Residential HVAC · Mill Valley, CA
Residential HVAC in Mill Valley, CA
Heat pumps, ducted systems, mini-splits, whole-home replacements, and remodel HVAC for Mill Valley homes where hillside access, sound, routing, and design intent matter.
Project photo
[ img ] Mill Valley · residential design-build
2015
In business since
J · S · D
In-house Manual calcs
C-20 · C-36
CA Lic. 1086898
Local context
Heating & cooling designed for Mill Valley
Mill Valley includes wooded hillside homes, mid-century residences, remodels, and custom properties where access, equipment sound, routing, and finish-sensitive mechanical work matter.
Areas we often work in: Downtown Mill Valley · Tamalpais Park · Sycamore Park · Blithedale Canyon · Alto · Homestead Valley
Marin County · permits pulled as part of full-system design-build scopes
Climate
A Bay-influenced climate
Marine influence keeps much of Mill Valley mild, while hillside sun exposure and warmer inland pockets create meaningful room-by-room differences. Manual J sizing should reflect the actual site and envelope.
Capabilities
Full-system HVAC for Mill Valley homes
Remodels, whole-home replacements, heat pump conversions, and multi-zone comfort — planned with Manual J, S, and D where the project needs it.
Heat pump conversions
Gas-to-electric and high-efficiency heat pump upgrades sized for your home, with distribution and electrical needs planned up front.
Whole-home HVAC replacement
Full-system retrofits when ducts, equipment, zoning, or efficiency need a real redesign — not a same-size swap.
Ductless & multi-zone
Room-by-room comfort with ductless or ducted multi-zone layouts where the home needs flexible zoning.
Zoned comfort & VRF
Multi-zone ducted and ductless layouts, including VRF where larger or multi-level homes need quiet, flexible zoning.
Duct design & Manual D
Manual D–informed duct layouts so rooms get the airflow the load calculation calls for.
Indoor air quality & filtration
Upgraded filtration, sealed returns, and distribution strategies that help during wildfire smoke and allergy seasons.
Process
From first call to startup in Mill Valley
01
Tell us about your home
Share location, timeline, plans if you have them, and what is not working today — or what your builder has scoped.
02
Size & design the system
We use Manual J, S, and D where the project needs it to match equipment, ducts, and zoning to the actual house.
03
Coordinate & install
Design-build field work with your GC or architect around access, finishes, sequencing, and clean rough-in.
04
Startup & handoff
System startup, basic orientation, and documentation so you know how the new system is meant to run.
Why 3rdGen
Built for whole-home projects in Mill Valley
Design-build installs
Field execution by the team that sized and specified the system — before equipment is ordered.
In-house Manual J · S · D
Load, equipment, and duct decisions based on the home — not square-footage rules of thumb.
Licensed design-build
C-20 HVAC and C-36 Plumbing · CA Lic. 1086898 · in business since 2015.
Common Questions
Frequently asked in Mill Valley
What heat-pump systems work well in Mill Valley?
Ducted, ductless, and mixed heat-pump systems can all fit. The right approach depends on the home’s loads, existing ducts, zoning goals, access, and architectural constraints.
Can you work on hillside properties?
Yes. Hillside access affects equipment placement, delivery, drainage, line-set routing, and service clearances, so those conditions are reviewed during design.
Do you work with architects and remodel contractors?
Yes. We coordinate mechanical design, equipment locations, routing, rough-in, electrical needs, startup, and commissioning with the existing project team.
Can existing ducts be reused?
Sometimes. We evaluate condition, leakage, sizing, return paths, and room airflow before deciding whether existing ducts should be reused, modified, or replaced.
Do you handle permits and inspections?
Permit and inspection coordination are included in the design-build scopes we install.
Marin County · Service area
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