DataFusion SQL FDD Cookbook

Open-FDD edge executes fault detection as DataFusion SQL against Apache Arrow historian tables. Copy-paste rules into the SQL FDD Rules tab or POST /api/fdd-rules/{id}/test-sql.

Analyst mirror: every section below has a matching implementation in the Pandas cookbook for workflows outside Open-FDD.

Platform concepts
Fault confirmation delay (default 5 minutes)
Haystack → SQL columns
Test & activate workflow
Sensor validation
Air handling units (FC1–FC15 / GL36 A–M)
VAV zones
Economizer & ventilation
Central plants
Heat pumps
Weather station
Trim & respond advisory (GL36)
Extended rule families (v2)
Extended rule families (P2)
Framework & parity docs
Debugging & windowing

Platform concepts

Term	Meaning
`telemetry_pivot`	Wide historian table: `timestamp`, `equipment_id`, FDD input columns (`oa_t`, `sat`, …)
`telemetry`	Long format (optional) — use pivot for most HVAC rules
`fault_raw`	Boolean — instantaneous fault condition (required output column)
`confirmation_seconds`	Minimum duration fault must hold before latching (API applies after SQL)

Column names come from your Haystack assignment graph, not BACnet instance numbers.

Rule template

-- confirmation_seconds: 300  (adjust in API/UI — default 5 minutes)
-- param: example_threshold = 5.0

SELECT
  timestamp,
  equipment_id,
  oa_t,
  CASE
    WHEN oa_t IS NULL THEN false
    WHEN oa_t < 40.0 OR oa_t > 110.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu-id'

Always handle NULL — missing samples must not latch faults.

Command scaling (0–1 vs 0–100 %)

Normalize in assignments, or inline:

CASE WHEN fan_cmd > 1.0 THEN fan_cmd / 100.0 ELSE fan_cmd END AS fan_norm

Fault confirmation delay (default 5 minutes)

Raw rules can flicker true for one poll cycle. Open-FDD debounces after SQL returns fault_raw.

Default: confirmation_seconds: 300 (5 minutes). Change per rule in the workbench or API:

{"confirmation_seconds": 300}

curl -s -X POST http://127.0.0.1:8080/api/fdd-rules/RULE_ID/test-sql \
  -H "Authorization: Bearer $TOKEN" \
  -H 'Content-Type: application/json' \
  -d '{"sql":"SELECT timestamp, equipment_id, ... AS fault_raw FROM telemetry_pivot","confirmation_seconds":300}'

Poll interval	`confirmation_seconds`	Approx. consecutive samples
60 s	300 (default)	~5
60 s	600	~10
300 s	900	~3

Every rule below includes -- confirmation_seconds: 300 in comments. Increase for advisory or hunting rules (e.g. FC4 PID hunting often uses 3600).

Haystack → SQL columns

Binding chain:

Driver point → Haystack point → FDD input → telemetry_pivot column

Commission drivers (BACnet / Modbus / Haystack / JSON)
Build Haystack model (equipment + points)
Assignments — map FDD inputs (guide)
Pivot exposes FDD input IDs as columns (oa_t, sat, zone_t, …)

Discover columns: SQL FDD schema picker, Plots tab, or GET /api/fdd-schema/fdd-inputs.

Haystack role	FDD input	Pivot column
OA temp sensor	`oa_t`	`oa_t`
SAT sensor	`sat`	`sat`
SAT setpoint	`sat_sp`	`sat_sp`
Zone temp	`zone_t`	`zone_t`

Replace equip:your-ahu-id with your scoped equipment ref in production.

Test & activate workflow

Save rule: POST /api/fdd-rules with review_status: draft
Test: POST /api/fdd-rules/{id}/test-sql with confirmation_seconds: 300
Integrator approves in UI
Activate: POST /api/fdd-rules/{id}/activate

Link rules in FDD Wires: driver_point → model_point → fdd_input → sql_rule → confirmation → fault_output.

Builder API for simple thresholds:

curl -s -X POST http://127.0.0.1:8080/api/fdd-rules/builder-sql \
  -H "Authorization: Bearer $TOKEN" -H 'Content-Type: application/json' \
  -d '{"input":"oa_t","operator":"range","low":40,"high":110,"equipment_id":"equip:validation"}' | jq '.sql'

Sensor validation

Data-quality faults (bounds, flatline, rate-of-change, mixing envelope). Gate with equipment state (fan on, occupied) where appropriate.

Default bounds

Tune per site in SQL literals or assignment transforms.

Sensor kind	Min	Max	Flatline tol	Max Δ/hr	Code
Zone temp (°F)	55	90	0.10	4.0	VAV-C
Supply air temp	50	110	0.15	8.0	AHU-C
Return air temp	55	95	0.10	3.0	AHU-D
Mixed air temp	40	110	0.15	6.0	AHU-D
Outdoor air temp	−40	130	0.10	12.0	BLD-B
Duct static (inH₂O)	−0.5	3.0	0.02	0.5	AHU-A
Relative humidity (%)	0	100	1.0	15.0	DC-C
CHW temp	40	90	0.10	4.0	CH-D
Hot water temp	70	200	0.15	6.0	CH-D
CO₂ (ppm, occupied)	400	1000	5.0	200	VAV-B

SV-1 — Zone temperature out of range

Code: VAV-C · confirmation_seconds: 300

SELECT timestamp, equipment_id, zone_t,
  CASE
    WHEN zone_t IS NULL THEN false
    WHEN zone_t < 55.0 OR zone_t > 90.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-vav'
  AND occ_mode = 'occupied'

SV-2 — OA temperature out of range

Code: BLD-B · confirmation_seconds: 300

SELECT timestamp, equipment_id, oa_t,
  CASE
    WHEN oa_t IS NULL THEN false
    WHEN oa_t < 40.0 OR oa_t > 110.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

SV-3 — OA humidity out of range

Code: DC-C · confirmation_seconds: 300

SELECT timestamp, equipment_id, oa_h,
  CASE
    WHEN oa_h IS NULL THEN false
    WHEN oa_h < 10.0 OR oa_h > 95.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

SV-4 — Mixing envelope (prefer over RAT-only)

When OAT, RAT, and MAT are present, use envelope checks — see FC2 and FC3.

