Fan-powered boxes

These drafts wait for the owner. Approve makes the rule active for every station, and it takes effect on the next score. Reject keeps the rule in the history with who decided and when. A parallel box does not send a truck when the fan or heat is on and primary air is near zero. Series can still be a real fault.

Only the owner can do that.

• Draft

  fpb.parallel.fan-on-zero-primary-ok

  Do not truck a parallel box when the fan is on and primary air is near zero

  Parallel fan-powered box. The airflow sensor sits upstream of the fan. Fan on with airflow near zero while the primary damper is shut is not a fault. Do not send a P1 truck for fan on with zero supply flow.

  Approving this rule stops a truck for that pattern on the next score. It applies to every station.

  Only the owner can do that.

• Draft

  fpb.parallel.heat-on-zero-primary-ok

  Do not truck a parallel box when heat is on and primary air is near zero

  Parallel fan-powered box. Heat on with airflow near zero is the same upstream reading. The primary damper can be shut. Do not send a P1 truck for heat on with airflow near zero.

  Approving this rule stops a truck for that pattern on the next score. It applies to every station.

  Only the owner can do that.

• Draft

  fpb.series.fan-on-zero-flow

  A series box can still truck when the fan or heat is on and airflow is near zero

  Series fan-powered box. The fan sits in the airstream with the primary air. Fan on with near-zero flow and heat on with near-zero flow can still be real faults. Keep the truck for fan on with zero supply flow and heat on with airflow near zero.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  Only the owner can do that.

• Draft

  fpb.arrangement.unknown-hold

  Hold the truck until the site says series, parallel, or mixed

  Arrangement is still unknown, or the site said mixed and this box has no override. Do not send a P1 for fan on with zero supply flow or heat on with airflow near zero. Ask Learn whether the boxes are series, parallel, or mixed.

  Approving this rule stops a truck for that pattern on the next score. It applies to every station.

  Only the owner can do that.

From public catalogs

Fleet SpecRule drafts from the Open-FDD cookbook. A G36 label is the family name only. The reason cites Open-FDD. Approve on the card makes that rule active for the whole fleet, and it takes effect on the next score. Reject retires it and keeps who decided and when. Empty equipment stays empty. 31 drafts. Page size 25.

• Open-FDD Rule Cookbook
• Open-FDD Public Taxonomy
• Open-FDD Pandas Cookbook
• ASHRAE G36 AFDD family names (alignment only) — Used only for FC#1–15 family name alignment; SpecRule reason text cites Open-FDD, not paraphrased G36 equations.
• NIST ZandrEA (taxonomy skim only) — Framework primer only; no ZandrEA rule text invented.

• Draft

  openfdd.ahu.fc1-duct-static-low

  Duct static short at full fan

  Fan is floored and duct static still sits below its setpoint. That is usually a belt, bad VFD, open door, busted duct, or a pressure sensor that is lying — send a tech to the unit, do not chase it from the BAS alone.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme duct-static-short-at-full-fan · AHU, RTU · fan-cmd, duct-static-pressure, duct-static-pressure-sp · P1

  Open-FDD FC1 · source · G36 AFDD FC#1 (duct static too low at full fan speed) — family name only; cite Open-FDD FC1 for rule text.

  Only the owner can do that.

• Draft

  openfdd.ahu.cmd1-fan-cmd-status-disagree

  Fan command vs status disagree

  The fan is commanded one way and proven status says the other. Treat it as a real start/stop or proof problem — overload, belt, starter, or bad status — until someone is on the roof or at the starter.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme fan-cmd-sts-disagreement · AHU, RTU, EF · fan-cmd, fan-status · P1

  Open-FDD CMD-1 · source

  Only the owner can do that.

• Draft

  openfdd.ahu.ducthi-duct-static-high

  Duct static running high vs SP

  Duct static is riding well above setpoint. Look for closed fire/smoke dampers, stuck VAV boxes, a bad static sensor, or a fan that will not unload before rewriting the setpoint.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme duct-static-high · AHU, RTU · duct-static-pressure, duct-static-pressure-sp · P2

  Open-FDD AHU-DUCTHI · source

  Only the owner can do that.

