Guide and picks
Cooling a house with no ductwork
Radiators, baseboards, a boiler in the basement: a house built to heat without air has no easy path to cooling with it.
By Sawyer V. · Published
The short answer
Do not add ducts; add machines. A house with hot-water heat or baseboards has nowhere for cooled air to travel, and retrofitting a duct network means soffits, chases and lost ceiling height. Cool the rooms you use: window units at 260 to 525 certified kWh a year each, or a ductless system at SEER2 32.0 if you need four or more rooms.
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At a glance
The picks, ranked
Tap any row to jump to the full reasoning. Prices are live from Amazon where we have them, and read “check price” where we don’t — never a number we cannot verify today.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | Best whole-house answer Hisense Mini-Split Heat Pump, 9,000 BTU SEER2 32.0 and EER2 18.35 per head, with HSPF2 11.80 heating — whole-home coverage without a single duct. | Four or more rooms, in a house you own and intend to keep | |
| 2 |  Best per-room answer GE Profile ClearView Smart Window Air Conditioner, 10,300 BTU CEER 14.7 and 525.5 certified kWh a year, installed in an afternoon and removable in ten minutes. | One to three rooms, or a house you are not staying in forever | |
| — | The last resort Whynter ARC-14S Dual Hose Portable Air Conditioner 9,500 BTU SACC from 1,300 W — the least efficient way to cool a room, and sometimes the only one available. | A room whose windows cannot take a unit at all |
Why not ducts
The retrofit that is rarely worth it
Adding a duct network to a finished house means finding routes for supply and return through a structure that has none. In practice that is boxed soffits in hallways, a chase through a closet on each floor, and lost ceiling height where the trunk runs.
It is disruptive, expensive and permanent, and at the end of it a ducted system is still less efficient than a modern ductless one, because ducts in unconditioned space lose capacity on the way. The one case where it makes sense is a gut renovation that has the walls open anyway.
This one is not a DIY job
Sequence
The order to do it in
- Fix the envelope first. Shade on west-facing glass, attic insulation and air sealing reduce what any machine has to remove. The detail is in window film and insulation for cooling.
- Cool the bedroom you sleep in. One room, one unit, immediately. Sleep quality is the thing people actually buy cooling for.
- Add the main living space. Two rooms covers most households for most of the summer.
- Count before going further. Past three rooms, price a ductless system against more window units — that comparison is in central air versus window units.
- Move air between rooms with a fan rather than buying a fourth unit. A hallway circulator is cheaper than any of these machines.
Running cost
What each route costs per season
Using certified figures at 18.34¢/kWh:
- Window unit, 10,300 BTU: 525.5 kWh, $96 a season per room.
- Window unit, 8,000 BTU: 400 kWh, $73.
- Ductless head: no single certified kWh figure applies, because output depends on how many heads run — but at EER2 18.35 against a window unit’s CEER 14.7, it removes the same heat for roughly a quarter less electricity, and it heats in winter as well.
- Portable: 1,300 W while running, which is $119 for 500 hours of operation — the format to avoid unless there is no alternative.
Old houses
Three constraints that decide the answer
- Window type. Casements and sliders will not take a standard unit at all, which pushes you toward ductless or the workarounds in casement and sliding window air conditioners.
- Electrical capacity. Houses without ducts often have older panels. Check what each circuit can carry before buying — units that fit a 15-amp circuit covers the arithmetic.
- Permission. Conservation rules, condo boards and landlords all restrict outdoor units and wall penetrations, which quietly rules ductless out for many buildings.
Say the unwelcome thing
Do not retrofit ducts to add air conditioning alone.
The cost lands in the structure rather than the equipment: soffits, chases, ceiling height and weeks of work. At the end you own a distribution system that loses capacity in unconditioned space, to serve a machine that is less efficient than the ductless alternative.
Spend the money on heads or on units in the rooms you use. SEER2 32.0 per head is the whole-house answer; 525.5 kWh a year per room is the answer for one to three rooms and for anyone not staying put.