SV-5 — Stale data (no recent samples)

Code: BLD-D · confirmation_seconds: 300

SELECT equipment_id,
  MAX(timestamp) AS last_ts,
  true AS fault_raw
FROM telemetry_pivot
GROUP BY equipment_id
HAVING MAX(timestamp) < NOW() - INTERVAL '30' MINUTE

Adapt interval syntax to your DataFusion version; test in /sql-fdd before activate.

SV-6 — Flatline & rate-of-change

Rolling flatline/spike detection is limited in edge SQL. Use confirmation_seconds with bounds rules, or run full rolling logic in the Pandas cookbook.

Air handling units

Reference: Open-FDD AHU fault conditions FC1–FC15 (GL36-inspired). Default confirmation_seconds: 300 unless noted.

Full metadata for FC1–FC15 and all P0 rules: P0 rule catalog.

Shared params (tune per site):

Param	Default	Used in
`mix_tol`	1.15 °F	FC2, FC3, FC5, FC8, FC12
`supply_tol`	1.15 °F	FC5, FC8, FC12, FC13
`ahu_min_oa_dpr`	0.0–1.0	FC4, FC6, FC8–FC15
`delta_supply_fan`	0.55 °F	FC5, FC8, FC12, FC14, FC15
`fan_on_min`	0.01	Most FC rules

FC1 — Duct static below SP at full fan (GL36 Rule A)

Field	Value
id	FC1
taxonomy	`control.loop.ahu.duct_static_low`
severity	3 · confirmation_seconds	300
required_points	`duct_static`, `duct_static_sp`, `fan_cmd`

Code: AHU-A · param: duct_static_err=0.12, fan_hi=0.87

SELECT timestamp, equipment_id, duct_static, duct_static_sp, fan_cmd,
  CASE
    WHEN duct_static IS NULL OR duct_static_sp IS NULL OR fan_cmd IS NULL THEN false
    WHEN duct_static < duct_static_sp - 0.12
     AND CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END >= 0.87 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC2 — MAT below OAT/RAT envelope (GL36 Rule B)

Code: AHU-D · confirmation_seconds: 600 · param: mix_tol=1.15

SELECT timestamp, equipment_id, mat, oat, rat, fan_cmd,
  CASE
    WHEN mat IS NULL OR oat IS NULL OR rat IS NULL OR fan_cmd IS NULL THEN false
    WHEN CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END <= 0.01 THEN false
    WHEN mat - 1.15 < LEAST(rat - 1.15, oat - 1.15) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC3 — MAT above OAT/RAT envelope (GL36 Rule C)

Code: AHU-D · confirmation_seconds: 600

SELECT timestamp, equipment_id, mat, oat, rat, fan_cmd,
  CASE
    WHEN mat IS NULL OR oat IS NULL OR rat IS NULL OR fan_cmd IS NULL THEN false
    WHEN CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END <= 0.01 THEN false
    WHEN mat - 1.15 > GREATEST(rat + 1.15, oat + 1.15) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC4 — PID hunting (operating-state oscillation)

Code: AHU-PID-HUNT · confirmation_seconds: 3600 (recommended) · param: delta_os_max=5

Counts excessive operating-mode transitions per hour (heating-only, economizer-only, economizer+mech, mech-only). High transition count indicates PID loops hunting.

Edge SQL — hourly mode-transition count via window (simplified; full resample logic in Pandas FC4):

-- confirmation_seconds: 3600
-- param: delta_os_max = 5, ahu_min_oa_dpr = 0.05

WITH base AS (
  SELECT
    timestamp,
    equipment_id,
    CASE
      WHEN htg_valve_pct > 0 AND clg_valve_pct = 0
       AND CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END > 0
       AND oa_damper_pct = 0.05 THEN 'htg'
      WHEN htg_valve_pct = 0 AND clg_valve_pct = 0
       AND CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END > 0
       AND oa_damper_pct > 0.05 THEN 'econ'
      WHEN htg_valve_pct = 0 AND clg_valve_pct > 0
       AND CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END > 0
       AND oa_damper_pct > 0.05 THEN 'econ_mech'
      WHEN htg_valve_pct = 0 AND clg_valve_pct > 0
       AND CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END > 0
       AND oa_damper_pct = 0.05 THEN 'mech'
      ELSE 'other'
    END AS os_mode
  FROM telemetry_pivot
  WHERE equipment_id = 'equip:your-ahu'
),
transitions AS (
  SELECT *,
    CASE WHEN os_mode <> LAG(os_mode) OVER (ORDER BY timestamp)
          AND LAG(os_mode) OVER (ORDER BY timestamp) IS NOT NULL
         THEN 1 ELSE 0 END AS mode_change
  FROM base
)
SELECT timestamp, equipment_id,
  CASE
    WHEN SUM(mode_change) OVER (
      ORDER BY timestamp
      RANGE BETWEEN INTERVAL '1' HOUR PRECEDING AND CURRENT ROW
    ) > 5 THEN true
    ELSE false
  END AS fault_raw
FROM transitions

Replace 0.05 with your site’s ahu_min_oa_dpr. Test window syntax in /sql-fdd — DataFusion versions differ on RANGE intervals.

