# Services from hvac-calc.x402tookit.com on Zero

> hvac-calc.x402tookit.com serves 7 paid API services for AI agents, indexed by Zero. Each is callable per call with payment handled by Zero.

Canonical page: https://www.zero.xyz/host/hvac-calc.x402tookit.com
Live health (JSON, refreshed every minute): https://www.zero.xyz/host/hvac-calc.x402tookit.com/health.json

## Services

- [HVAC Air Changes Per Hour (ACH) Calculator](https://www.zero.xyz/c/hvac-air-changes-per-hour-ach-calculator-244da913/llms.txt): $0.02/call via x402. Calculates air changes per hour (ACH) from airflow (CFM) and room volume, or computes the CFM needed to achieve a target ACH rate.
- [HVAC Fan Affinity Laws Calculator](https://www.zero.xyz/c/hvac-fan-affinity-laws-calculator-34de7491/llms.txt): $0.02/call via x402. 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).
- [HVAC Mixed-Air Temperature & Outside-Air Fraction Calculator](https://www.zero.xyz/c/hvac-mixed-air-temperature-outside-air-fraction-calculator-9f890357/llms.txt): $0.02/call via x402. Calculates the mixed-air dry-bulb temperature and outside-air fraction when two airstreams (e.g. return air and outside air) are blended together.
- [HVAC Sensible Heat & CFM Calculator](https://www.zero.xyz/c/hvac-sensible-heat-cfm-calculator-d46f9dac/llms.txt): $0.02/call via x402. Calculates sensible heat load in BTU/h (using 1.08 × CFM × ΔT) or the required CFM airflow for a given heat load and temperature difference
- [HVAC Duct Velocity & Velocity Pressure Calculator](https://www.zero.xyz/c/hvac-duct-velocity-velocity-pressure-calculator-b30fd5d3/llms.txt): $0.02/call via x402. Calculates air velocity (FPM) and velocity pressure (in. wg) in a round or rectangular duct from CFM, or the CFM required to achieve a given velocity.
- [HVAC Efficiency Unit Converter](https://www.zero.xyz/c/hvac-efficiency-unit-converter-5ad5c52f/llms.txt): $0.02/call via x402. Converts between HVAC efficiency ratings (EER, COP, kW/ton) and cooling capacity units (tons, BTU/h, kW).
- [HVAC Duct Equivalent Round Diameter Calculator](https://www.zero.xyz/c/hvac-duct-equivalent-round-diameter-calculator-d50e3266/llms.txt): $0.02/call via x402. Calculates the equivalent round duct diameter for a rectangular duct (same friction loss), or finds the missing rectangular side that matches a given round duct diameter.

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

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