In full
Every pick, and what is wrong with it
Published specifications only, each linked to the page it came from. Where a manufacturer publishes nothing, the row says so — we do not fill blanks in.
1. Best whole-house answer
Hisense Mini-Split Heat Pump, 9,000 BTU
Hisense · model AO-09U3T25P
SEER2 32.0 and EER2 18.35 per head, with HSPF2 11.80 heating — whole-home coverage without a single duct.
A ductless system is what central air became for houses that never had it. An outdoor compressor feeds one or more wall heads through small line sets, each head controlled separately.
SEER2 32.0 and EER2 18.35 are far beyond anything a window unit reaches, and HSPF2 11.80 with a published COP of 2.25 at 5°F means it also replaces whatever is heating those rooms now.
In a house with radiators, that second point is often what settles it: the same install that cools in August displaces oil or resistance heat in January, which is where the payback actually comes from.
What’s wrong with it
An installer, an outdoor unit, a penetration per head, and a capital cost that only makes sense if you own the house.
Running cost
Hisense does not publish a wattage for the AO-09U3T25P, so we cannot calculate what it costs to run. We are not going to estimate one. If Hisense publishes a nameplate figure, this block will show the arithmetic.
| Cooling capacity | 9,000 BTU/h |
|---|---|
| SEER2 | 32.0 |
| EER2 | 18.35 |
| HSPF2 | 11.80 |
| COP at 5 degrees F | 2.25 |
| Cold climate | Yes |
| Refrigerant | R-454B (GWP 470) |
| ENERGY STAR | Certified, and on the Most Efficient list |
| Noise | Not published in the certified dataset |
Every figure above is from ENERGY STAR Certified Mini-Split Heat Pumps dataset. Blanks are shown as “not published” rather than filled in.
2. Best per-room answer
GE Profile ClearView Smart Window Air Conditioner, 10,300 BTU
GE Profile · model PHNT10CC
CEER 14.7 and 525.5 certified kWh a year, installed in an afternoon and removable in ten minutes.
A window unit needs nothing from the building except a window. In a house with no ducts and no plans, that is the entire argument.
Certified at CEER 14.7 and 525.5 kWh a year — $96 a season at 18.34¢/kWh — for 10,300 BTU, which covers a living room or a large bedroom.
Two or three of these, in the rooms that actually get used, is frequently cheaper to own than a ductless system and always cheaper to start. The trade is one window per room and a unit to store each winter.
What’s wrong with it
One window given up per room, nothing for hallways or stairs, and noise inside the room rather than outside it.
Running cost — PHNT10CC
| Annual energy use | 525.5 kWh | ENERGY STAR certified figure |
|---|---|---|
| Annual cost | $96 | 525.5 × 18.34¢/kWh |
| Per cooling month | $24 | spread over a four-month season |
The annual figure is the certified value from the GE Appliances product page, PHNT10CC, with certified figures filed as PHNT10CCH1 in the ENERGY STAR Room Air Conditioners dataset, which models a standard cooling season rather than your actual summer. It is more useful than a nameplate wattage here, because a variable-speed compressor spends most of its life well below nameplate.
Rate: 18.34¢/kWh, the US average residential price for June 2026 (EIA Electric Power Monthly, Table 5.3). Yours will differ — swap it in: (watts ÷ 1000) × hours × your rate.
| Cooling capacity | 10,300 BTU/h |
|---|---|
| CEER | 14.7 |
| Annual energy use | 525.5 kWh/yr |
| vs federal standard | 35% less energy |
| Coverage claim | Up to 450 sq ft |
| Smart control | Built-in Wi-Fi via SmartHQ; Alexa, Google Assistant, IFTTT, Nest and Sonos |
| Condensate | Built-in pump |
| Dimensions | 12.8 H x 19.7 W x 28.0 D in |
| Weight | 80.0 lb |
| Refrigerant | R-32 |
| Installation | Straddles the windowsill |
| Support bracket | Required |
| Compressor | Variable speed |
| Noise | Not published as a dBA figure |
| ENERGY STAR | Certified; NOT on the Most Efficient list |
Every figure above is from GE Appliances product page, PHNT10CC, with certified figures filed as PHNT10CCH1 in the ENERGY STAR Room Air Conditioners dataset. Blanks are shown as “not published” rather than filled in.
