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HVAC Fan Affinity Laws Calculator
x402
HVAC Fan Affinity Laws Calculator is a paid API for AI agents from hvac-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Calculates new airflow (CFM), static pressure, and shaft power after a fan speed change using the fan affinity laws (flow ∝ N, pressure ∝ N², power ∝ N³).
Price / call$0.02
Success—
StatusUnknown
How this service works
Fan affinity laws: new airflow, pressure and power after a speed change (flow ~ N, pressure ~ N^2, power ~ N^3).
Output
Returns the speed ratio (N2/N1), flow ratio, pressure ratio, and power ratio, along with computed new airflow (newCfm), new static pressure (newStaticPressureInWg), and new shaft power (newPower), plus a human-readable summary and any applicable disclaimer.
Example use cases
VFD energy savings estimation
“Our air handler fan runs at 1800 RPM using 10 hp. If we install a VFD and drop it to 1440 RPM, calculate the new CFM, static pressure, and shaft power so I can estimate the energy savings.”
Fan speed increase for added cooling load
“Our current fan runs at 850 RPM, moving 3200 CFM at 0.8 in. wg. We need to bump it to 1050 RPM to handle a new load — what will the airflow and pressure be at the higher speed?”
Commissioning fan performance verification
“During commissioning I measured 4500 CFM at 1200 RPM with 2.0 in. wg static pressure and 5 hp shaft power. The design calls for 1350 RPM — use the fan affinity laws to tell me what airflow, pressure, and power I should expect at that design speed.”
Technical details
Endpoint
GEThttps://hvac-calc.x402tookit.com/fan-laws?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a fast, deterministic fan affinity law calculation given current and new fan speeds — ideal for VFD sizing, energy audits, commissioning checks, or any HVAC workflow where fan performance scaling is needed without running full simulation software.
Side effects
- Missing required rpmFrom or rpmTo parameters returns an error
- Zero or negative RPM values may produce invalid ratios
- If optional cfm, staticPressureInWg, or power are omitted, corresponding new values will be null
- Extremely large speed ratios may produce physically unrealistic results without warning
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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