Skip to content 
ADU HVAC and Electrical in San Jose, CA
An ADU needs its own heating, its own cooling, and its own power feed. We handle all of it, and we coordinate with your builder so it lands on schedule.
Serving Santa Clara & San Mateo Counties
An ADU Is Its Own System, Not a Smaller Version of Your House
An ADU is a separate conditioned space with its own heat load, usually built with better insulation than the main home and often with a very different window layout.
That combination catches people out. A well-sealed 600-square-foot unit with one large window facing west behaves nothing like 600 square feet of the main house. It holds heat longer, and it gains it faster on a summer afternoon.
Size the equipment off the square footage alone and you end up with a unit that short-cycles, runs loud, and never feels right. We calculate the actual load for the finished structure, and we do it before anyone orders equipment.
What You Get
Every ADU project we take on includes the following, whether we start from plans or from a finished shell:
Heating and Cooling Sized to That Load
A ductless mini-split is the usual answer. A studio or compact one-bedroom typically runs on a single indoor unit. Once there is a closed bedroom door, a second zone earns its place.
Ventilation and Hot Water
Kitchen and bathroom ventilation is part of our scope. For hot water, a heat pump water heater fits the space and the electrical budget better than a standard electric tank.
Subpanel and Circuits
Most ADUs run off a subpanel fed from the main house, with the unit’s circuits landed on it. We size the feed, run it, and set the panel.
Commissioning and Handoff
We verify the system operates correctly and show you or your tenant how the controls work.
Warranty
HVAC installation labor is covered for 3 years, extending up to 12 years with annual maintenance from year 4 onward, with the first two maintenance years on us. Electrical labor is covered for 1 year. Equipment carries the manufacturer’s own coverage, up to 12 years for HVAC and up to 10 years for electrical components.
Four Kinds of ADU, Four Different Jobs
The type of ADU changes both the mechanical and the electrical answer.
Detached
Best for: yard space, full separation
A separate structure with its own power run from the main house, which means a trench and an underground feed. Heating and cooling are independent from day one.
Attached
Best for: additions along an existing wall
Sometimes the main system can be extended, more often it should not be, because the addition throws the whole house out of balance. We check which applies before anyone commits.
Garage Conversion
Best for: existing footprint, faster build
The most common one in San Jose. Garages were never insulated or conditioned, and the existing circuits were sized for a door opener and a freezer. Both need rethinking.
Junior ADU Inside the House
Best for: carving a unit out of existing space
The walls are already there, so the questions become whether the main system can serve the unit separately and how the circuits get divided.
Will Your Existing Service Handle an ADU?
This is the question every ADU project starts with, and the one most often answered wrong. We answer it first, before equipment is specified and before your builder locks the schedule.
We calculate what the finished unit will draw and compare it against what your service actually has left. A full service upgrade is needed less often than owners are told. Where capacity is close, load management is usually the faster and cheaper path.
This Service May Cost Less Than You Think
Rebates and incentives are available for qualifying equipment in Santa Clara and San Mateo Counties, and ADU installations often qualify. Local utility and state energy programs can be combined, which is where the numbers start to matter.
Terms and amounts change regularly, so we confirm what your project is eligible for during the free estimate and handle the paperwork ourselves, at no charge.
From Plans to Final Inspection
Step 1
Free Assessment
We review the plans or walk the space, calculate the load, and check what your main service can support. You get a written scope.
Step 2
Rough-In Coordination
We schedule our rough-in around framing and drywall with your builder. That window is short, so we book it early.
Step 3
Installation
Equipment set, circuits run, subpanel landed, feed trenched where the unit is detached.
Step 4
Inspection, Commissioning, Handoff
We meet the inspector, verify the system, and walk you or your tenant through the controls.
Why Owners and Builders Bring Us In
Both Licenses, One Load Calculation
The equipment and the electrical feed have to be designed against the same numbers. When two companies do that separately, the numbers do not match and somebody eats the difference.
Built Around Your Construction Schedule
Rough-in has a narrow window and everything downstream depends on it. We coordinate directly with your general contractor and show up when the framing is ready, not two weeks after.
We Know The California Building Code
These projects run regularly across Santa Clara and San Mateo Counties with no hustle.
Authorized Dealer & Installer
Recently Completed in the Bay Area
Every project shown here was completed by our in-house team – permitted, inspected, and under full warranty.
What Our Customers Say
Commercial Heat Pump Installation
We install heat pump systems for commercial properties across the Bay Area – office buildings, retail spaces, multi-unit residential, and light industrial. Commercial projects follow the same process: load calculation, proper permitting, licensed installation, city inspection.
For commercial inquiries, contact us directly to discuss scope and timeline.
Frequently Asked Questions
Can my existing electrical service handle an ADU?
In most cases it can. Homes with a modern service usually have room once the load is calculated properly. We measure what your house actually uses rather than adding up nameplate ratings, which is what leads people to think they need an upgrade they do not.
Can the ADU be metered separately from the main house?
That depends on your utility and how the unit is set up, and it is a request you make to the utility directly.
Is one mini-split enough for a whole ADU?
For a studio or a compact one-bedroom, usually yes. Once the layout has a closed bedroom door between the unit and the rest of the space, a second zone is worth it. The load calculation settles this, not the square footage.
We already have an ADU with no real heating or cooling. Can you retrofit it?
That is a job we do often. We assess what is already in the space, calculate the load for how the unit is actually being used, and tell you what the existing circuits can support before recommending equipment. Retrofits are usually simpler than owners expect, because the structure is finished and nothing has to be coordinated around a build schedule.
Can you work alongside my general contractor?
Certainly. We handle our own permits and inspections for the mechanical and electrical scope and coordinate the schedule directly with your GC.
Get a Free Estimate for Your ADU
Send us your request and we will get back to you shortly
- go@serviceozone.com
- Serving Bay Area, 24/7
Serving the Greater Bay Area
* and other cities across Santa Clara and San Mateo counties
