Ductless Mini-Split Installation
Ductless heat pumps for Craftsman bungalows, additions, converted garages and hot upstairs rooms, with head styles chosen room by room.
Learn moreHeat Pumps & Ductless in Pasadena, CA
ADU heating and cooling in Pasadena, sized for small backyard units and Title 24
Heat pump systems for backyard ADUs, garage conversions and junior units, sized correctly for small spaces and built to pass inspection.
- Answering 24/7
- Price quoted before work
- Pasadena and nearby cities
Quick answer
Most Pasadena ADUs are heated and cooled with a small heat pump, either a ductless mini-split or a compact ducted system, because the floor area is small and new construction must meet Title 24 energy rules. Marco's sizes the system for the actual square footage and insulation, coordinates with your builder, and handles the mechanical permit where the city requires one. Call (626) 879-0711.
ADU Heating & Cooling
What adu heating & cooling covers at your home
Accessory dwelling units are going up all over Pasadena and the San Gabriel Valley, from detached backyard cottages to garage conversions and junior units carved out of an existing house. They share one challenge: the space is small, often between 300 and 1,200 square feet, and the heating and cooling system has to be sized for that. A system designed by rule of thumb for a bigger house will short cycle, feel clammy and waste power.
Marco's Heating & Air designs and installs ADU heating and cooling for homeowners, builders and architects. We work from your plans or the finished framing, calculate the real load, choose between ductless and small ducted heat pumps, and plan the condensate, electrical and line set details so the system passes inspection the first time. If the ADU is already built and the system is not working well, we can fix that too.
Warning signs
Signs your ADU project needs HVAC planning now
Plans heading to plan check
Title 24 energy compliance is reviewed with your plans. Choosing the heating and cooling system early keeps the energy report, plans and final install in agreement.
Garage conversion underway
Converted garages often have thin walls, a concrete slab and a single large door opening. They need careful sizing and placement to stay comfortable year round.
Builder suggests extending ducts
Tying a backyard ADU into the main house system rarely works. Separate units give the ADU its own control, its own utility use and better comfort.
Unit is hot every afternoon
A finished ADU that overheats in summer may have an undersized system, a poorly placed head, or missing insulation that the load calculation should have caught.
Renting the ADU out
Tenants expect reliable heating and cooling with their own thermostat. A properly installed system keeps calls and complaints down and protects the investment.
Rebuilding after the fire
Families rebuilding homes and ADUs in Altadena after the Eaton Fire need heating and cooling that meet current energy rules from the start.
Sizing heating and cooling for a small floor plan
A 500 square foot ADU with new walls, good windows and Title 24 insulation may need only 9,000 to 12,000 BTU of cooling, far less than most people guess. Garage conversions with a slab floor and big west facing windows can need more. We calculate the load from the actual walls, ceiling, windows and orientation instead of using a square foot rule, then pick equipment that matches.
Small spaces are where oversizing does the most harm. An oversized unit cools a studio in a few minutes, shuts off, and leaves moisture in the air. Inverter heat pumps help because they can run at low speed most of the day. Even so, we try to land as close to the calculated load as the available equipment sizes allow.
Ductless, compact ducted or a small packaged unit
For a studio or one bedroom ADU, a single zone ductless mini-split with a wall head is often the simplest and most efficient choice. For a two bedroom unit, a multi zone mini-split with a head in each bedroom and one in the main room keeps every space comfortable. Owners who prefer no visible equipment often choose a slim ducted mini-split hidden in a soffit or attic space feeding short ducts.
Each approach has trade-offs in cost, appearance, noise and service. We walk through them with you and your builder, usually during framing, when line set routes, condensate drains and ceiling openings are easiest to plan.
- Single zone wall head: lowest cost, best for studios and open plans
- Multi zone mini-split: one outdoor unit, separate control in each room
- Slim ducted mini-split: hidden equipment, short ducts, needs soffit or attic space
- Separate electrical subpanel or circuits planned with the ADU electrical design
Title 24, permits and working with your builder
New ADUs in California must meet Title 24 energy rules. The energy compliance report filed with your plans spells out the heating and cooling system efficiency, duct location and insulation, and sometimes testing requirements such as duct leakage or airflow checks. If the installed system does not match the report, the final inspection can stall.
We review the energy report before we quote, match the equipment to it, and provide the paperwork the inspector expects. We handle the mechanical permit where the city requires one, or work under your builder's permit when that is how the project is set up. Clear coordination on rough-in timing, electrical circuits and exterior equipment location keeps the rest of the job on schedule.
Step by step
How we plan an ADU system
- 1
Review the plans
We read the floor plan, elevations and Title 24 energy report, or visit the framed unit, to understand rooms, windows, ceiling heights and where equipment can go.
