Central air conditioning — and why a heat pump usually beats it
New Hampshire pays $70 a ton. A heat pump in the same ductwork pays up to $6,250. Here is when central AC still makes sense, and when it does not.
The honest advice first
If you are about to spend money on central air conditioning in the Upper Valley, spend ten minutes considering a ducted heat pump instead. It uses the same ductwork, the same electrical service and roughly the same footprint, it cools identically — and it also heats, which means it pulls a rebate several times larger than the AC rebate and takes load off an aging oil or propane system.
New Hampshire pays $70 per ton for an ENERGY STAR central air conditioner. It pays $250–$1,250 per ton for a heat pump in the same slot. Vermont does not rebate central AC at all, but pays up to $2,200 on a ducted heat pump. The programs are telling you something.
You have a nearly new, efficient heating system you are not replacing; your electrical service cannot support a heat pump’s winter load without an upgrade you do not want to fund; or a failed condenser needs replacing this week and the rest of the system is sound. Those are real situations. Outside them, the heat pump is usually the better purchase.
What the rebates are
| New Hampshire (NHSaves) | Vermont (Efficiency Vermont) | |
|---|---|---|
| Central air conditioner | $70 per ton, ENERGY STAR certified | Not rebated |
| Window / portable AC | Room AC program available | Up to $150 |
| Ducted heat pump instead | $250–$1,250 per ton, up to $6,250 | Up to $2,200 plus income bonus |
| Smart thermostat | $85 with a qualifying heat pump | Bundled into system offers |
2026 equipment must use R-32 or R-454B refrigerant in New Hampshire; R-410A is no longer eligible for rebates.
Cooling an old house that has ducts
Most Upper Valley houses with usable ductwork are post-1970 — ranches, raised ranches, and newer construction in Grantham, Hartford and the Lebanon suburbs. In those houses central AC is straightforward: a condenser outside, an evaporator coil on the existing air handler, and a thermostat.
Two things determine whether it works well:
- Duct condition. Ducts running through an unconditioned attic or crawlspace lose 20–30% of what the system produces, and in cooling season they also pick up heat and humidity. Sealing and insulating them is cheap relative to the equipment and is the single highest-return thing you can do to an existing duct system. Duct sealing →
- Attic insulation. An uninsulated attic in August is a 130°F radiator over your ceiling. Insulating it lowers the cooling load and is separately rebated at 75–90%. Insulation →
Sizing, and why bigger is worse
An oversized air conditioner cools the air quickly, satisfies the thermostat, and shuts off before it has run long enough to pull humidity out. The result is a house that is cold and clammy — which is the usual complaint behind “the AC runs but it never feels comfortable.” Ask for a Manual J load calculation. In our climate, correctly sized units are frequently smaller than homeowners expect.
What it costs here
- Condenser and coil, existing usable ductwork: $5,500–$9,500
- With duct sealing and repairs: add $1,200–$3,000
- New ductwork in an old house: add $8,000–$18,000
At $70 per ton, a three-ton system earns $210 in New Hampshire. That is not a number to plan around. The comparison worth running is what the same money buys as a heat pump, with a rebate an order of magnitude larger. Heat pumps →
If you have no ducts
Do not build them for cooling alone. In a house with radiators or baseboard, ductless mini splits cool far more cheaply and carry Vermont’s $475-per-head rebate on top. Ductless mini splits →
Figures checked July 2026. Rebate programs change their amounts, caps and equipment requirements during the year, and several are capped by available funding. Confirm the current offer with the program or your contractor before you sign anything.
Central air conditioning: common questions
Does Vermont rebate central air conditioning?
No. Efficiency Vermont does not offer a central AC rebate, on the reasonable view that a cold-climate heat pump does the same cooling job and also heats. Window and portable units get up to $150. If you want rebated whole-house cooling in Vermont, the path is a ducted heat pump at up to $2,200.
What does New Hampshire pay for central AC?
$70 per ton on ENERGY STAR certified equipment through NHSaves. On a typical three-ton system that is $210. A ducted heat pump in the same position earns $250–$1,250 per ton, up to $6,250 if you are replacing electric resistance heat.
Can I add central AC to a house with hot water baseboard?
Only by installing a full duct system, which in a plaster-and-lath Upper Valley house is expensive and invasive — frequently $8,000–$18,000 before the cooling equipment. Ductless mini splits are the normal answer for houses heated by radiators or baseboard, and they carry a much better rebate.
Why does my AC run constantly but the upstairs stays hot?
Usually duct leakage, an uninsulated attic, or both — and occasionally a system that was sized for the ground floor. In an Upper Valley house with ducts in the attic, expect a meaningful share of the cooling to be delivered to the attic rather than the bedrooms. Sealing the ducts and insulating the attic floor is both cheaper and better rebated than buying more tonnage.
Is an old R-410A system still worth repairing?
It can be, but understand the trajectory: R-410A is being phased down, 2026 rebates require R-32 or R-454B, and refrigerant cost for older systems will keep climbing. If a repair is a few hundred dollars, do it. If it is a compressor, price a heat pump replacement before you commit.
Compare central AC against a heat pump for your house
Same ductwork, very different rebate. We’ll run both numbers for your address.