Residential HVAC Design-Build · Bay Area

Residential HVAC Design-Build for Heat Pumps, Remodels, Retrofits, and New Construction

3rdGen Heating & Cooling provides project-based residential HVAC design-build support for homeowners, builders, architects, and remodelers. We specialize in systems where comfort, equipment placement, ductwork, zoning, finish details, and long-term performance matter.

We do not provide emergency repair, routine maintenance, tune-ups, or small service calls.

Mitsubishi Electric H2i — outdoor unit & air handler
  • 5.0 Google Rating 5.0 out of 5 stars
  • 850+ Systems Installed
  • 11 Years Bay Area Design-Build
  • Mitsubishi Diamond Contractor
  • Manual J / S / D
  • CA Lic. 1086898

Factory Certified & Trained

HVAC Services

Project-Based Residential HVAC Services

Heat pump installations, full-system replacements, remodels, retrofits, new construction, ADUs, and Manual J/S/D-supported design-build for Bay Area homes where comfort, equipment placement, and long-term performance matter.

Project fit

Project-Based Residential HVAC

3rdGen supports premium residential HVAC work for homeowners, residential GCs, and architects planning heat pump upgrades, full-system replacements, remodels, retrofits, new construction, and ADUs — not emergency repair or routine maintenance.

Built for projects like these

  • 01 Heat Pump & All-Electric Upgrades

    Furnace-to-heat-pump conversions, gas-to-electric HVAC upgrades, and full-system electrification sized with Manual J/S/D.

  • 02 Remodels & Renovations

    HVAC coordinated with architects and GCs — equipment placement, duct routing, finishes, and post-remodel comfort.

  • 03 New Construction & ADUs

    Mechanical planning before rough-in is locked in — custom homes, additions, garage conversions, and permitted ADUs.

  • 04 Full-System Replacements & Retrofits

    Whole-home HVAC replacement and retrofits where sizing, ductwork, zoning, and comfort correction matter.

Not what we do

  • Emergency Repair

    No-heat, no-cool, or same-day service calls for existing systems.

  • Maintenance & Tune-Ups

    Annual tune-ups, filter changes, duct cleaning, or service contracts on equipment we did not install.

  • Small Service Calls

    Thermostat swaps, minor component fixes, mini-split cleaning, or other one-off repairs.

  • Low-Ticket Swaps

    Like-for-like equipment replacements or budget furnace swaps without design input.

Local authority

Local HVAC Design-BuildAcross the Bay Area

Serving San Francisco, Marin County, the Inner East Bay, Lamorinda, Walnut Creek, Tri-Valley, Wine Country, and the South Bay with residential HVAC systems designed around Bay Area homes, remodels, additions, energy goals, and comfort challenges.

San Francisco residential HVAC design-build service area for 3rdGen Heating & Cooling
San Francisco residential HVAC design-build service area for 3rdGen Heating & Cooling

San Francisco

San Francisco residential HVAC design-build service area for 3rdGen Heating & Cooling

San Francisco HVAC Design-Build

San Francisco homes often need HVAC systems that work within tight mechanical spaces, older framing, flat roofs, historic construction, and dense urban layouts. 3rdGen Heating & Cooling designs and installs residential HVAC systems for remodels, additions, replacements, heat pump upgrades, and high-performance comfort projects throughout San Francisco.

Cities served

1

Common homes
Victorians, Edwardians, flats, condos, townhomes, historic homes, and narrow-lot single-family homes.
Common projects
HVAC replacement, heat pump installation, ductwork, zoning, ventilation, remodel HVAC, and Manual J planning.
View all service areas

Manual J · S · D

Designed Before It's Installed: Manual J, S & D

Manual J/S/D helps ensure equipment sizing, system selection, duct design, and comfort decisions are based on the actual home rather than guesswork. Manual J determines load. Manual S matches equipment. Manual D supports duct and airflow design — for heat pumps, remodels, new construction, and full-system replacements.

Manual J: Heating & cooling loads

Manual J determines the heating and cooling load for each room and for the home as a whole.

