Air conditioner tonnage and the Manual S sizing window

One ton = 12,000 BTU/h. Manual S sizes a single-stage AC at 100–115% of the load, so a 1.75-ton load takes a 2-ton unit. Airflow ≈ 400 CFM per ton.

A tonnage scale from 1.5 to 3 tons. The cooling load is marked at 1.75 tons (21,000 BTU/h). A green band from 100 to 115 percent of the load (1.75 to about 2.0 tons) is the ACCA Manual S acceptable range, and anything beyond is an oversized red zone. A 2-ton unit falls inside the band and is the correct pick. One ton equals 12,000 BTU/h and airflow runs about 400 CFM per ton. — Source: ACCA Manual S / IECC R403.7.1.1

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A tonnage scale from 1.5 to 3 tons. The cooling load is marked at 1.75 tons (21,000 BTU/h). A green band from 100 to 115 percent of the load (1.75 to about 2.0 tons) is the ACCA Manual S acceptable range, and anything beyond is an oversized red zone. A 2-ton unit falls inside the band and is the correct pick. One ton equals 12,000 BTU/h and airflow runs about 400 CFM per ton.

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