FC5 — SAT cold when heating commanded (GL36 Rule D)

Code: AHU-B · confirmation_seconds: 600 · param: delta_supply_fan=0.55

SELECT timestamp, equipment_id, sat, mat, htg_valve_pct, fan_cmd,
  CASE
    WHEN sat IS NULL OR mat IS NULL OR htg_valve_pct IS NULL OR fan_cmd IS NULL THEN false
    WHEN CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END <= 0.01 THEN false
    WHEN CASE WHEN htg_valve_pct > 1.0 THEN htg_valve_pct/100.0 ELSE htg_valve_pct END <= 0.01 THEN false
    WHEN sat + 1.15 <= mat - 1.15 + 0.55 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC6 — Estimated OA fraction mismatch

Code: AHU-OA-FRAC · confirmation_seconds: 600 · param: airflow_err=0.15, oat_rat_delta_min=5.0

Requires vav_total_flow historian column (summed VAV airflow or fan AFMS).

SELECT timestamp, equipment_id, mat, oat, rat, vav_total_flow,
  htg_valve_pct, clg_valve_pct, oa_damper_pct, fan_cmd,
  CASE
    WHEN mat IS NULL OR oat IS NULL OR rat IS NULL OR vav_total_flow IS NULL THEN false
    WHEN ABS(rat - oat) < 5.0 THEN false
    WHEN ABS(oat - rat) < 0.01 THEN false
    WHEN (
      ABS(
        GREATEST((mat - rat) / NULLIF(oat - rat, 0), 0)
        - (ahu_min_cfm_design / NULLIF(vav_total_flow, 0))
      ) > 0.15
      AND ABS(rat - oat) >= 5.0
      AND (
        (CASE WHEN htg_valve_pct > 1.0 THEN htg_valve_pct/100.0 ELSE htg_valve_pct END > 0
         AND CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END > 0)
        OR
        (CASE WHEN htg_valve_pct > 1.0 THEN htg_valve_pct/100.0 ELSE htg_valve_pct END = 0
         AND CASE WHEN clg_valve_pct > 1.0 THEN clg_valve_pct/100.0 ELSE clg_valve_pct END > 0
         AND oa_damper_pct = 0.05)
      )
    ) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

Tune ahu_min_cfm_design and 0.05 (ahu_min_oa_dpr) per site.

FC7 — SAT low with full heating (GL36 Rule E)

Code: AHU-C · confirmation_seconds: 600 · param: sat_err=1.0

SELECT timestamp, equipment_id, sat, sat_sp, htg_valve_pct, fan_cmd,
  CASE
    WHEN sat IS NULL OR sat_sp IS NULL OR htg_valve_pct IS NULL OR fan_cmd IS NULL THEN false
    WHEN CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END <= 0.01 THEN false
    WHEN sat < sat_sp - 1.0
     AND CASE WHEN htg_valve_pct > 1.0 THEN htg_valve_pct/100.0 ELSE htg_valve_pct END > 0.9 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC8 — SAT above blend in economizer mode (GL36 Rule F)

Code: AHU-E · confirmation_seconds: 600 · param: ahu_min_oa_dpr=0.05

SELECT timestamp, equipment_id, sat, mat, oa_damper_pct, clg_valve_pct,
  CASE
    WHEN sat IS NULL OR mat IS NULL OR oa_damper_pct IS NULL OR clg_valve_pct IS NULL THEN false
    WHEN oa_damper_pct <= 0.05 OR clg_valve_pct >= 0.1 THEN false
    WHEN ABS(sat - 0.55 - mat) > SQRT(POWER(1.15, 2) + POWER(1.15, 2)) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC9 — OAT too warm for free cooling (GL36 Rule G)

Code: AHU-E · confirmation_seconds: 600

SELECT timestamp, equipment_id, oat, sat_sp, oa_damper_pct, clg_valve_pct,
  CASE
    WHEN oat IS NULL OR sat_sp IS NULL OR oa_damper_pct IS NULL OR clg_valve_pct IS NULL THEN false
    WHEN oa_damper_pct <= 0.05 OR clg_valve_pct >= 0.1 THEN false
    WHEN (oat - 1.15) > (sat_sp - 0.55 + 1.15) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC10 — OAT/MAT mismatch + mech cooling (GL36 Rule H)

Code: AHU-E · confirmation_seconds: 600

SELECT timestamp, equipment_id, mat, oat, oa_damper_pct, clg_valve_pct,
  CASE
    WHEN mat IS NULL OR oat IS NULL OR oa_damper_pct IS NULL OR clg_valve_pct IS NULL THEN false
    WHEN clg_valve_pct <= 0.01 OR oa_damper_pct <= 0.9 THEN false
    WHEN ABS(mat - oat) > SQRT(POWER(1.15, 2) + POWER(1.15, 2)) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC11 — OAT/MAT mismatch economizer-only (GL36 Rule I)

Code: AHU-E · confirmation_seconds: 600

SELECT timestamp, equipment_id, oat, sat_sp, oa_damper_pct, clg_valve_pct,
  CASE
    WHEN oat IS NULL OR sat_sp IS NULL OR oa_damper_pct IS NULL OR clg_valve_pct IS NULL THEN false
    WHEN clg_valve_pct <= 0.01 OR oa_damper_pct <= 0.9 THEN false
    WHEN (oat + 1.15) < (sat_sp - 0.55 - 1.15) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC12 — SAT above blend in cooling (GL36 Rule J)

Code: AHU-B · confirmation_seconds: 600

SELECT timestamp, equipment_id, sat, mat, oa_damper_pct, clg_valve_pct,
  CASE
    WHEN sat IS NULL OR mat IS NULL OR oa_damper_pct IS NULL OR clg_valve_pct IS NULL THEN false
    WHEN clg_valve_pct <= 0.01 THEN false
    WHEN (
      (sat - 1.15 - 0.55 > mat + 1.15 AND oa_damper_pct = 0.05)
      OR (sat - 1.15 - 0.55 > mat + 1.15 AND oa_damper_pct > 0.9)
    ) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

FC13 — SAT above SP at full cooling (GL36 Rule K)

