How many HVAC systems does a large Alamo house need?
That depends on the zone loads. We run Manual J by level and wing. Some houses do best with one zoned ducted system, others with two or three smaller ones. We recommend what the numbers support.
RESIDENTIAL HVAC · ALAMO, CA
Residential HVAC & Heat Pumps in Alamo, CA
Alamo homes are big, added onto, and often run on two or three systems that never talk to each other. We calculate each zone, pick the equipment to match, and replace the whole arrangement with heat pumps that work as one plan.
Remodels · Retrofits · Heat Pumps · Multi-Zone Systems
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- Serving the Bay Area since 2015
Alamo project types
Where we are usually called in around Alamo
Most Alamo calls start with a house that has uneven rooms, an aging furnace, or a remodel in the works. Here is how we sort those into scopes.
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Whole house
Multi-System Replacement
Two or three old furnaces and ACs replaced with heat pumps designed together, so each zone gets what its own load calls for.
Replacement & conversion -
Central
Zoned Ducted Heat Pumps
Variable-speed ducted equipment with zone dampers for two-story homes and long ranch wings, with returns sized for the airflow.
Heat pump installation -
Add-on
Bonus Rooms & Additions
Dedicated ductless or small ducted systems for the room that never matches the rest of the house.
HVAC for remodels -
New build
Custom Homes & Rebuilds
Load calculations, equipment rooms and duct layouts drawn with the architect before framing closes.
New construction HVAC -
Design only
Manual J Reports
A zone-by-zone load calculation for permits, second opinions, or comparing bids from other installers.
Manual J load calculations -
Air quality
Smoke-Ready Ventilation
High-capture filtration and balanced ventilation so a closed-up house stays fresh through smoky weeks.
Ventilation & IAQ
A published East Bay example
Whole-home heat pump remodel
View project →
High-end residential remodel
Hearst Remodel
One of our published multi-zone heat pump projects. It is a Berkeley remodel, not an Alamo job, but it shows how we plan equipment placement, refrigerant routing and coordination with a builder.
- Home type
- Existing home, remodel for sale
- System
- Fujitsu multi-zone ductless heat pump
- Mechanical scope
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- · Six indoor wall units
- · Two outdoor units
- · Wall-mounted outdoor brackets
- · Refrigerant routing and field coordination
Challenge
- Existing older home with limited equipment placement options
- Outdoor units required side-yard wall bracket mounting
- Finish-sensitive interior installation
- Coordination with the general contractor’s remodel schedule
3RDGEN scope
- Six-zone ductless heat pump installation
- GC-led remodel coordination
- Permit and inspection support
- Startup as part of the completed remodel scope
Outcome
The six-zone Fujitsu ductless system was installed, permitted, inspected, and completed as part of the home’s remodel-for-sale scope — delivering zoned heating and cooling without a conventional ducted retrofit.
Representative published remodel scope — location, photos, and full details on the project page.
View projectLocal projects
Heat pump & HVAC installs for Alamo homes
Recent installs by the 3rdGen crew that serves Alamo: ducted and ductless heat pumps, air handlers and ductwork.
Why size is not the answer
An Alamo house with a hot upstairs needs a better plan, not a bigger unit
Contra Costa County’s General Plan describes Alamo as mostly single-family, with ranch homes on large lots, estate properties and wooded hills. That mix means long floor plans, multiple levels and systems installed in different decades.
Our first step is splitting the house into zones and running a separate Manual J for each. The result usually shows where one system has been carrying a load it was never meant to carry.
From there we select equipment for each zone and design the ducts to match. The goal is that every room gets the airflow its load requires.
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Long ranch wings
Distant bedrooms at the end of an extended duct run often starve for air. Return sizing and trunk layout matter more than the unit itself.
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Second-floor heat
West-facing glass and attic exposure push upstairs cooling loads well above the main floor. A dedicated system or zoning solves it.
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Slopes and mature trees
Outdoor pads, line sets and condensate drains have to work with grades, drip lines and root zones.
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Smoke season
Homes near wooded hills benefit from better filtration and a ventilation plan that does not depend on open windows.
Alamo is unincorporated Contra Costa County, so HVAC permits go through the County rather than a city. We prepare the load calculation and equipment documentation for the application and schedule the inspections.
HVAC design in Alamo
Big Alamo houses are a zoning problem before they are a tonnage problem
Alamo is mostly single-family homes on large lots: ranch houses that have been added onto, two-story custom homes, and wooded hillside properties. Many have two or three separate furnace and AC systems installed at different times. Replacing them one for one rarely fixes the hot upstairs or the cold bonus room. We start by sorting the house into zones and calculating each one.