- 2
Calculate the load
A room by room load calculation sets equipment size, with attention to west windows, slab floors in garage conversions, and the ADU's orientation on the lot.
- 3
Quote and coordinate
You and your builder get a written quote with equipment, line sets, condensate plan, electrical needs and rough-in timing so other trades can plan around it.
- 4
Rough-in and set
Line sets and condensate lines go in before drywall. After finishes, we mount heads, set the outdoor unit and make the final refrigerant and electrical connections.
- 5
Startup and inspection
The system is evacuated, charged and tested in both modes. We complete any required testing paperwork and meet the inspector where the city requires a permit.
Typical prices
What ADU heating and cooling costs in Pasadena
These are typical 2026 installed ranges for ADU systems in Pasadena and nearby San Gabriel Valley cities. Size, number of rooms, equipment style and the stage of construction all matter. We quote the price before we start the work.
| Job | Typical range | What is included |
|---|---|---|
| Studio ADU, single zone mini-split | $4,870 to $7,640 | One wall head, short line set, pad or wall bracket and startup |
| One bedroom ADU, two zone system | $8,340 to $12,960 | Heads in the main room and bedroom, one outdoor unit |
| Two bedroom ADU, three zone or ducted | $11,780 to $18,430 | Multi zone heads or a slim ducted unit with short duct runs |
| Title 24 testing and documentation | $389 to $867 | When the energy report calls for duct or airflow testing at final |
Price moves with construction stage (rough-in versus finished walls), line set length across the yard, condensate pumps, electrical subpanel needs, and how closely the energy report specifies equipment. Ask about current PWP or SCE heat pump rebates when funding is open. Compare other jobs in our Pasadena HVAC price guide.
ADU heating and cooling in Pasadena homes
Pasadena lots vary a lot, and that shapes the ADU system. Deep lots behind Craftsman bungalows in Bungalow Heaven and Garfield Heights leave room for a detached unit and an outdoor heat pump tucked beside it. Hillside lots in Linda Vista and San Rafael may need the outdoor unit on a wall bracket or a carefully placed pad. Garage conversions on narrow lots in South Pasadena or Alhambra often put the outdoor unit in a side yard with tight setback rules.
Electricity comes from Pasadena Water and Power inside Pasadena and from Southern California Edison in most surrounding cities. An ADU with a separate meter or its own subpanel needs its heating and cooling circuits planned with that in mind. In Altadena, many rebuilds after the Eaton Fire include new ADUs, and we approach those projects with patience and care, working with each family's builder to keep the heating and cooling simple, efficient and ready for inspection.
Related work
Often booked with ADU Heating & Cooling
Heat Pump Installation
New ducted and inverter heat pumps sized to your Pasadena home, with permits, line sets, electrical and duct checks included in the quote.
Learn moreAttic Insulation
Air sealing first, then blown-in insulation to the right depth, so your ceilings stop radiating attic heat into the rooms.
Learn moreSmart Thermostat Installation
Smart thermostats installed with a proper C-wire and the right heat pump or two-stage settings, tested in every mode.
Learn moreWhere we do ADU Heating & Cooling
Our technicians handle this work all over Pasadena and the surrounding San Gabriel Valley. A few of the places we cover:
Questions
ADU Heating & Cooling questions from Pasadena homeowners
It depends on insulation, windows and sun exposure, but many well built 600 square foot ADUs land between 9,000 and 15,000 BTU of cooling. A garage conversion with large west facing glass may need more. We run a load calculation from the actual plans or framing rather than guessing from square footage, which avoids an oversized unit that short cycles.
Technically it is sometimes possible for an attached junior unit, but it rarely works well and can complicate permits. A detached ADU almost always needs its own system. A separate heat pump gives the occupant their own thermostat, keeps utility use easier to track, and avoids long duct runs that lose heat and cooling on the way across the yard.
Yes. New ADUs must meet California's Title 24 energy rules, and the energy compliance report filed with your plans lists the heating and cooling system and its efficiency. Some reports require duct leakage or airflow testing. We match equipment to that report and handle the testing so the final inspection goes smoothly.
As early as possible, ideally before plans go to plan check so the energy report reflects the real system. At the latest, the HVAC contractor should be on site at rough framing, before insulation and drywall, to run line sets and condensate drains inside walls. Retrofitting after drywall is possible but adds cost and exterior line set covers.
For nearly every ADU here, yes. Pasadena winters are mild, and a heat pump handles both heating and cooling efficiently from one unit. It avoids running a gas line across the yard and fits well with all electric designs encouraged under current energy rules. For a very small studio, a single zone mini-split is often all that is needed.
Need heat or cooling back today?
Call our Pasadena line any hour. A person answers, asks a few questions about the system, and gives you an arrival window.
(626) 879-0711Answering 24 hours, 7 days