Code: AHU-C · confirmation_seconds: 600 · param: sat_err=1.0

SELECT timestamp, equipment_id, sat, sat_sp, oa_damper_pct, clg_valve_pct,
  CASE
    WHEN sat IS NULL OR sat_sp IS NULL OR oa_damper_pct IS NULL OR clg_valve_pct IS NULL THEN false
    WHEN clg_valve_pct <= 0.01 THEN false
    WHEN sat > sat_sp + 1.0
     AND (oa_damper_pct = 0.05 OR oa_damper_pct > 0.9) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

Code: CH-C · confirmation_seconds: 600

SELECT timestamp, equipment_id,
  clg_coil_enter_t, clg_coil_leave_t, oa_damper_pct, htg_valve_pct, clg_valve_pct, fan_cmd,
  CASE
    WHEN clg_coil_enter_t IS NULL OR clg_coil_leave_t IS NULL THEN false
    WHEN (clg_coil_enter_t - clg_coil_leave_t) >= SQRT(POWER(1.15, 2) + POWER(1.15, 2)) + 0.55
     AND (
       (oa_damper_pct > 0.05 AND clg_valve_pct < 0.1)
       OR (htg_valve_pct > 0 AND fan_cmd > 0)
     ) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

Code: AHU-B · confirmation_seconds: 600

SELECT timestamp, equipment_id,
  htg_coil_enter_t, htg_coil_leave_t, oa_damper_pct, htg_valve_pct, clg_valve_pct, fan_cmd,
  CASE
    WHEN htg_coil_enter_t IS NULL OR htg_coil_leave_t IS NULL THEN false
    WHEN (htg_coil_enter_t - htg_coil_leave_t) >= SQRT(POWER(1.15, 2) + POWER(1.15, 2)) + 0.55
     AND (
       (oa_damper_pct > 0.05 AND clg_valve_pct < 0.1)
       OR (clg_valve_pct > 0.01 AND oa_damper_pct = 0.05)
       OR (clg_valve_pct > 0.01 AND oa_damper_pct > 0.9)
     ) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

AHU — Additional patterns

SAT deviation from setpoint

Code: SAT_DEVIATION_HIGH · confirmation_seconds: 600 · param: err=5.0

SELECT timestamp, equipment_id, sat, sat_sp,
  CASE
    WHEN sat IS NULL OR sat_sp IS NULL THEN false
    WHEN ABS(sat - sat_sp) > 5.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

Duct static pressure high

Code: DUCT_STATIC_HIGH · confirmation_seconds: 300 · param: margin=0.25

SELECT timestamp, equipment_id, duct_static, duct_static_sp,
  CASE
    WHEN duct_static IS NULL OR duct_static_sp IS NULL THEN false
    WHEN duct_static > duct_static_sp + 0.25 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

Heating and cooling simultaneous

Code: HEAT_COOL_SIMULTANEOUS · confirmation_seconds: 300

SELECT timestamp, equipment_id, htg_valve_pct, clg_valve_pct,
  CASE
    WHEN htg_valve_pct IS NULL OR clg_valve_pct IS NULL THEN false
    WHEN htg_valve_pct > 10.0 AND clg_valve_pct > 10.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

Fan off but duct still warm

Code: FAN_OFF_DUCT_WARM · confirmation_seconds: 600 · param: delta=15.0

SELECT timestamp, equipment_id, fan_cmd, duct_t, oa_t,
  CASE
    WHEN fan_cmd IS NULL OR duct_t IS NULL OR oa_t IS NULL THEN false
    WHEN fan_cmd = false AND duct_t > oa_t + 15.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

VAV zones

VAV-1 — Zone temperature comfort band

Code: ZONE_TEMP_OUT_OF_BAND · confirmation_seconds: 900 · param: lo=68, hi=76

SELECT timestamp, equipment_id, zone_t,
  CASE
    WHEN zone_t IS NULL THEN false
    WHEN zone_t < 68.0 OR zone_t > 76.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-vav'

VAV-2 — Night setback miss

Code: NIGHT_SETBACK_MISS · confirmation_seconds: 1800 · param: unocc_max=78

SELECT timestamp, equipment_id, zone_t, occ_mode,
  CASE
    WHEN zone_t IS NULL OR occ_mode IS NULL THEN false
    WHEN occ_mode = 'unoccupied' AND zone_t > 78.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-vav'

VAV-3 — Excessive reheat during warm weather

Code: VAV-REHEAT-WARM · confirmation_seconds: 300 · param: oat_cutoff=78, reheat_min=0.52

SELECT timestamp, equipment_id, oa_t, reheat_valve_pct,
  CASE
    WHEN oa_t IS NULL OR reheat_valve_pct IS NULL THEN false
    WHEN oa_t > 78.0
     AND CASE WHEN reheat_valve_pct > 1.0 THEN reheat_valve_pct/100.0 ELSE reheat_valve_pct END > 0.52 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-vav'

VAV-4 — Damper stuck at full open

Code: VAV-DPR-100 · confirmation_seconds: 900 · param: full_open=97.5

Use confirmation to approximate sustained full-open (rolling min is easier in Pandas VAV-4):

SELECT timestamp, equipment_id, damper_pct,
  CASE
    WHEN damper_pct IS NULL THEN false
    WHEN damper_pct > 97.5 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-vav'

Economizer & ventilation

ECON-1 — Economizer stuck closed

Code: ECONOMIZER_STUCK_CLOSED · confirmation_seconds: 600

SELECT timestamp, equipment_id, fan_cmd, oa_damper_pct, oa_t,
  CASE
    WHEN fan_cmd IS NULL OR oa_damper_pct IS NULL OR oa_t IS NULL THEN false
    WHEN fan_cmd = true AND oa_damper_pct < 5.0 AND oa_t > 55.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

ECON-2 — Economizing when outdoor unfavorable

Code: ECON-WHEN-SHOULDNT · confirmation_seconds: 300 · param: oat_cutoff=63, dpr_min=0.42

SELECT timestamp, equipment_id, oa_t, oa_damper_pct,
  CASE
    WHEN oa_t IS NULL OR oa_damper_pct IS NULL THEN false
    WHEN oa_t > 63.0 AND oa_damper_pct > 0.42 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

