Central AC vs Mini Split: Which Suits Your House?

Both cool a house. They distribute the cooling in fundamentally different ways, and that difference decides which suits your building.

Central: one system, ducts everywhere

An outdoor condenser, an indoor coil on an air handler or furnace, and ductwork carrying conditioned air to every room.

Advantages:

• Invisible. Registers only — no equipment in living space
• Even distribution when the ducts are well designed
• Whole-house filtration at one point
• Central humidification or ventilation can be integrated
• One thermostat, one system to maintain
• Uses ductwork you may already have

Disadvantages:

• Duct losses. Ducts in unconditioned attics and crawl spaces lose a substantial share of capacity through leakage and conduction
• One zone, typically. The whole house is conditioned to one setpoint
• Expensive to retrofit into a home without ducts
• Cycling losses on single-stage equipment

Ductless: equipment in the room

An outdoor unit connected to indoor heads by refrigerant lines through a small hole.

Advantages:

• No duct losses. Conditioned air is produced in the room it serves
• Genuine zoning. Each head has its own setpoint and schedule
• Inverter modulation — long steady runs rather than cycling
• Cheap to retrofit. No walls opened
• Heats too, efficiently

Disadvantages:

• Visible indoor units
• Per-room coverage. Closed rooms need their own head
• Cost scales with zones
• Filtration is per-head and basic
• Multiple units to maintain

How much energy do ducts waste?

This is underweighted in most comparisons.

Ductwork running through an unconditioned attic in summer is carrying cold air through a space that may be well over 120°F. Losses come from both leakage at joints and conduction through duct walls, and in poorly sealed systems the combined effect is substantial.

You paid to cool that air. Some of it never reaches a room.

Ductless has no distribution losses at all, which is a large part of why its real-world efficiency holds up better than a spec-sheet comparison suggests.

If you're keeping ducts, sealing them is frequently the highest-return spend in the whole project — often better than upgrading the equipment efficiency tier. See ductwork problems and cost.

How do you know if your ductwork is worth keeping?

The table below sends you to "central" whenever the ducts are sound — so it's worth knowing how to establish that, rather than taking a contractor's glance as the answer.

Two measurements settle it:

Static pressure. A technician puts a manometer across the air handler and reads the total external static pressure. Residential equipment is generally designed around 0.5 inches of water column, and a great many real systems measure well above that. High static pressure means the ducts can't carry the airflow — the system will underperform whatever you bolt onto it, and it's the single most useful number in the whole assessment. It takes about ten minutes.

Duct leakage. A duct blaster pressurizes the duct system and measures how much air escapes. It quantifies what you'd otherwise be guessing at.

If either test comes back poor, you have a decision — but not necessarily an expensive one. Sealing is often the highest-return spend in the project, and it's cheaper than the equipment upgrade people usually buy instead. Note that sealing means mastic or an approved sealing method, not duct tape, which famously fails on ducts within a few years.

The genuinely bad case is ducts that are both leaky and undersized, in an unconditioned space, with no practical route to improve. That's when ductless stops being the compromise and starts being the better system.

What does each one cost?

Ranges, since site conditions dominate:

The comparison flips entirely on that second row. With ducts in place, central is usually the better value because the expensive half of the system is already paid for. Without them, the cost of creating a duct path is what makes ductless the obvious answer in a finished home.

Run your own figures in the heat pump cost calculator and get local quotes — regional labour rates move these more than equipment choice does.

What electrical does each need?

Frequently omitted from the quote, and occasionally the deciding cost.

Central typically needs two circuits: a 240 V circuit for the outdoor condenser, and a circuit for the indoor air handler or furnace. If there are electric backup heat strips, those are a third and much larger load — often the biggest single circuit in the house.

Ductless needs one circuit per outdoor unit. On a multi-zone system, the indoor heads are usually powered from the outdoor unit over the interconnecting cable, so several zones still means one circuit. Several separate single-zone systems, however, means several circuits — which is where panel space runs out.

In both cases the breaker comes from the equipment nameplate: MCA sets the conductor, MOCP caps the breaker, and NEC 440.14 requires a disconnect within sight of the outdoor unit.

If your panel is tight, this is worth checking before you choose an approach — run a load calculation. A multi-zone ductless system on one circuit can be the answer in a house that couldn't accommodate a central system with heat strips.

What's the maintenance difference?

Central is simpler; ductless is lighter but more frequent.

Central: one filter to change every one to three months, one annual service visit, one set of equipment. Note that routine duct cleaning is not the recurring necessity it's marketed as — sealing is what your ducts actually need.

Ductless: the indoor filters are washable mesh and want rinsing roughly monthly in season — per head. Coils and blower wheels need periodic cleaning, and a neglected head develops the musty smell people describe as "dirty sock", which is biofilm on the evaporator rather than a fault.

The cost consequence appears at service time: a technician servicing a five-head system is doing five indoor units, and it's priced accordingly. A two-zone system is a modest annual cost; a six-zone system is not.

Which system zones better, central or mini split?

Central: typically one zone. The thermostat's room is correct and everything else is approximately correct. Zoned central systems exist, using motorized dampers, but they add cost and complexity and are frequently done poorly.

Ductless: zoning is inherent. Every head is its own zone. Heat the bedroom overnight and leave the guest room alone.

For homes with real load differences — a sunny west room, a cold north bedroom, an unused upstairs — this is a comfort difference, not just an efficiency one.

Should I get central air or a mini split?

Can you combine central air and mini splits?

Often the best answer isn't either extreme:

Keep the central system for the main floor, and add a single-zone mini split for the problem area — the bonus room over the garage, the converted attic, the addition the ducts never properly reached.

This solves the specific problem for a fraction of what re-ducting or upsizing the central system would cost, and it leaves a working system alone.

Similarly, for a ductless whole-house design: one head for the open-plan living area plus one compact ducted air handler serving the bedrooms is usually cheaper than five wall heads, and it removes the visible units from the bedrooms. See single zone vs multi zone mini split.

Both should be heat pumps

Whichever distribution you choose, price the heat pump version. The equipment overlaps almost entirely with a cooling-only system, the installation labor is nearly identical, and you gain efficient heating.

Mini splits are heat pumps by default. Central systems have to be specified that way — see central AC installation cost and heat pump vs air conditioner.

Where to go next

• Ductless vs central heat pump
• Do heat pumps need ductwork?
• Mini split installation cost
• Whole house fan
• Run the numbers: electricity cost calculator

More in our heating and cooling guides.