Whole-system airflow rollup: rooms to trunk and return

Enter each room’s CFM once: the planner sizes its branch duct (equal friction) and register (face velocity), then sums every room to size the supply trunk, return duct, and main return grille. 120 + 200 + 150 = 470 CFM → 12″ trunk and a 20×14 filter grille.

A two-tier flow. On top, three room input pills — Bedroom 120 CFM, Living room 200 CFM, and Kitchen 150 CFM — each splits with a downward arrow into two sized outputs: a gray branch duct (7, 8, and 7 inches) and a green supply register (10×4, 12×6, and 12×4). Dashed ticks drop from each room to a summation bus that adds every room’s airflow to 470 CFM total, about 1.2 tons. An arrow leads down into a system band where that 470 CFM total sizes three results: a 12-inch supply trunk at about 599 fpm (under the 900 limit), a 12-inch return duct, and a 20×14 filter return grille held slow at about 322 fpm. — Source: ACCA Manual D; ductSize.js + grilleSize.js composition

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A two-tier flow. On top, three room input pills — Bedroom 120 CFM, Living room 200 CFM, and Kitchen 150 CFM — each splits with a downward arrow into two sized outputs: a gray branch duct (7, 8, and 7 inches) and a green supply register (10×4, 12×6, and 12×4). Dashed ticks drop from each room to a summation bus that adds every room’s airflow to 470 CFM total, about 1.2 tons. An arrow leads down into a system band where that 470 CFM total sizes three results: a 12-inch supply trunk at about 599 fpm (under the 900 limit), a 12-inch return duct, and a 20×14 filter return grille held slow at about 322 fpm.

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    <img src="https://remodelcalculators.com/api/figure-embed/duct-system-rollup" alt="A two-tier flow. On top, three room input pills — Bedroom 120 CFM, Living room 200 CFM, and Kitchen 150 CFM — each splits with a downward arrow into two sized outputs: a gray branch duct (7, 8, and 7 inches) and a green supply register (10×4, 12×6, and 12×4). Dashed ticks drop from each room to a summation bus that adds every room’s airflow to 470 CFM total, about 1.2 tons. An arrow leads down into a system band where that 470 CFM total sizes three results: a 12-inch supply trunk at about 599 fpm (under the 900 limit), a 12-inch return duct, and a 20×14 filter return grille held slow at about 322 fpm." width="800" height="524" style="width:100%;height:auto;border:0" loading="lazy">
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    Diagram: <a href="https://remodelcalculators.com/construction-diagrams/duct-system-rollup" target="_blank" rel="noopener">Whole-system airflow rollup: rooms to trunk and return</a> — courtesy of <a href="https://remodelcalculators.com" target="_blank" rel="noopener">RemodelCalculators.com</a>
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