ECON-3 — Mech cooling when econ available

Code: MECH-WHEN-ECON · confirmation_seconds: 300

SELECT timestamp, equipment_id, oa_t, oa_damper_pct, clg_valve_pct,
  CASE
    WHEN oa_t IS NULL OR oa_damper_pct IS NULL OR clg_valve_pct IS NULL THEN false
    WHEN oa_t < 63.0 AND oa_damper_pct < 0.32 AND clg_valve_pct > 0.01 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

ECON-4 — Low estimated OA fraction

Code: LOW-OA-FRAC · confirmation_seconds: 600 · param: oa_min_pct=21

SELECT timestamp, equipment_id, mat, rat, oat, fan_cmd,
  CASE
    WHEN mat IS NULL OR rat IS NULL OR oat IS NULL OR fan_cmd IS NULL THEN false
    WHEN CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END <= 0.01 THEN false
    WHEN ABS(rat - oat) <= 2.2 THEN false
    WHEN ((mat - rat) / NULLIF(oat - rat, 0) * 100.0) < 21.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

ECON-5 — Preheat over-conditioning

Code: PREHEAT-WASTE · confirmation_seconds: 600 · param: excess_tol=2.2

SELECT timestamp, equipment_id, preheat_leave_t, sat_sp, oa_t, htg_valve_pct,
  CASE
    WHEN preheat_leave_t IS NULL OR sat_sp IS NULL OR oa_t IS NULL OR htg_valve_pct IS NULL THEN false
    WHEN htg_valve_pct <= 0.01 THEN false
    WHEN (
      (oa_t > sat_sp AND preheat_leave_t - oa_t > 2.2)
      OR (oa_t < sat_sp AND preheat_leave_t - sat_sp > 2.2)
    ) THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

Central plants

CHW-1 — Low chilled-water delta-T

Code: CHW-DT-001 · confirmation_seconds: 900 · param: min_dt=4.0

SELECT timestamp, equipment_id, chw_supply_t, chw_return_t, chw_pump_cmd,
  CASE
    WHEN chw_supply_t IS NULL OR chw_return_t IS NULL THEN false
    WHEN chw_pump_cmd IS NULL OR chw_pump_cmd = false THEN false
    WHEN (chw_return_t - chw_supply_t) < 4.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-chiller-plant'

CHW-2 — DP below SP at max pump speed

Code: CHW-DP-001 · confirmation_seconds: 300 · param: dp_margin=2.2, pmp_hi=0.87

SELECT timestamp, equipment_id, chw_dp, chw_dp_sp, chw_pump_cmd,
  CASE
    WHEN chw_dp IS NULL OR chw_dp_sp IS NULL OR chw_pump_cmd IS NULL THEN false
    WHEN chw_dp < chw_dp_sp - 2.2
     AND CASE WHEN chw_pump_cmd > 1.0 THEN chw_pump_cmd/100.0 ELSE chw_pump_cmd END >= 0.87 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-chiller-plant'

CHW-3 — Plant supply temp outside deadband

Code: CHW-TEMP-DB · confirmation_seconds: 300 · param: sp_band=2.2

SELECT timestamp, equipment_id, chw_supply_t, chw_supply_t_sp, chw_pump_cmd,
  CASE
    WHEN chw_supply_t IS NULL OR chw_supply_t_sp IS NULL OR chw_pump_cmd IS NULL THEN false
    WHEN chw_pump_cmd <= 0.01 THEN false
    WHEN chw_supply_t < chw_supply_t_sp - 2.2 OR chw_supply_t > chw_supply_t_sp + 2.2 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-chiller-plant'

CHW-4 — Flow high at max pump

Code: CHW-FLOW-HIGH · confirmation_seconds: 300 · param: flow_hi=1100

SELECT timestamp, equipment_id, chw_flow, chw_pump_cmd,
  CASE
    WHEN chw_flow IS NULL OR chw_pump_cmd IS NULL THEN false
    WHEN chw_flow > 1100.0
     AND CASE WHEN chw_pump_cmd > 1.0 THEN chw_pump_cmd/100.0 ELSE chw_pump_cmd END >= 0.87 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-chiller-plant'

Validate with POST /api/fdd/inject-scenario before enabling on live plant points.

Heat pumps

HP-1 — Discharge cold when heating

Code: HP-D · confirmation_seconds: 600 · param: min_sat=85, zone_cold=69

SELECT timestamp, equipment_id, sat, zone_t, fan_cmd,
  CASE
    WHEN sat IS NULL OR zone_t IS NULL OR fan_cmd IS NULL THEN false
    WHEN fan_cmd <= 0.01 THEN false
    WHEN zone_t < 69.0 AND sat < 85.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-hp'

Weather station

WX-1 — Temperature spike between readings

Code: WX-SPIKE · confirmation_seconds: 300 · param: spike_limit=16.0

Edge SQL — compare to previous sample:

SELECT timestamp, equipment_id, oa_t,
  CASE
    WHEN oa_t IS NULL THEN false
    WHEN ABS(oa_t - LAG(oa_t) OVER (ORDER BY timestamp)) > 16.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:weather-station'

WX-2 — Gust lower than sustained wind

Code: WX-GUST · confirmation_seconds: 300

SELECT timestamp, equipment_id, wind_gust, wind_speed,
  CASE
    WHEN wind_gust IS NULL OR wind_speed IS NULL THEN false
    WHEN wind_gust < wind_speed THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:weather-station'

Trim & respond advisory (GL36)

Advisory faults for sequence health — use confirmation_seconds: 1800 or higher.

