What size AC for Milford, CT? 2.5 tons for 2,000 sq ft

What size AC a 2,000 sq ft house in Milford needs

2.5 tons central AC or heat pump, about 28,200 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 49% more than this climate needs. An oversized unit cools the air fast, shuts off before it pulls moisture out, and leaves the house cold and clammy.

If a contractor quotes you more than 2.5 tons for an average 2,000 sq ft house here, ask to see the Manual J load calculation behind it before you sign. That works out to one ton per 853 square feet in this climate. For a single room, size by the room: 14.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Igor I Sikorsky Mem Airport (5.2 mi away). Jul is the hottest month, averaging a high of 83.4°F and a low of 67.9°F, with about 9 days a year at 90°F or more. That gives a design temperature of 88°F against 75°F inside.

What it costs to run

About 1,328 kWh a year at SEER2 14.3, or roughly $365 at Connecticut's average residential rate of 27.47¢ per kWh. Cooling runs 4 months of the year here.

What drives the load in Milford

Of the 28,200 BTU/hr, 9,360 comes through walls, roof and windows on a 88°F afternoon (33%), 13,000 is sun on the house (46%), 2,120 is four people and their appliances, and 3,700 is moisture the coil has to wring out of Milford's summer air (13%).

Sun is the biggest share here, more than heat through the walls, so shading west windows and a light roof cut the size you need more than extra insulation would. Sensible heat totals 24,480 BTU/hr before the moisture allowance.

Other house sizes in Milford

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,100 BTU/hr; a 350 sq ft living room needs about 4,900 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 8,500 BTU/hr.

Month by month in Milford

Jul alone uses 35% of the year's cooling energy. The unit runs the equivalent of 674 hours a year at full output.

Milford against nearby cities

Of 21 Connecticut cities here, Milford has the 6th highest cooling load. The range runs from Groton at 24,800 BTU/hr to Hartford at 29,000.

Where Milford's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Igor I Sikorsky Mem Airport, 5.2 miles from the center of Milford at 6 ft above sea level. That is close enough that the station's summers are Milford's summers.

2 other cities use the same station and get the same climate inputs. The closest to Milford: Shelton (7 mi away, 9.7 mi from the station), Bridgeport (7 mi away, 3.9 mi from the station). Milford is farther from the station than 1 of them.

The sun over Milford in late July

At 41.22°N, the noon sun on 21 July stands 69.2° above the horizon over Milford and the day runs 14 h 32 min from sunrise to sunset. A lower noon sun puts more of the day's heat on east and west walls than on the roof, which is why shading west glass pays off here. Long days mean the house keeps gaining heat into the evening, well after the outdoor peak.

51,004 people live in Milford, the 12th largest of the 21 Connecticut cities sized on this site. Coordinates used: 41.2236, -73.0646.

Milford AC sizing questions