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GET
/
api
/
fcus
/
{fcuId}
Get FCU status
curl --request GET \
  --url http://aris.local/api/fcus/{fcuId} \
  --header 'Authorization: Bearer <token>'
{
  "fcuId": "fcu_01a9",
  "friendlyName": "Living Room FCU",
  "mode": "heat",
  "fanPercent": 60,
  "roomTempC": 22.5,
  "rhPercent": 46,
  "supplyTempC": 38.2,
  "returnTempC": 33.7,
  "activeFaults": [],
  "filterLastChangedTs": "2025-03-12T09:14:00Z"
}

Authorizations

​
Authorization
string
header
required

Session token or API token

Path Parameters

​
fcuId
string
required

Response

FCU status

A Fan Coil Unit (FCU) is an active, powered terminal that delivers heating, cooling, and (where supported) dehumidification to a zone. FCUs use forced convection — a fan moving air across a water coil — to condition the room.

FCUs receive airflow and mode commands from the Aris Brain and apply local safety logic for comfort and protection (cold-blow prevention, condensation protection, fan-ramp behavior). The reported mode may differ from the commanded mode due to these local safety adjustments.

​
fcuId
string

Unique identifier for the FCU.

Example:

"fcu_01a9"

​
friendlyName
string

Human-readable name for the FCU (e.g., "Living Room FCU").

Example:

"Living Room FCU"

​
mode
enum<string>

Resolved operating state of the FCU after applying local safety and protection logic. This may differ from the commanded mode due to cold-blow prevention, condensation protection, or other safety measures.

  • heat: FCU is actively heating
  • cool: FCU is actively cooling
  • idle: FCU is not actively conditioning
  • inhibit: FCU operation is inhibited by local safety logic
Available options:
heat,
cool,
idle,
inhibit
Example:

"heat"

​
fanPercent
integer

Current airflow level expressed as a normalized percentage (0-100%). FCUs with discrete speed steps (e.g., low/medium/high) map those steps into percentage values: Low = 1-33%, Medium = 34-66%, High = 67-100%.

Required range: 0 <= x <= 100
Example:

60

​
roomTempC
number

Local air temperature measured at the FCU (in Celsius). May contribute to zone temperature resolution when multiple sensors are present.

Example:

22.5

​
rhPercent
number

Local relative humidity measured at the FCU (if equipped with humidity sensor).

Example:

46

​
supplyTempC
number

Temperature of the water entering the FCU coil (system supply), in Celsius.

Example:

38.2

​
returnTempC
number

Temperature of the water leaving the FCU coil (system return), in Celsius.

Example:

33.7

​
activeFaults
string[]

List of currently active fault codes for this FCU (e.g., ["F010", "F011"]). F010 indicates an airflow fault. Empty array means no active faults.

Example:
[]
​
filterLastChangedTs
string<date-time>

Timestamp of the most recent filter replacement (ISO 8601). Used for maintenance reminders and tracking filter life.

Example:

"2025-03-12T09:14:00Z"