Airflow heat load, air changes, duct sizing, velocity, fan laws, efficiency conversions and mixed-air temperature.
payments ON MAINNET (real money) · 7 live endpoints
| Endpoint | Price | What it answers |
|---|---|---|
GET /air-changes | $0.02 | Air changes per hour (ACH) from airflow and room volume, or the CFM needed for a target ACH. |
GET /duct-equivalent | $0.02 | Equivalent round diameter of a rectangular duct (same friction), or the second side that matches a round duct. |
GET /duct-velocity | $0.02 | Air velocity (FPM) and velocity pressure (in. wg) in a round or rectangular duct from CFM, or the CFM at a velocity. |
GET /efficiency-convert | $0.02 | Convert EER, COP and kW per ton, and tons, BTU/h and kW of cooling capacity. |
GET /fan-laws | $0.02 | Fan affinity laws: new airflow, pressure and power after a speed change (flow ~ N, pressure ~ N^2, power ~ N^3). |
GET /mixed-air | $0.02 | Mixed-air temperature of two airstreams (return plus outside air) and the outside-air fraction. |
GET /sensible-heat | $0.02 | Sensible heat from airflow and temperature difference (1.08 x CFM x dT), or the CFM needed for a heat load. |
GET /catalog returns this list as JSON. Activity hub · uptime.
Computed locally from standard HVAC rules of thumb and formulas, provided as is, with no warranty. Not a Manual J or other load calculation and not engineering advice; real systems need a qualified designer. Every paid response carries a disclaimer field.