The cleanest way to heat and cool a garage, sunroom, workshop or addition is usually a ductless mini-split. It works on its own, so you don't overload your existing system or run new ducts. CASC installs Mitsubishi ductless systems sized to the space, with an outdoor unit and one or more indoor heads.
Why not just extend the existing ductwork?
Your current system was sized for the house it serves. Adding a room to it can leave both the new space and the rest of the home short on airflow.
Garages and sunrooms also gain and lose heat much faster than living spaces because of large doors, glass and thinner insulation. A duct tapped off the main trunk rarely keeps up, and the thermostat in the hallway has no idea the sunroom is hot.
Sometimes extending ducts is the right call, such as a small addition next to a main trunk on a system with capacity to spare. We'll tell you when that's true.
A simple way to think about it: if the existing system already struggles on hot afternoons, it has no spare capacity to give a new room. If it keeps up easily and a trunk line runs right past the addition, a short extension may work. We check both before recommending either.
How does a ductless mini-split work in these spaces?
A ductless mini-split is a heat pump with an outdoor unit connected by a small line set to one or more indoor heads. Each head has its own controls.
Because it heats and cools, one system covers the space year-round. Installation needs only a small opening in the wall for the line set, condensate drain and wiring, so it suits finished rooms and garages alike.
CASC installs Mitsubishi ductless systems.
Indoor heads come in a few styles. Wall-mounted heads are the most common. Ceiling cassettes sit flush in the ceiling, and some systems use a small concealed air handler with short duct runs. The style depends on the room's layout and how visible you want the equipment to be.
Which spaces is it good for?
Garages, workshops, sunrooms, enclosed porches, room additions, converted attics and backyard offices are all common fits.
Before you call, think about how you'll use the space. A workshop used on weekends, a sunroom used every evening and a home office used all day each call for different sizing and controls. Note the room's dimensions, window area, insulation and whether it has an exterior door you'll open often.
- Garage or workshop: plan for big temperature swings and the garage door opening.
- Sunroom: lots of glass means high heat gain in summer and heat loss in winter.
- Room addition: a dedicated head avoids borrowing air from the main system.
- Bonus room or converted attic: a head on its own keeps it comfortable without long duct runs.
What goes wrong with these projects?
Common mistakes are an undersized unit for a glass-heavy room, poor indoor head placement, sloppy line set routing and a condensate drain that backs up.
Portable and window units often struggle in sunrooms and garages. Sizing to the space, mounting the head where it can move air across the room, and pitching the drain correctly matter more than the label.
Outdoor unit placement matters as well. It needs a level base, clearance for airflow and service, and a spot where the line set can reach the indoor head without long, awkward runs. The condensate drain must slope away from the head, and in some layouts a small pump is needed to move the water.
Insulation and air sealing in the space affect results too. A garage with an uninsulated door will always work harder than a finished room, and we size with that in mind.
How does CASC install ductless for a space?
We look at the room's size, windows, insulation and how you'll use it, then size the system, place the heads and route the line set cleanly.
We pull required permits and register the equipment. New HVAC installs carry CASC's 10-year parts and 2-year labor warranty, with optional extended labor. On our Residential HVAC Maintenance Plan, each indoor head counts as one system.
What's the next step?
Request an estimate. Tell us about the space and how you plan to use it, and we'll recommend a system and give you written pricing.
We serve 16 cities from our North Little Rock shop. Call 501-307-1310, Monday through Sunday, 7 AM to 6 PM.
Frequently asked questions
Can a ductless system heat a garage in winter?
Yes. A ductless mini-split is a heat pump, so it heats as well as cools. Sizing accounts for the garage's insulation and door.
Can one outdoor unit serve more than one room?
Some systems connect several indoor heads to one outdoor unit. Whether that fits depends on the rooms and distances involved.
How does a mini-split count on the maintenance plan?
Each indoor head counts as one system on CASC's Residential HVAC Maintenance Plan: $189 for the first system and $99 for each additional, plus tax.
Terms on this page
Related guides
- Ductless mini-split vs extending central air For a room your central air does not reach well, like an addition, garage or bonus room, a ductless mini-split is often the cleaner fix. Extending central air can work when your system has spare capacity and ducts can reach the space. The deciding factors are your system's size, your duct layout and how the room is used.
- Get a free replacement estimate CASC gives free estimates on HVAC replacements, larger plumbing projects like water-heater installs, repipes and sewer replacements, and commercial HVAC projects. A technician visits, looks at your current equipment and home, sizes the job and walks you through options. Request yours through our contact form or call 501-307-1310.
- Fixes for the problem rooms in your home Most comfort and plumbing complaints come from specific spaces: a hot upstairs or bonus room, an addition or garage the ductwork doesn't reach, a house that feels muggy, or a slab floor hiding a leak. Each has its own causes and fixes, from airflow corrections and ductless systems to whole-home dehumidifiers and slab leak detection.
- Hot upstairs bedrooms and bonus rooms Upstairs rooms and bonus rooms run hot because heat rises, roofs bake in summer and the ductwork serving them is often long, leaky or undersized. The fix is usually airflow: duct modifications, sealing and better returns. When ducts can't deliver enough, a ductless mini-split dedicated to that room is a reliable option.
Make that space usable year-round
Get pricing on a ductless system sized to your room.
Request an estimate