Design climate · Title 24 Climate Zone 12
- Winter design temp
- 31°F
- Summer design temp
- 96°F
Alamo sits inland of the Berkeley hills, so it gets real summer heat and a few frosty mornings. ACCA design conditions are about 31°F for winter and 96°F for summer. The cooling side drives equipment size here, and heat pumps sized to the cooling load cover the winter load with room to spare.
ACCA Manual J design data · Alamo, CA (ACCA micro-climate)
What we usually find in Alamo homes
Larger floor plans mean longer duct runs. We often see trunk lines stretched to rooms at the far end of a ranch wing, with returns that were never sized for the airflow the room needs. Those houses have comfort complaints that bigger equipment will not solve.
Additions are common. A family room or primary suite added in a later decade often hangs off an older system that was never recalculated for the extra square footage, so it is the first place to look when one part of the house never feels right.
Lot size helps with outdoor equipment placement. Hillsides and mature trees complicate it. We plan pad locations, line-set routes and condensate drainage with the slope and drip lines in mind.
Manual J by zone
On a large Alamo house we split the calculation by level and wing, so west-facing rooms with big glass and shaded bedrooms are not averaged together. The zone loads decide how many systems the house actually needs.
Manual S for multiple systems
When a house has two or three systems, we pick each one against its own zone load. That can mean a variable-speed ducted unit for the main floor and a small system for a bonus room, rather than three identical replacements.
Manual D: fixing the long runs
We measure static pressure and duct length before deciding what to keep. Undersized returns and long flex runs are the usual culprits, and we redesign or replace those sections when the numbers say they will choke the new equipment.
Smoke and air quality
Properties near wooded hillsides can see smoke in bad fire seasons. We spec higher-capture filtration and, where it makes sense, balanced ventilation so you can keep windows closed without the house getting stale.
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Multi-system heat pump conversion
Replace several aging furnaces and air conditioners with heat pumps coordinated as one design.
Replacement & conversion → -
Zoned ducted heat pumps
Variable-speed ducted equipment with zoning for two-story homes and long single-story wings.
Heat pump installation → -
Addition and primary-suite HVAC
Dedicated heating and cooling for added rooms so they stop borrowing capacity from an older system.
HVAC for remodels → -
Custom and new-construction HVAC
Mechanical design for rebuilds and large new homes, from load calculations through equipment rooms and ducts.
New construction HVAC → -
Pool house and guest-unit systems
Small heat pumps for detached units, sized to Title 24 and the building’s own load.
ADU heating & cooling → -
Filtration and fresh-air ventilation
ERV or HRV with high-capture filtration for homes that want clean indoor air during smoky weeks.
Ventilation & IAQ →
Permits, power and incentives in Alamo
Alamo is unincorporated, so mechanical permits go through Contra Costa County’s Department of Conservation and Development, not a city. We prepare the load calculation, equipment schedule and site plan the application needs and handle inspection scheduling.
Electric generation in Alamo defaults to MCE, with PG&E delivering the power. Programs such as TECH Clean California, BayREN and utility or MCE offers come and go, so we check what is currently open for your address and equipment before you commit.
Where we work around Alamo
Alamo and the surrounding San Ramon Valley, including Danville, Walnut Creek, Lafayette and Blackhawk.
Homeowner reviews
Trusted by Bay Area Homeowners
5.0
5 out of 5 stars from 207 Google reviews 207 Google reviews
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Mitsubishi mini-split installed with outstanding care. Indoor and outdoor units done right. High efficiency meant a meaningful federal tax credit too.
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Devin and his crew did a fantastic job installing AC for our whole house. High quality Mitsubishi equipment and a clean installation throughout.
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Devin is meticulous, methodical, and knowledgeable. Professional crew and a heat pump install we trust completely.
Photos from the installs above
Read all 207 reviewsHow we work
From a walkthrough to a balanced house
On an Alamo project, we figure out how many systems the home truly needs before we talk about equipment.
01 — Walk the house
We note each wing and level, existing equipment, attic and crawlspace access, and the rooms that never feel right.
02 — Zoned Manual J
A load calculation per zone using real windows, insulation and orientation, so the number of systems is based on math.
03 — Manual S and D
We select equipment against each zone load, then design ducts and returns to carry the airflow.
04 — County permit
The load report, equipment schedule and site plan go to Contra Costa County, along with any electrical changes.
05 — Installation
Pads, line sets, ducts and wiring are installed in a sequence that keeps the household livable.
06 — Commissioning
Refrigerant charge, register airflow and thermostat zones are verified one by one before inspection and handoff.
Beyond the equipment swap
A larger house means more pieces to line up
On Alamo jobs the work often spans attics, crawlspaces, garages and the side yard in one visit. We schedule those trades so the house is not torn up for weeks.
Before handoff we measure airflow at the registers and confirm each zone behaves the way the design said it would.
