Traverse equipment chains

Equipment chains

Buildings distribute conditioned air, hot water, and other media through chains of equipment:

HIU → AHU → VAV → Zone

The upstream and downstream fields let you follow these chains without knowing their depth.

Upstream: “What feeds this?”

Start from an endpoint (a zone or terminal unit) and trace back to the source.

From a zone

{
  zone(siteId: "your-site-id", name: "Library") {
    name
    upstream {
      name
      type
    }
  }
}

Result: TW01-LBR-RPC-01 → TW01-XX-AHU-001 → Tower East HIU System, the full supply chain.

From a piece of equipment

{
  equipment(siteId: "your-site-id", id: "TW01-LBR-RPC-01") {
    name
    upstream {
      name
      type
      points(is: "Temperature_Sensor") {
        type
        timeseriesId
      }
    }
  }
}

This finds the upstream equipment and their temperature sensors. It is useful for diagnosing whether a comfort problem is local or upstream.

Downstream: “What does this feed?”

Start from a source and find everything it feeds.

From an HIU

{
  equipment(siteId: "your-site-id", name: "Tower East HIU System") {
    name
    downstream {
      name
      type
    }
  }
}

Result: all AHUs, VAVs, and zones the HIU feeds. Useful for understanding the blast radius of an HIU failure.

From an AHU

{
  equipment(siteId: "your-site-id", id: "TE01-XX-AHU-001") {
    name
    downstream(is: "HVAC_Zone") {
      name
    }
  }
}

Returns every zone served by TE01-XX-AHU-001, regardless of how many VAVs are in between.

Combining traversal with type filters

Root cause analysis

A zone is too warm. Is the problem local (VAV) or upstream (AHU or HIU)?

{
  zone(siteId: "your-site-id", name: "Library") {
    points(is: "Zone_Air_Temperature_Sensor") {
      timeseriesId
    }
    upstream {
      name
      type
      points(is: "Temperature_Sensor") {
        type
        timeseriesId
      }
    }
  }
}

Check the response: if the zone temperature is 26°C but the AHU supply temperature is correct at 14°C, the VAV is the problem. If the supply temperature is also high, look further upstream.

Impact analysis

An HIU is going down for maintenance. What zones will be affected?

{
  equipment(siteId: "your-site-id", name: "Tower East HIU System") {
    downstream(is: "HVAC_Zone") {
      name
      points(is: "Zone_Air_Temperature_Sensor") {
        timeseriesId
      }
    }
  }
}

Traversal options

Limit depth

# Only direct feeds (1 hop)
upstream(maxDepth: 1) { ... }

# Up to 3 hops
upstream(maxDepth: 3) { ... }

Filter by medium

# Only hot water chain
upstream(medium: "HOT_WATER") { ... }

# Only air distribution chain
downstream(medium: "AIR") { ... }

Getting started

Core concepts

Guides

Traverse equipment chains

Equipment chains

Upstream: “What feeds this?”

From a zone

From a piece of equipment

Downstream: “What does this feed?”

From an HIU

From an AHU

Combining traversal with type filters

Root cause analysis

Impact analysis

Traversal options

Limit depth

Filter by medium

Next steps

Fetch historical data

Build an AI agent

​Equipment chains

​Upstream: “What feeds this?”

​From a zone

​From a piece of equipment

​Downstream: “What does this feed?”

​From an HIU

​From an AHU

​Combining traversal with type filters

​Root cause analysis

​Impact analysis

​Traversal options

​Limit depth

​Filter by medium

​Next steps

Fetch historical data

Build an AI agent

Equipment chains

Upstream: “What feeds this?”

From a zone

From a piece of equipment

Downstream: “What does this feed?”

From an HIU

From an AHU

Combining traversal with type filters

Root cause analysis

Impact analysis

Traversal options

Limit depth

Filter by medium

Next steps