Learn · Ductless basics
What is a ductless mini split system?
A ductless mini split heats and cools individual rooms without ductwork. An outdoor unit connects to one or more indoor heads through a small refrigerant line, giving you precise, room-by-room comfort with far less wasted energy.
The definition, in one breath
A ductless mini split is a heating and cooling system that conditions a room directly — no ducts required. It has two main parts: an outdoor condenser/compressor unit and one or more indoor air handlers (the wall-mounted "heads" you've seen). They're joined by a slim line set — refrigerant tubing, a power wire, and a condensate drain — that runs through a single three-inch hole in an exterior wall.
Because every mini split we install is a heat pump, the same system both cools in summer and heats in winter by reversing the flow of refrigerant. One quiet system, two seasons, room-by-room control.
How it's different from central AC
Central air pushes one temperature through a network of ducts from a single thermostat. A mini split skips the ducts entirely — each indoor head has its own thermostat and conditions its own zone. That single design choice is why ductless avoids the 20–30% of energy that ducted systems lose to leaks, and why it can keep a bonus room comfortable without overcooling the rest of the house.
When a mini split is the right call
- A room that never stays comfortable — over the garage, a sunroom, a west-facing office.
- A space with no ductwork — an older home, an addition, a casita or ADU, a converted garage.
- You want lower bills and quieter operation — variable-speed inverters sip power instead of slamming on and off.
If your whole house already has healthy ductwork and an efficient central system, a mini split may only make sense for the one problem room. We'll tell you that honestly on the estimate.
Where it goes wrong (and how a specialist prevents it)
Ductless is simple to describe and easy to install badly. The common failures: an oversized system that short-cycles and never dehumidifies, an undersized one that runs flat-out in August, a sloppy refrigerant charge that kills efficiency, or a leaky flare fitting that voids the warranty. Every one of those traces back to skipping the load calculation and the commissioning checklist — which is exactly the corner generalists cut when ductless is a sideline.
Frequently asked questions
Does a mini split need ductwork?
No. That's the whole point. A mini split needs only a small three-inch opening through an exterior wall for the refrigerant line set. There's no tearing into ceilings or building soffits — which is why it's ideal for homes, additions, and garages that were never built with ducts.
Will one outdoor unit cover my whole house?
It can. A multi-zone system runs 2–8 indoor heads off a single outdoor unit. For larger or oddly-laid-out homes we sometimes use more than one outdoor unit. We size it during a free in-home assessment so it's right the first time.
Are mini splits noisy?
The indoor heads are some of the quietest equipment in HVAC — often quieter than a refrigerator. The variable-speed inverter modulates continuously instead of cycling, so you don't get the loud on/off blast of a traditional system.
Keep reading
Written & reviewed by
Manny Pozos
Owner, The Mini Split Company
Manny Pozos founded The Mini Split Company after years of watching San Antonio homeowners get stuck with HVAC that doesn't fit their homes — older houses without ductwork, additions, garages, and rooms that never stay comfortable. He built a company that does one thing exceptionally well: ductless mini splits. A specialist in the systems he installs, he leads every job to factory spec.
The Mini Split Company
Book a free in-home estimate
Talk to a ductless-only specialist about your home. Free in-home estimates across San Antonio and the surrounding metro — honest options, no pressure.