TRIM-1 — Duct static trim advisory

Code: AHU-TRIM-ADV

SELECT timestamp, equipment_id, duct_static, vav_press_req_sum,
  CASE
    WHEN duct_static IS NULL OR vav_press_req_sum IS NULL THEN false
    WHEN duct_static > 0.80 AND vav_press_req_sum < 1.0 AND duct_static > 1.35 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

TRIM-2 — Chiller plant enable advisory

Code: CHW-ENABLE-ADV

SELECT timestamp, equipment_id, chw_valve_req_count,
  CASE
    WHEN chw_valve_req_count IS NULL THEN false
    WHEN chw_valve_req_count < 2 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-chiller-plant'

TRIM-3 — HWST trim advisory

Code: HW-TRIM-ADV

SELECT timestamp, equipment_id, hw_supply_t, hw_reset_req_sum,
  CASE
    WHEN hw_supply_t IS NULL OR hw_reset_req_sum IS NULL THEN false
    WHEN hw_supply_t < 120.0 AND hw_reset_req_sum > 2.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-boiler-plant'

TRIM-4 — CHW plant reset advisory

Code: CHW-RESET-ADV

SELECT timestamp, equipment_id, chw_supply_t, chw_reset_req_sum,
  CASE
    WHEN chw_supply_t IS NULL OR chw_reset_req_sum IS NULL THEN false
    WHEN chw_supply_t < 45.0 AND chw_reset_req_sum < 1.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-chiller-plant'

Extended rule families (v2)

Standards-first rules from public FDD / re-tuning literature. Each has a matching Pandas section. Metadata follows the rule schema. Use prerequisite macros inline.

RESET-1 — SAT reset not tracking outdoor air

Field	Value
taxonomy_path	`reset.ahu.sat_oa_reset_missing`
severity	2 · confirmation_seconds: 900
required_points	`sat_sp`, `oat`, `fan_status`
prerequisites	`macro.fan_proven_on`, `macro.reset_enabled`

Intent: Supply air temperature setpoint should reset with outdoor air when reset is enabled (ASHRAE GL36 / AIRCx common finding).

-- confirmation_seconds: 900
-- param: sat_reset_err_max = 3.0  (site-adjustable °F)
SELECT timestamp, equipment_id, sat_sp, oat, fan_status,
  CASE
    WHEN sat_sp IS NULL OR oat IS NULL OR fan_status IS NULL THEN false
    WHEN fan_status = false THEN false
    WHEN COALESCE(reset_enable, true) = false THEN false
    WHEN ABS(sat_sp - (52.0 + 0.25 * (oat - 65.0))) > 3.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

Validation: normal cooling day → false; fixed SAT SP on hot day → true; missing sat_sp → false.

SCHED-1 — Equipment running while unoccupied

Field	Value
taxonomy_path	`schedule.ahu.unoccupied_runtime`
severity	2 · confirmation_seconds: 1800
required_points	`fan_status`, `occ_mode`

-- confirmation_seconds: 1800
SELECT timestamp, equipment_id, fan_status, occ_mode,
  CASE
    WHEN fan_status IS NULL OR occ_mode IS NULL THEN false
    WHEN occ_mode = 'unoccupied' AND fan_status = true THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

OVR-1 — Persistent manual override

Field	Value
taxonomy_path	`override.ahu.persistent_manual`
severity	2 · confirmation_seconds: 3600
required_points	`override_active`

-- confirmation_seconds: 3600
SELECT timestamp, equipment_id, override_active,
  CASE
    WHEN override_active IS NULL THEN false
    WHEN override_active = true THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

CMD-1 — Fan command vs status mismatch

Field	Value
taxonomy_path	`command.status.ahu.fan_cmd_status`
severity	3 · confirmation_seconds: 600
required_points	`fan_cmd`, `fan_status`

-- confirmation_seconds: 600
SELECT timestamp, equipment_id, fan_cmd, fan_status,
  CASE
    WHEN fan_cmd IS NULL OR fan_status IS NULL THEN false
    WHEN (CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END >= 0.05)
     <> fan_status THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

OA-1 — Low estimated outdoor air fraction

Field	Value
taxonomy_path	`ventilation.ahu.low_oa_fraction`
severity	2 · confirmation_seconds: 900
required_points	`oa_t`, `ra_t`, `mat`, `fan_status`

-- confirmation_seconds: 900
-- param: min_oa_frac = 0.15
SELECT timestamp, equipment_id, oa_t, ra_t, mat, fan_status,
  CASE
    WHEN oa_t IS NULL OR ra_t IS NULL OR mat IS NULL OR fan_status IS NULL THEN false
    WHEN fan_status = false THEN false
    WHEN ABS(ra_t - oa_t) < 0.5 THEN false
    WHEN ((mat - ra_t) / NULLIF(oa_t - ra_t, 0)) < 0.15 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

VLV-1 — Cooling valve leakage

Field	Value
taxonomy_path	`actuator.leakage.ahu.clg_valve`
severity	2 · confirmation_seconds: 900

-- confirmation_seconds: 900
SELECT timestamp, equipment_id, clg_valve_pct, sat, sat_sp,
  CASE
    WHEN clg_valve_pct IS NULL OR sat IS NULL OR sat_sp IS NULL THEN false
    WHEN CASE WHEN clg_valve_pct > 1.0 THEN clg_valve_pct/100.0 ELSE clg_valve_pct END > 0.05 THEN false
    WHEN sat < sat_sp - 2.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

DMP-1 — OA damper leakage

Field	Value
taxonomy_path	`actuator.leakage.ahu.oa_damper`
severity	2 · confirmation_seconds: 900

-- confirmation_seconds: 900
SELECT timestamp, equipment_id, oa_damper_pct, oa_t, mat,
  CASE
    WHEN oa_damper_pct IS NULL OR oa_t IS NULL OR mat IS NULL THEN false
    WHEN CASE WHEN oa_damper_pct > 1.0 THEN oa_damper_pct/100.0 ELSE oa_damper_pct END > 0.05 THEN false
    WHEN ABS(mat - oa_t) < 2.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

VAV-5 — Airflow sensor bias

Field	Value
taxonomy_path	`terminal.vav.airflow_sensor_bias`
severity	2 · confirmation_seconds: 900

