Los Altos Hills · Burlingame · Millbrae .

Also across the Bay Area: Livermore · Concord · Orinda · Moraga · Martinez · San Jose · Santa Clara · Cupertino · Los Gatos · Saratoga · Sunnyvale · Mountain View · Palo Alto · Los Altos · Menlo Park · Oakland · Berkeley · Richmond · El Cerrito · Albany · Fremont · Hayward · Union City · Newark · San Leandro · Castro Valley · Milpitas · Woodside · Portola Valley · Daly City · South San Francisco · San Bruno · Pacifica · San Mateo · Foster City · Belmont · San Carlos · Redwood City · East Palo Alto · Half Moon Bay . See full service area.