Tell us about the project-
Zone mapping
Each wing and level assigned to a system on paper before anything is ordered.
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Duct corrections
Returns and long runs rebuilt or replaced where the static pressure says they must be.
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Panel and sub-panel work
Circuit capacity confirmed for multiple heat pumps and added to the permit.
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Commissioning each zone
Charge, airflow and thermostats checked system by system.
Cost
What drives the cost of a heat pump project in a large Alamo home
Equipment is one line. The number of zones, duct repairs, panel capacity, pad and line-set routes on a sloped lot, and any ventilation you add usually move a big-house project more than the model you choose.
Scope Typical 3rdGen Project Range What drives it
Ducted heat pump, existing ducts usable $20k–$30k Equipment tier, capacity, controls, condenser location and access
Ducted heat pump + duct repair or resizing $25k–$45k Amount of ductwork replaced, crawlspace or attic access, return-air changes
Ductless multi-zone, 3–4 heads $25k–$40k Head type, line-set length, routing, concealment and finish conditions
Whole-home ducted + ductless combination $40k–$80k+ Multiple systems, zoning, ductwork, filtration, ventilation and architectural coordination
New construction system $20k–$50k+ Building size, system count, Title 24/design requirements and coordination with the build
ADU system $8k–$15k Zone count, head type, line-set routing, and whether the ADU shares the main house or stands alone
Electrical panel upgrade, when required $8k–$10k+ Service size, meter location, utility requirements and site conditions
Complex whole-home and design-build projects can exceed these ranges. Rebates and incentives may reduce your net project cost.
Project inquiry
Planning HVAC work on an Alamo home?
Tell us about the house, how many systems it has today, and which rooms give you trouble. Send plans if there is a remodel.
- Reviewed by a project lead, not a dispatcher
- We tell you if your scope is not a fit for us
- No high-pressure in-home sales appointment
Project Inquiry
Inquiry Sent
Thanks — your project details are on their way to 3rdGen. We’ll review them and follow up about the next step.
Working with your builder
We coordinate with your architect and contractor
For an Alamo addition or rebuild, we agree on equipment rooms, duct chases, ceiling heights and electrical capacity early, while those choices still cost nothing to change.
We work with architects and builders in Alamo and across the San Ramon Valley, or directly with homeowners.
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Architects
Mechanical systems coordinated around architecture, ceiling conditions, equipment locations, routing, and finish requirements.
Explore HVAC for architects -
General Contractors & Builders
Clear scope, scheduling, rough-in coordination, submittals, inspections, startup, and project handoff.
Explore HVAC for builders & GCs -
Mechanical Engineers
Field execution, equipment selection, controls coordination, submittals, installation, and commissioning aligned with the mechanical design.
Explore engineering coordination -
Homeowners
Already assembling your own project team? We can take ownership of the mechanical scope and coordinate directly with the other professionals involved.
Start a residential project
Mitsubishi Electric
Proud Mitsubishi Electric Diamond Contractor
As a Mitsubishi Electric Diamond Contractor, we design and install ducted, ductless, and multi-zone systems for Bay Area homes, with factory-trained crews and longer warranty options on qualifying residential installs.
Mitsubishi is not automatically the answer to every home. We start with what the project requires and recommend the system that makes sense.
12 Year Parts &
Compressor Warranty
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.
FAQ
Common Questions
Answers for large homes, zoning and permits in Alamo.
My upstairs is always hotter than downstairs. Will a bigger system fix it?
Usually not. The cause is often attic heat, west glass and a duct layout that favors the main floor. A separate upstairs system or zone dampers with properly sized returns tends to work better.
Can I replace one old furnace now and the others later?
Yes, as long as the plan covers the whole house. We design the full layout first so each phase fits it, and so you do not end up with equipment that fights the next piece.
Do I need a permit for a heat pump in Alamo?
Yes. Alamo is unincorporated, so Contra Costa County issues the HVAC permit. We prepare the submittal and coordinate inspections.
Who supplies electricity in Alamo, and are there rebates?
PG&E delivers it and MCE is the default generation provider. State, regional and utility incentives such as TECH Clean California and BayREN change often, so we check what is available before you sign.
Will a house this size need an electrical panel upgrade?
Sometimes. Two or three heat pumps plus a water heater or EV charger can exceed an older panel. We run the load calculation and tell you before ordering equipment.
What about wildfire smoke?
We can specify higher-capture filtration in the air handler and add balanced ventilation, so you can keep windows closed during smoky days and still have fresh air.
Nearby service areas
Heat pump and HVAC design near Alamo
Project Inquiry
Inquiry Sent
Thanks — your project details are on their way to 3rdGen. We’ll review them and follow up about the next step.