-- confirmation_seconds: 900
SELECT timestamp, equipment_id, zone_flow, damper_pct,
  CASE
    WHEN zone_flow IS NULL OR damper_pct IS NULL THEN false
    WHEN zone_flow > 50.0
     AND CASE WHEN damper_pct > 1.0 THEN damper_pct/100.0 ELSE damper_pct END < 0.10 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-vav'

PLANT-1 — CHW DP reset missing

Field	Value
taxonomy_path	`reset.plant.chw.dp_reset_missing`
severity	2 · confirmation_seconds: 900

-- confirmation_seconds: 900
SELECT timestamp, equipment_id, chw_dp_sp, chw_load_pct, chw_pump_cmd,
  CASE
    WHEN chw_dp_sp IS NULL OR chw_load_pct IS NULL OR chw_pump_cmd IS NULL THEN false
    WHEN chw_pump_cmd <= 0.01 THEN false
    WHEN chw_load_pct < 0.40 AND chw_dp_sp > 18.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-chiller-plant'

SP-HIGH — Occupied zone setpoint too high

-- SP-HIGH confirmation_seconds: 900  param: hi = 76
SELECT timestamp, equipment_id, zone_t_sp, occ_mode,
  CASE
    WHEN zone_t_sp IS NULL OR occ_mode IS NULL THEN false
    WHEN occ_mode <> 'occupied' THEN false
    WHEN zone_t_sp > 76.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot WHERE equipment_id = 'equip:your-vav';

SP-LOW — Occupied zone setpoint too low

-- SP-LOW confirmation_seconds: 900  param: lo = 68
SELECT timestamp, equipment_id, zone_t_sp, occ_mode,
  CASE
    WHEN zone_t_sp IS NULL OR occ_mode IS NULL THEN false
    WHEN occ_mode <> 'occupied' THEN false
    WHEN zone_t_sp < 68.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot WHERE equipment_id = 'equip:your-vav';

KPI-1 — Performance score (advisory)

Aggregate confirmed faults by family — see benchmark strategy.

Extended rule families (P2)

Next-priority rules from roadmap. Matching Pandas P2 sections. Metadata in P0 catalog.

VAV-6 — Reheat active when cooling available

Field	Value
taxonomy_path	`terminal.vav.reheat_with_cooling`
severity	2 · confirmation_seconds: 300
required_points	`reheat_valve_pct`, `clg_available`, `oa_t`

-- confirmation_seconds: 300
SELECT timestamp, equipment_id, reheat_valve_pct, clg_available, oa_t,
  CASE
    WHEN reheat_valve_pct IS NULL OR oa_t IS NULL THEN false
    WHEN COALESCE(clg_available, false) = false THEN false
    WHEN oa_t >= 65.0 THEN false
    WHEN CASE WHEN reheat_valve_pct > 1.0 THEN reheat_valve_pct/100.0 ELSE reheat_valve_pct END > 0.25 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-vav'

VAV-7 — Minimum airflow violation

Field	Value
taxonomy_path	`terminal.vav.min_airflow_violation`
severity	2 · confirmation_seconds: 900
required_points	`zone_flow`, `min_flow_sp`, `fan_cmd`

-- confirmation_seconds: 900
SELECT timestamp, equipment_id, zone_flow, min_flow_sp, fan_cmd,
  CASE
    WHEN zone_flow IS NULL OR min_flow_sp IS NULL OR fan_cmd IS NULL THEN false
    WHEN CASE WHEN fan_cmd > 1.0 THEN fan_cmd/100.0 ELSE fan_cmd END <= 0.01 THEN false
    WHEN zone_flow < min_flow_sp THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-vav'

TOWER-1 — Cooling tower approach too high

Field	Value
taxonomy_path	`plant.performance.tower.approach_high`
severity	2 · confirmation_seconds: 900
required_points	`tower_leaving_t`, `wb_t`, `tower_fan_cmd`

-- confirmation_seconds: 900
-- param: max_approach = 7.0  (°F, site-adjustable)
SELECT timestamp, equipment_id, tower_leaving_t, wb_t, tower_fan_cmd,
  CASE
    WHEN tower_leaving_t IS NULL OR wb_t IS NULL OR tower_fan_cmd IS NULL THEN false
    WHEN tower_fan_cmd <= 0.01 THEN false
    WHEN (tower_leaving_t - wb_t) > 7.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-cooling-tower'

CTRL-2 — Generic control loop hunting (duct static)

Field	Value
taxonomy_path	`control.loop.generic.hunting`
severity	2 · confirmation_seconds: 3600
required_points	`duct_static`, `fan_cmd`

-- confirmation_seconds: 3600
-- param: hunt_reversals = 8  (sign changes per hour)
WITH w AS (
  SELECT timestamp, equipment_id, duct_static,
    LAG(duct_static) OVER (ORDER BY timestamp) AS prev,
    CASE
      WHEN duct_static > LAG(duct_static) OVER (ORDER BY timestamp) THEN 1
      WHEN duct_static < LAG(duct_static) OVER (ORDER BY timestamp) THEN -1
      ELSE 0
    END AS dir
  FROM telemetry_pivot
  WHERE equipment_id = 'equip:your-ahu'
)
SELECT timestamp, equipment_id,
  CASE
    WHEN COUNT(CASE WHEN dir <> LAG(dir) OVER (ORDER BY timestamp) AND dir <> 0 THEN 1 END)
         OVER (ORDER BY timestamp ROWS BETWEEN 59 PRECEDING AND CURRENT ROW) > 8 THEN true
    ELSE false
  END AS fault_raw
FROM w

Simplified edge variant — use Pandas CTRL-2 for full hourly resample.

