What size AC for Easton, MD? 3 tons for 2,000 sq ft

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

3 tons central AC or heat pump, about 34,300 BTU/hr of load

The 20 BTU per square foot chart would put in 3.5 tons, about 23% 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 3 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 701 square feet in this climate. For a single room, size by the room: 17.1 BTU/hr per square foot.

The climate it is sized for

Climate from NOAA's 1991 to 2020 normals at Royal Oak 2 Ssw (7.7 mi away). Jul is the hottest month, averaging a high of 88.1°F and a low of 70.1°F, with about 32 days a year at 90°F or more. That gives a design temperature of 93°F against 75°F inside.

What it costs to run

About 2,172 kWh a year at SEER2 14.3, or roughly $463 at Maryland's average residential rate of 21.31¢ per kWh. Cooling runs 5 months of the year here.

What drives the load in Easton

Of the 34,300 BTU/hr, 12,960 comes through walls, roof and windows on a 93°F afternoon (38%), 13,000 is sun on the house (38%), 2,120 is four people and their appliances, and 6,200 is moisture the coil has to wring out of Easton's summer air (18%).

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 28,080 BTU/hr before the moisture allowance.

Other house sizes in Easton

Single rooms with a window or mini-split unit: a 150 sq ft bedroom needs about 2,600 BTU/hr; a 350 sq ft living room needs about 6,000 BTU/hr; a 600 sq ft open plan kitchen and family room needs about 10,300 BTU/hr.

Month by month in Easton

Jul alone uses 30% of the year's cooling energy. The unit runs the equivalent of 907 hours a year at full output.

Easton against nearby cities

Of 23 Maryland cities here, Easton has the 9th highest cooling load. The range runs from Westminster at 28,000 BTU/hr to Baltimore at 39,300.

Where Easton's weather numbers come from

The nearest NOAA station with full 1991 to 2020 normals is Royal Oak 2 Ssw, 7.7 miles from the center of Easton at 10 ft above sea level. That is close enough that the station's summers are Easton's summers.

No other city in this set uses Royal Oak 2 Ssw, so this sizing is Easton's alone.

The sun over Easton in late July

At 38.78°N, the noon sun on 21 July stands 71.6° above the horizon over Easton and the day runs 14 h 19 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. Shorter days give the house a longer night to shed the day's heat.

17,381 people live in Easton, the 17th largest of the 23 Maryland cities sized on this site. Coordinates used: 38.7763, -76.0705.

Easton AC sizing questions