Skip this one
Whynter ARC-14S Dual Hose Portable Air Conditioner
Whynter · model ARC-14S
9,500 BTU SACC from 1,300 W — the least efficient way to cool a room, and sometimes the only one available.
A portable keeps the whole machine indoors and vents heat through a hose, which is why it is the least efficient format: 9,500 BTU SACC from 1,300 W is roughly 7.3 BTU per watt-hour, against 18.35 for the ductless system above.
It earns its place only where the window genuinely cannot take a unit — a casement, a slider, a leaded light, a listed facade — and where a wall penetration is not permitted either.
If you do end up here, insist on dual hoses and seal the window kit properly; the reasoning is in single hose versus dual hose.
What’s wrong with it
Two and a half times the electricity of a ductless head for the same heat removed, plus a hose, a tank and 73 lb in the room.
Running cost — ARC-14S
| Nameplate power | 1300 W | manufacturer's published figure |
|---|---|---|
| Energy, 8-hour night | 10.40 kWh | 1300 ÷ 1000 × 8 |
| Cost per hour | 24¢ | at 18.34¢/kWh |
| Cost per 8-hour night | $1.91 | on the highest speed |
| Cost per 30 nights | $57 | 312.0 kWh |
Rate: 18.34¢/kWh, the US average residential price for June 2026 (EIA Electric Power Monthly, Table 5.3). Yours will differ — swap it in: (watts ÷ 1000) × hours × your rate.
| Marketing capacity | 14,000 BTU (ASHRAE-128) |
|---|---|
| DOE-rated capacity | 9,500 BTU SACC |
| Hoses | Dual |
| Power | 1,300 W / 11.6 A at 115 V |
| Noise | Under 51 dBA low, under 56 dBA high |
| Dehumidification | 71 pints/day |
| Refrigerant | R-32 |
| Dimensions | 16 W x 19 D x 35.5 H in |
| Weight | 73 lb |
| Manufacturer coverage claim | 500 sq ft |
| Warranty | 1 year unit, 3 years compressor |
Every figure above is from Whynter product page, ARC-14S. Blanks are shown as “not published” rather than filled in.
We are not linking a buy button for this one. If you want to look at it anyway, it is easy enough to find — but we would rather send you to something that fits your room.
Questions people actually ask
Frequently asked
How do you cool a house with no ductwork?
With machines that need no distribution: window or through-wall units in the rooms you use, or a ductless mini-split system with a head per room. Adding a duct network to a finished house is the expensive option and rarely the right one.
Is it worth adding ductwork for air conditioning?
Almost never on its own. The work is structural — soffits, chases and lost ceiling height — and a ducted system still loses capacity to ducts in unconditioned space. The exception is a renovation that has the walls open already.
How many mini-split heads do I need?
One per room you want independently controlled, which is the format's advantage over ducts. Below three or four rooms, window units are usually cheaper to buy and to own; above that, the ductless system takes over. The room-count arithmetic.
Can a portable air conditioner cool a whole house?
No. A portable cools the room it stands in, at roughly 7.3 BTU per watt-hour against 18.35 for a ductless head, and its hose and tank have to be managed. It belongs in rooms where nothing else will fit.
What about houses with radiators?
They are the classic no-duct case, and it simplifies things: the heating already works, so you are buying cooling only. A ductless system can still be worth it if it displaces expensive heating fuel in winter as well. When heating enters the sum.
Sources
Where these numbers came from
- ENERGY STAR Certified Air Source Heat Pumps dataset — SEER2 32.0, EER2 18.35, HSPF2 11.80 and COP 2.25 at 5F for the ductless system referenced here
- ENERGY STAR Certified Room Air Conditioners dataset — CEER and annual kWh for the window units referenced here
- EIA Electric Power Monthly, Table 5.3 — average residential electricity price
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