  • Floor area
  • Room-by-room dimensions
  • Ceiling height
  • Orientation
  • Window area
  • Window U-factor / SHGC
  • Insulation levels
  • Infiltration / air leakage assumptions
  • Internal gains
  • Occupancy assumptions
  • Local design temperatures
  • Duct location and losses
  • Envelope conditions
  • Zoning strategy

Manual J helps determine what the home actually needs, instead of guessing based on square footage or existing equipment size.

Manual S: Equipment selection

Manual S matches HVAC equipment capacity to Manual J results — not nameplate tonnage alone.

  • Equipment capacity is not just nameplate tonnage
  • Heat pump capacity changes with outdoor temperature
  • Equipment must be matched against calculated heating and cooling loads
  • Oversizing can cause short cycling
  • Undersizing can fail to meet design load
  • Proper matching affects comfort, noise, efficiency, and lifespan

Manual S helps select equipment that can actually perform correctly in the home’s conditions.

Manual D: Duct & airflow design

Manual D supports duct sizing, layout, and airflow so conditioned air reaches each room.

  • Duct sizing
  • Static pressure
  • Supply airflow
  • Return airflow
  • Room-by-room CFM needs
  • Duct transitions
  • Register placement
  • Flex duct limitations
  • Return path issues
  • Air balancing
  • Noise and velocity considerations

Even the right equipment can perform poorly if the ductwork and airflow path are wrong.

Rebates & Financing Support

We find the incentives — and do the paperwork.

TECH Clean California

Statewide heat-pump incentives that can stack with utility and federal programs. We confirm eligibility and submit on your behalf.

Federal tax credits (25C)

Federal tax credit documentation for qualifying heat pump and high-efficiency equipment where your scope meets current IRS requirements. We provide install records and eligibility guidance — your tax advisor confirms final credit amounts.

BayREN & local rebates

Regional and county programs — including BayREN Home+ and local electrification rebates where available. We align equipment and Manual J documentation to program specs before install.

Utility rebates (PG&E)

PG&E and community-choice rebates in our service areas — including SJCE EcoHome Network, SVCE FutureFit, and Peninsula Clean Energy pathways where your project qualifies.

0% & low-APR financing

Synchrony financing — 0% for 36 months, no-interest-if-paid-in-full at 6 or 18 months, and fixed APR plans from 5.99% on qualifying design-build scopes. We provide scope clarity before you apply.

Rebate availability can change by location, utility, equipment type, program funding, and eligibility. Final approval is determined by the program administrator.

Financing

Comfort now, paid over time.

Spread the cost of your HVAC upgrade with Synchrony financing — promotional 0% and deferred-interest options plus low fixed-rate plans for qualifying design-build scopes.

  • No interest if paid in full within 6 or 18 months
  • 0% interest for 36 months on qualifying purchases
  • Fixed payment plans from 5.99% APR

Current promotions

  • 6 months No interest if paid in full Plan 600
  • 18 months No interest if paid in full Plan 603
  • 36 months 0% interest Plan 982
  • 5.99%–12.99% Fixed APR until paid in full
See all promotions →
Synchrony

0%

Interest for 36 months on qualifying purchases

  • 6 moNo interest if paid in full
  • 18 moNo interest if paid in full
  • From 5.99%Fixed APR until paid in full
Get started

Subject to credit approval · Promotional terms vary by plan

Financing through Synchrony is subject to credit approval. Promotional rates, plan numbers, and availability may change. Minimum monthly payments required. 3rdGen is not a lender and does not set financing terms.

Mitsubishi Electric Heating and Air Conditioning
Mitsubishi Electric Diamond Contractor

Certified Partner

Proud Mitsubishi Electric Diamond Contractor — Elite.

Our Elite Diamond status puts us in the top tier of contractors nationwide for design, installation, and service — and unlocks the strongest warranties available on Mitsubishi systems.

12-year warranty

Extended parts & compressor coverage on qualifying Diamond installations.

Factory-trained crews

Ongoing manufacturer training on the latest hyper-heat systems.

Priority support

Direct factory escalation if anything ever needs attention.

Homeowner reviews

5.0 5 out of 5 stars (160 reviews)

Trusted by 160+ Bay Area Homeowners

  • “Yesterday we had a Mitsubishi mini-split unit installed by Devin, Will, and Chris. The work was done in outstanding fashion — both indoor and outdoor units installed with care. Plus, I can get about a $2,500 federal tax credit because of the high efficiency of the system.”

