# HVAC Calculator: Psychrometrics, Coil Load, Duct Size (`vanakenj45/hvac-calculator`) Actor

Standard HVAC calculations with every step shown: psychrometric air properties from two readings, cooling/heating coil load from airflow and entering/leaving air, and round/rectangular duct sizing by friction rate. IP or SI units.

- **URL**: https://apify.com/vanakenj45/hvac-calculator.md
- **Developed by:** [Vanaken Digital](https://apify.com/vanakenj45) (community)
- **Categories:** Developer tools, AI, Other
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $2.00 / 1,000 calculations

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.

Learn more: https://docs.apify.com/actors/running/actors-in-store.md#pay-per-event

## What's an Apify Actor?

An Actor is a serverless cloud program that runs on the Apify platform. It has two run modes.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.

Apify vocabulary and the platform model are defined once, in the agent quickstart at https://apify.com/agents.md.

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.

Do not guess an integration path. Every one of them is in the agent quickstart at https://apify.com/agents.md: the Apify MCP server, Agent Skills with the Apify CLI, the JavaScript and Python clients, the REST API, and the account-free path for an agent with no human to sign in. It also carries the rule on stating cost before the first paid run.

For examples already wired to this Actor's own input schema, see the [API](#api) section below.

Each client library has reference documentation the quickstart does not restate: [JavaScript/TypeScript](https://docs.apify.com/api/client/js/docs.md) (`npm install apify-client`) and [Python](https://docs.apify.com/api/client/python/docs.md) (`pip install apify-client`).

# README

## HVAC Calculator: Psychrometrics, Coil Load, Duct Size

Standard HVAC calculations, with every step shown, in IP or SI units:

- **Psychrometrics:** a full air state (dew point, relative humidity, humidity ratio, enthalpy, specific volume, wet bulb) from any two readings, corrected for elevation.
- **Coil load:** sensible, latent and total load (MBH and tons, or kW), sensible heat ratio and condensate, from airflow plus entering and leaving air (optionally outdoor/return air mixing).
- **Duct size:** round duct diameter (with nearby standard sizes) and an equivalent rectangular size for an airflow at a friction rate, with velocity, velocity pressure and Reynolds number.

Each result lists the formulas and intermediate values (`steps`), plus notes and references, so it can be checked by hand.

### Who it is for

- Technicians, students and estimators who want quick, transparent numbers.
- Developers and AI agents that need HVAC math as a tool call instead of re-implementing it.

### Input

| Field | Required | What it does |
|---|---|---|
| `calculation` | yes | `psychrometrics`, `coil_load` or `duct_size`. |
| `parameters` | yes | That calculation's inputs (see below). Common spellings are understood, e.g. `db`/`dry_bulb`, `rh`/`relative_humidity`. Add `"units": "SI"` for metric. |

Parameters by calculation:

- Psychrometrics: `{"dry_bulb": 95, "wet_bulb": 75, "elevation": 0}`. Any two of dry bulb, wet bulb, dew point, relative humidity, humidity ratio or enthalpy.
- Coil load: `{"airflow": 10000, "entering": {"dry_bulb": 80, "wet_bulb": 67}, "leaving": {"dry_bulb": 55, "wet_bulb": 54}}`. Airflow is in CFM, or L/s with SI units.
- Duct size: `{"airflow": 1000, "friction_rate": 0.08}`. Friction rate is in in. w.c. per 100 ft, or Pa/m with SI units.

Example:

```json
{ "calculation": "psychrometrics", "parameters": { "dry_bulb": 95, "wet_bulb": 75, "elevation": 0 } }
```

### Output

One dataset item per run: `calculation`, `units`, `unit_labels`, the inputs used, the results (`state`, or loads and sizes), `steps`, `notes` and `references`.

### Pricing

**$0.002 per calculation** (pay per event). Apify platform usage is included, and Apify adds its standard run-start fee of $0.00005.

### Limitations (please read)

- **Not engineering design.** Results are textbook calculations for quick estimates and checking. They are not a stamped engineering design and do not replace a licensed engineer's judgement or local code requirements.
- **Duct sizing:** Darcy-Weisbach with the Colebrook-White friction factor and galvanized steel roughness (ε = 0.0003 ft), per ASHRAE Handbook—Fundamentals Ch. 21.
- **Psychrometrics:** uses the ASHRAE Handbook—Fundamentals (2021) psychrometric equations for moist air at the pressure for your elevation; it is meant for building HVAC conditions.

### Use it from an AI agent (MCP)

This Actor runs with Apify's default limited permissions, so it is available through Apify's MCP server.
Add it to Claude, Cursor or any MCP client with:

```
https://mcp.apify.com?tools=<publisher>/hvac-calculator
```

The agent then calls it with input like `{"calculation": "duct_size", "parameters": {"airflow": 1000, "friction_rate": 0.08}}`. Results land in the run's dataset; the MCP
server's `get-dataset-items` tool reads them.

### How it works

Pure calculation. No outside data sources or network calls are used.

# Actor input Schema

## `calculation` (type: `string`):

Which calculation to run.

## `parameters` (type: `object`):

The calculation's inputs. Psychrometrics: {"dry_bulb": 95, "wet_bulb": 75, "elevation": 0}. Coil load: {"airflow": 10000, "entering": {"dry_bulb": 80, "wet_bulb": 67}, "leaving": {"dry_bulb": 55, "wet_bulb": 54}}. Duct size: {"airflow": 1000, "friction_rate": 0.08}. Add "units": "SI" for metric. See the README for every field.

## Actor input object example

```json
{
  "calculation": "psychrometrics",
  "parameters": {
    "dry_bulb": 95,
    "wet_bulb": 75,
    "elevation": 0
  }
}
```

# Actor output Schema

## `results` (type: `string`):

The calculation result with every step, notes and references (one item per run).

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
const input = {
    "calculation": "psychrometrics",
    "parameters": {
        "dry_bulb": 95,
        "wet_bulb": 75,
        "elevation": 0
    }
};

// Run the Actor and wait for it to finish
const run = await client.actor("vanakenj45/hvac-calculator").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_input = {
    "calculation": "psychrometrics",
    "parameters": {
        "dry_bulb": 95,
        "wet_bulb": 75,
        "elevation": 0,
    },
}

# Run the Actor and wait for it to finish
run = client.actor("vanakenj45/hvac-calculator").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print(f"💾 Check your data here: https://console.apify.com/storage/datasets/{run.default_dataset_id}")
for item in client.dataset(run.default_dataset_id).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{
  "calculation": "psychrometrics",
  "parameters": {
    "dry_bulb": 95,
    "wet_bulb": 75,
    "elevation": 0
  }
}' |
apify call vanakenj45/hvac-calculator --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,vanakenj45/hvac-calculator"
        }
    }
}
```

The hosted server signs you in with OAuth on first connect, so no API token belongs in this config. Clients without OAuth support can send an `Authorization: Bearer <APIFY_API_TOKEN>` header instead, using a token from API & Integrations in Apify Console (https://console.apify.com/settings/integrations).

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/EwWmopl9gIhDQpXBg/builds/kB5ASSkQR3i5RA2bc/openapi.json