SV-7 — Wrong-units heuristic (magnitude check)

Field	Value
taxonomy_path	`sensor.quality.generic.wrong_units`
severity	2 · confirmation_seconds: 300
required_points	`oa_t` (or any bounded sensor)

-- confirmation_seconds: 300
-- Flags values implausible for °F (e.g. 750 = 0.1°C scaling error ×10)
SELECT timestamp, equipment_id, oa_t,
  CASE
    WHEN oa_t IS NULL THEN false
    WHEN oa_t > 200.0 OR oa_t < -60.0 THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

OA-2 — DCV minimum outdoor air not met

Field	Value
taxonomy_path	`ventilation.ahu.dcv_minimum_oa`
severity	2 · confirmation_seconds: 900
required_points	`oa_flow`, `oa_flow_min_sp`, `occ_mode`, `fan_status`

-- confirmation_seconds: 900
SELECT timestamp, equipment_id, oa_flow, oa_flow_min_sp, occ_mode, fan_status,
  CASE
    WHEN oa_flow IS NULL OR oa_flow_min_sp IS NULL OR occ_mode IS NULL THEN false
    WHEN fan_status = false OR occ_mode <> 'occupied' THEN false
    WHEN oa_flow < oa_flow_min_sp THEN true
    ELSE false
  END AS fault_raw
FROM telemetry_pivot
WHERE equipment_id = 'equip:your-ahu'

Framework & parity docs

Doc	Purpose
Public taxonomy	Equipment classes, rule families
Rule schema	Declarative source-of-truth
Gap matrix	Coverage vs public literature
Parity matrix	SQL ↔ Pandas audit
Roadmap	Priority-ranked expansion
Prerequisite macros	Reusable guards
Benchmark strategy	Scenarios & regression
Doc template	Per-rule documentation

Debugging & windowing

	Historian lookback	Rolling / confirmation
Set by	SQL FDD test window, validation tab, API	`confirmation_seconds` (default 300)
Typical	1–24 h for test	5 min default debounce

Debug workflow

Plots — confirm columns exist and values move
SQL FDD — run SELECT without fault_raw first
Test SQL — add fault_raw, set confirmation_seconds: 300
Validation tab — overlay faults on live trends
API — GET /api/agent/validate for historian parity

Common failures

Symptom	Check
Zero rows	Wrong `equipment_id` or empty pivot
Always false	NULL inputs; wrong column name
Always true	Missing NULL guard; threshold too tight
No faults on dashboard	Rule not activated; confirmation too long

Compare with Pandas

Export the same historian window, run the matching Pandas section, diff flagged timestamps — should align within one poll period.

Next: Pandas cookbook — duplicate rules for analyst workflows outside Open-FDD

DataFusion SQL FDD Cookbook

Table of contents

Platform concepts

Rule template

Command scaling (0–1 vs 0–100 %)

Fault confirmation delay (default 5 minutes)

Haystack → SQL columns

Test & activate workflow

Sensor validation

Default bounds

SV-1 — Zone temperature out of range

SV-2 — OA temperature out of range

SV-3 — OA humidity out of range

SV-4 — Mixing envelope (prefer over RAT-only)

SV-5 — Stale data (no recent samples)

SV-6 — Flatline & rate-of-change

Air handling units

FC1 — Duct static below SP at full fan (GL36 Rule A)

FC2 — MAT below OAT/RAT envelope (GL36 Rule B)

FC3 — MAT above OAT/RAT envelope (GL36 Rule C)

FC4 — PID hunting (operating-state oscillation)

FC5 — SAT cold when heating commanded (GL36 Rule D)

FC6 — Estimated OA fraction mismatch

FC7 — SAT low with full heating (GL36 Rule E)

FC8 — SAT above blend in economizer mode (GL36 Rule F)

FC9 — OAT too warm for free cooling (GL36 Rule G)

FC10 — OAT/MAT mismatch + mech cooling (GL36 Rule H)

FC11 — OAT/MAT mismatch economizer-only (GL36 Rule I)

FC12 — SAT above blend in cooling (GL36 Rule J)

FC13 — SAT above SP at full cooling (GL36 Rule K)

FC14 — CHW coil ΔT when inactive (GL36 Rule L)

FC15 — HW coil ΔT when inactive (GL36 Rule M)

AHU — Additional patterns

SAT deviation from setpoint

Duct static pressure high

Heating and cooling simultaneous

Fan off but duct still warm

VAV zones

VAV-1 — Zone temperature comfort band

VAV-2 — Night setback miss

VAV-3 — Excessive reheat during warm weather

VAV-4 — Damper stuck at full open

Economizer & ventilation

ECON-1 — Economizer stuck closed

ECON-2 — Economizing when outdoor unfavorable

ECON-3 — Mech cooling when econ available

ECON-4 — Low estimated OA fraction

ECON-5 — Preheat over-conditioning

Central plants

CHW-1 — Low chilled-water delta-T

CHW-2 — DP below SP at max pump speed

CHW-3 — Plant supply temp outside deadband

CHW-4 — Flow high at max pump

Heat pumps

HP-1 — Discharge cold when heating

Weather station

WX-1 — Temperature spike between readings

WX-2 — Gust lower than sustained wind

Trim & respond advisory (GL36)

TRIM-1 — Duct static trim advisory

TRIM-2 — Chiller plant enable advisory

TRIM-3 — HWST trim advisory

TRIM-4 — CHW plant reset advisory

Extended rule families (v2)

RESET-1 — SAT reset not tracking outdoor air

SCHED-1 — Equipment running while unoccupied

OVR-1 — Persistent manual override

CMD-1 — Fan command vs status mismatch

OA-1 — Low estimated outdoor air fraction

VLV-1 — Cooling valve leakage

DMP-1 — OA damper leakage

VAV-5 — Airflow sensor bias

PLANT-1 — CHW DP reset missing

SP-HIGH — Occupied zone setpoint too high

SP-LOW — Occupied zone setpoint too low

KPI-1 — Performance score (advisory)

Extended rule families (P2)

VAV-6 — Reheat active when cooling available

VAV-7 — Minimum airflow violation

TOWER-1 — Cooling tower approach too high