HVAC Ductwork API
HVAC duct-sizing maths as an API, computed locally and deterministically — the duct dimensions an installer or designer sizes a system with so the air moves quietly and efficiently. The round-duct endpoint gives the round duct for an airflow at a target velocity: area = airflow ÷ velocity (CFM ÷ ft/min = ft²), then diameter = √(4·area/π) — 400 CFM at a 700 fpm trunk velocity wants about a 10.2-inch round, rounded up to the next 12-inch trade size. The velocity endpoint gives the air speed inside a duct from the airflow and its size, round or rectangular — 400 CFM through a 12 × 8 duct runs at 600 fpm, comfortably quiet, while the same air in a 10-inch round moves at 733 fpm. The equivalent endpoint gives the equivalent round diameter of a rectangular duct by the ASHRAE relation De = 1.30 · (a·b)^0.625 ÷ (a+b)^0.25, so a 12 × 8 rectangular carries the same air at the same friction as a 10.7-inch round — letting you size on a round friction chart and convert to fit the space. Everything is computed locally and deterministically, so it is instant and private. Ideal for HVAC-design and installer apps, duct-sizing and takeoff tools, building-services calculators, and trade-school aids. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 compute endpoints. For room air changes use a ventilation API; for the cooling/heating load use an HVAC API.
api.oanor.com/ductwork-api