    Gary Marks

  • “Devin and his crew did a fantastic job to install AC for our whole house. They only use high quality appliances from Mitsubishi — clean installation.”

    Christian Vuerings

  • “Devin is absolutely amazing — meticulous, methodical, and knowledgeable. He and his crew traveled all the way to Modesto to install two mini-splits in my duplex.”

    D C

Common Questions

Residential HVAC projects, answered.

Heat Pumps

Can a heat pump replace my furnace?

Yes — whole-home gas-to-electric conversions are a core part of our work. We size heat pumps for calculated heating and cooling loads, plan electrical capacity, and coordinate distribution — not a same-size swap based on your old furnace label.

Do heat pumps work in Bay Area weather?

Modern cold-climate heat pumps perform well in Bay Area winters and summers when sized with Manual J and installed with proper distribution. Coastal microclimates and inland heat spikes are why we engineer each home — not assume one product fits all.

What brands do you install?

We are Mitsubishi Electric specialists and design around the best technology for your home — ducted, ductless, or mixed layouts sized with Manual J/S/D, not rule-of-thumb equipment swaps.

Load Calculations

What is a Manual J load calculation?

Manual J is the ACCA standard for calculating heating and cooling loads room by room based on your home’s envelope, windows, orientation, and local climate — not square footage rules of thumb. We use it to size equipment and duct systems so your system performs in real Bay Area conditions.

Why not size HVAC equipment by square footage?

Square-footage rules ignore insulation quality, window area, shading, air leakage, and how your home actually gains and loses heat. Oversized equipment short-cycles, wastes energy, and struggles with comfort and humidity. Manual J matches capacity to measured loads.

What are Manual S and Manual D?

Manual S selects HVAC equipment that matches Manual J loads without oversizing. Manual D sizes and lays out duct systems for proper airflow and static pressure. Together with Manual J, they form the engineering backbone of our design-build installs.

Cost, Rebates & Financing

Are rebates available for heat pump projects?

Many Bay Area projects qualify for federal tax credits, TECH Clean California, HEEHRA (income-qualified), and utility programs we support — including SJCE EcoHome Network, SVCE FutureFit, and Peninsula Clean Energy approved-contractor rebates — when equipment, sizing, and documentation meet current requirements. We design installs for program eligibility and provide documentation — we do not issue rebates or guarantee specific dollar amounts.

Is financing available?

We are not a lender. We provide scope clarity, invoices, and installation documentation that support financing applications. Homeowners often use Synchrony or their own bank or credit union — we help you understand what paperwork your lender typically needs.

Service Area

What areas do you serve?

We serve homeowners across the San Francisco Bay Area — East Bay, San Francisco, Marin, Peninsula, Lamorinda, Walnut Creek, Tri-Valley, and South Bay — on design-build residential HVAC projects. We do not provide emergency repair or maintenance on existing systems we did not install.

Process

Do you help with permits?

Yes. Permit, Title 24, and inspection coordination are part of our design-build scope — not a surprise add-on at the end. We retain load calc and equipment documentation your jurisdiction and rebate programs commonly require.

Do you offer HVAC repair, maintenance, or emergency service?

No. We focus on project-based residential HVAC — heat pump installations, full-system replacements, remodels, retrofits, new construction, and ADUs. We do not provide emergency repair, routine maintenance, tune-ups, filter changes, or small service calls.

Company

What is the difference between 3rdGen Building Systems and 3rdGen Heating & Cooling?

3rdGen Building Systems is the licensed mechanical contractor for commercial, industrial, and project-team work. 3rdGen Heating & Cooling is the residential HVAC division / DBA focused on homeowner design-build — heat pumps, remodels, ADUs, and whole-home replacements.

Field Notes & Home HVAC Insights

What we're learning in the field.

All field notes →

Practical notes on heat pump conversions, load calculations, remodel mechanical decisions, and design-build coordination for Bay Area homes.

Ready to begin your project?

Tell us about your home — we’ll follow up with next steps and a design consultation.