Mini split vs central air, which is cheaper?

Two sources, opposite answers

Read the first and a mini split is half the price. Read the second and it is a third dearer. Both appear on reputable pages with sources attached.

They are not measuring the same thing, and that is the whole answer to this question.

What each one is counting

The DOE comparison says excluding ductwork. That is a comparison of equipment at the same cooling capacity, with the ducts taken out of the central figure.

The Fixr averages are whole installed jobs, and the two jobs are not the same size. Fixr's own zone table shows what a ductless system actually covers:

The $4,400 average sits between the one-zone and two-zone rows. That is a system cooling one or two rooms, our reading, being compared against a central system cooling the whole house.

Match the capacity, and the DOE is right

Our arithmetic, marked as ours. Fixr prices central air for a house that already has ducts at $5,050 to $10,700 for a unit between 3 and 3.5 tons, including the modifications needed to add cooling to an existing furnace.

Three tons is 36,000 BTU. On Fixr's ductless table, covering a whole house takes three to five zones, which is $5,000 to $16,500.

The bottoms are within $50 of each other. The top is $5,800 higher for ductless, our subtraction. That is the DOE's point, arriving from a completely different direction, and it is why we would not tell anyone that a mini split is simply cheaper.

And then the ducts decide it

Everything above assumes the ducts exist. If they do not, the comparison inverts, and Fixr says why: retrofitting new ducts into an existing space costs nearly three times the labor of replacing existing ducts.

That is the case the format was invented for, and This Old House names it directly: ductless suits older homes with no ductwork, and home additions.

So the decision tree is short, and it is ours:

• Ducts already in place, whole house: central air is usually the cheaper purchase, and the DOE's 30% holds.
• No ducts: the mini split wins, because the central option carries a duct retrofit the ductless one does not.
• One or two rooms, whatever the house has: the mini split wins on price, and that is what the $4,400 average is really describing.

Our mini split page has the installation figures in full, including a third average from a different Fixr guide, and our central air page does the same for the ducted side.

The running cost argument

This Old House cites the Department of Energy again: duct losses can account for more than 30% of energy consumption for air conditioning.

Our reading, marked as ours. That is the strongest argument for ductless and it is rarely stated as a number. A system with no ducts cannot lose anything through them. But the figure describes typical leaky, poorly insulated ductwork, not all ductwork, and sealing the ducts you have is far cheaper than replacing the system. Our duct cleaning page covers what work on existing ducts costs.

On incentives, This Old House cites ENERGY STAR: an efficient ductless system may qualify for a federal tax credit of up to $2,000, with state and utility programmes on top.

Our arithmetic. On the $4,400 average that credit is about 45% of the purchase. On a five-zone job at $16,500 it is about 12%. The credit matters most on exactly the small installations that already looked cheap.

A third figure, and where it comes from

This Old House's own installed range for a ductless system is $4,350 to $12,250, which it attributes to Angi. We note the attribution because we always do, and because the same publisher's heat pump comparison page uses two-year-old Angi data that its own cost page has since overtaken, as our heat pump vs furnace page sets out.

Here the Angi range brackets both Fixr figures, so nothing turns on it. It is worth knowing it is borrowed rather than measured.

This Old House also adds $1,000 or more per zone for a multi-zone system, against Fixr's $2,000 to $3,000 per additional zone. Our note: those are not the same measurement either. The $1,000 reads as equipment and the Fixr figure as installed cost, and neither page says which.

The drawbacks nobody prices

This Old House lists four, and they are worth more than another price table:

• Visible wall units, where central air hides in the ceiling.
• Filters need cleaning every few weeks, not twice a year.
• Less effective at cooling the whole home than central air, in that publisher's own words.
• Zoning is the point, so a system bought to cool one room cools one room.

Our conclusion: if a quote compares a two-zone mini split with whole-house central air and presents the price difference as the finding, the quote is not a comparison. Ask for both systems sized to the same house.

Before you decide

1. Say how many rooms must be cooled, and get both quotes for that. The published averages compare different-sized jobs.
2. Ask whether usable ducts exist. It is the single fact that flips the answer.
3. If the ducts exist but leak, price sealing them before you price replacing the system around them.
4. Ask how many outdoor units a multi-zone quote needs. Zone count drives the ductless price on both publishers' tables.
5. Check the tax credit against the quote, not against the national average. At up to $2,000 it is worth proportionally far more on a small system.