# HVAC Fault Detection Rule Checker

> HVAC Fault Detection Rule Checker is a paid API for AI agents from prop.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-14).

Evaluates HVAC observations against caller-defined thresholds for temperature delta, commanded state, fan status, and electrical power to identify rule violations.

## Facts

- Endpoint: POST https://prop.halowerk.com/v1/hvac-fault-detect
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hvac-fault-detection-rule-checker-cc544b6c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_gQDUMTD5BTHUU9C833oMf

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-fault-detection-rule-checker-cc544b6c -d '<json body>'
```

Example prompt: Check these 50 HVAC readings for faults — use a minimum active temperature delta of 3°C, maximum of 20°C, and flag any idle observations drawing more than 0.5 kW; the unit was in cooling mode for most readings.

## When to prefer this

Choose this endpoint when you have structured HVAC sensor observations and want to apply your own rule thresholds programmatically, without connecting to a live building control system. It is ideal for batch auditing historical logs, validating commissioning data, or running spot checks on current readings when you already have the data extracted. It does not diagnose root cause, connect to BMS, or issue work orders.

## Known failure modes

- Observations array empty or exceeds 10,000 items — validation error
- supply_air_temperature_c or return_air_temperature_c out of -100 to 100°C range — rejection
- minimum_active_temperature_delta_c exceeds maximum_active_temperature_delta_c — logical conflict may cause unexpected results
- Missing required rule fields — 400-level error
- observation_id missing or exceeds 128 characters — schema rejection
- electrical_power_kw is negative — schema rejection

## How this service works

Applies caller-selected thresholds to supply/return temperature differences, commanded operation, fan state and electrical power. It identifies rule violations in supplied observations only; it does not connect to building controls, establish root cause, replace commissioning or authorize maintenance actions.

## Output

Returns a list of flagged observations, each identified by observation_id, with details on which rules were violated (e.g. temperature delta out of range, excessive idle power, unexpected fan or commanded state), enabling downstream triage or reporting.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "rules": {
   "type": "object",
   "required": [
    "minimum_active_temperature_delta_c",
    "maximum_active_temperature_delta_c",
    "maximum_idle_power_kw"
   ],
   "properties": {
    "maximum_idle_power_kw": {
     "type": "number",
     "maximum": 1000000,
     "minimum": 0
    },
    "maximum_active_temperature_delta_c": {
     "type": "number",
     "maximum": 200,
     "minimum": 0
    },
    "minimum_active_temperature_delta_c": {
     "type": "number",
     "maximum": 100,
     "minimum": 0
    }
   },
   "additionalProperties": false
  },
  "observations": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "observation_id",
     "mode",
     "commanded_on",
     "fan_on",
     "return_air_temperature_c",
     "supply_air_temperature_c",
     "electrical_power_kw"
    ],
    "properties": {
     "mode": {
      "enum": [
       "cooling",
       "heating",
       "idle"
      ],
      "type": "string"
     },
     "fan_on": {
      "type": "boolean"
     },
     "commanded_on": {
      "type": "boolean"
     },
     "observation_id": {
      "type": "string",
      "maxLength": 128,
      "minLength": 1
     },
     "electrical_power_kw": {
      "type": "number",
      "maximum": 1000000,
      "minimum": 0
     },
     "return_air_temperature_c": {
      "type": "number",
      "maximum": 100,
      "minimum": -100
     },
     "supply_air_temperature_c": {
      "type": "number",
      "maximum": 100,
      "minimum": -100
     }
    },
    "additionalProperties": false
   },
   "maxItems": 10000,
   "minItems": 1
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hvac-fault-detection-rule-checker-cc544b6c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from prop.halowerk.com](https://www.zero.xyz/host/prop.halowerk.com/llms.txt)