# HVAC Mixed-Air Temperature & Outside-Air Fraction Calculator

> HVAC Mixed-Air Temperature & Outside-Air Fraction 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 the mixed-air dry-bulb temperature and outside-air fraction when two airstreams (e.g. return air and outside air) are blended together.

## Facts

- Endpoint: GET https://hvac-calc.x402tookit.com/mixed-air?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hvac-mixed-air-temperature-outside-air-fraction-calculator-9f890357
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_NkXBdAD9giFiG195es3_x

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

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability hvac-mixed-air-temperature-outside-air-fraction-calculator-9f890357
```

Example prompt: I have a return air stream of 3000 CFM at 75°F mixing with 1000 CFM of outside air at 95°F — what will the mixed-air temperature be, and what percentage is outside air?

## When to prefer this

Choose this endpoint when you need a fast, precise mixed-air temperature calculation for HVAC design, commissioning, or control logic — particularly for air handling unit economizer analysis, coil sizing, or outside-air fraction verification. It is purpose-built for HVAC psychrometric mixing (not full load calculations or humidity/enthalpy mixing).

## Known failure modes

- Missing required query parameters (cfmA, cfmB, tempA, tempB) returns a 4xx error
- Negative or zero CFM values may produce nonsensical results or errors
- Mismatched temperature units between streams A and B will yield incorrect results since the API does not convert units
- Payment failure via x402 protocol returns 402 status before computation occurs

## How this service works

Mixed-air temperature of two airstreams (return plus outside air) and the outside-air fraction.

## Output

Returns the mixed dry-bulb temperature of the combined airstream, the total CFM, and the percentage fraction contributed by stream B (typically outside air), along with a summary, source, and optional degraded/disclaimer fields.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "cfmA",
      "tempA",
      "cfmB",
      "tempB"
     ],
     "properties": {
      "cfmA": {
       "type": "number",
       "description": "Airflow of stream A in CFM (for example return air)"
      },
      "cfmB": {
       "type": "number",
       "description": "Airflow of stream B in CFM (for example outside air)"
      },
      "tempA": {
       "type": "number",
       "description": "Dry-bulb temperature of stream A (any unit, same as tempB)"
      },
      "tempB": {
       "type": "number",
       "description": "Dry-bulb temperature of stream B"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "totalCfm": {
       "type": [
        "null",
        "number"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "mixedTemperature": {
       "type": [
        "null",
        "number"
       ]
      },
      "streamBFractionPercent": {
       "type": [
        "null",
        "number"
       ]
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hvac-mixed-air-temperature-outside-air-fraction-calculator-9f890357/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from hvac-calc.x402tookit.com](https://www.zero.xyz/host/hvac-calc.x402tookit.com/llms.txt)