• Draft

  openfdd.ahu.fc7-sat-low-full-heat

  SAT low with heating floored

  Heating is commanded near full and discharge air still will not meet SAT setpoint. That is a coil, valve, HW plant, or steam/HW feed problem — send a tech, not a setpoint bump.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme heating-capacity-short · AHU, RTU, MAU · discharge-air-temp, discharge-air-temp-sp, heating-valve, fan-cmd · P1

  Open-FDD FC7 · source · G36 AFDD FC#7

  Only the owner can do that.

• Draft

  openfdd.ahu.fc13-sat-high-full-cool

  SAT high with cooling floored

  Cooling is floored and discharge air is still above SAT setpoint. Suspect low refrigerant, dirty coil, stuck valve, low CHW, or failing stage — truck work, not a BAS comfort tweak.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme cooling-capacity-short · AHU, RTU, DOAS · discharge-air-temp, discharge-air-temp-sp, cooling-valve, outside-air-damper · P1

  Open-FDD FC13 · source · G36 AFDD FC#13

  Only the owner can do that.

• Draft

  openfdd.ahu.fc5-sat-cold-while-heating

  SAT colder than mix while heat commanded

  Heat is on but discharge is not warmer than mixed air the way a working coil should be. Check heating valve/actuator, HW to the coil, and the coil itself before touching setpoints.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme heating-not-delivering · AHU, RTU · discharge-air-temp, mixed-air-temp, heating-valve, fan-cmd · P1

  Open-FDD FC5 · source · G36 AFDD FC#5

  Only the owner can do that.

• Draft

  openfdd.ahu.vlv1-cooling-valve-leak

  Cooling valve leaking when closed

  Cooling valve shows closed but discharge is still colder than it should be versus setpoint or mixed air. Likely a leaking or stuck valve/actuator — send mechanical to stroke and isolate.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme stuck-or-leaking-cooling-valve · AHU, RTU · cooling-valve, discharge-air-temp, discharge-air-temp-sp, mixed-air-temp, fan-cmd · P2

  Open-FDD VLV-1 · source

  Only the owner can do that.

• Draft

  openfdd.ahu.dmp1-oa-damper-leak

  OA damper leaking when commanded shut

  OA damper is commanded near closed but mixed air still tracks outdoor air. Damper blades, seals, or actuator linkage — mechanical fix.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme oa-damper-leakage · AHU, RTU, DOAS · outside-air-damper, mixed-air-temp, outside-air-temp · P2

  Open-FDD DMP-1 · source

  Only the owner can do that.

• Draft

  openfdd.ahu.econ1-economizer-stuck-closed

  Economizer stuck closed in free-cool weather

  Fan is on, outdoor air looks good for free cooling, and the OA damper stays shut. Check stuck damper, failed actuator, or linkage before blaming the economizer enable program.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme economizer-stuck-closed · AHU, RTU · fan-cmd, outside-air-damper, outside-air-temp · P2

  Open-FDD ECON-1 · source

  Only the owner can do that.

• Draft

  openfdd.ahu.econ6-economizing-in-freeze-weather

  OA damper open in freezing weather

  Outdoor air is in freeze territory and the OA damper is still open past minimum. Coil freeze risk — get someone on the unit or close it from a safe override after confirming freeze stats and coil status.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme freeze-risk-oa-open · AHU, RTU, MAU · outside-air-damper, web-outside-air-temp, outside-air-temp · P1

  Open-FDD ECON-6 · source

  Only the owner can do that.

• Draft

  openfdd.ahu.fc14-cooling-coil-delta-when-inactive

  Cooling coil dropping temp while inactive

  The cooling coil shows a real temperature drop while cooling should be off. Leaking CHW valve or stuck actuator until proven otherwise.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme inactive-cooling-coil-delta · AHU · cooling-coil-entering-temp, cooling-coil-leaving-temp, cooling-valve, outside-air-damper · P2

  Open-FDD FC14 · source · G36 AFDD FC#14

  Only the owner can do that.

• Draft

  openfdd.ahu.fc15-heating-coil-delta-when-inactive

  Heating coil rising temp while inactive

  Heating coil shows a temperature rise while heat should be inactive. Leaking HW valve or stuck actuator — mechanical stroke check.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme inactive-heating-coil-delta · AHU · heating-coil-entering-temp, heating-coil-leaving-temp, cooling-valve, outside-air-damper, heating-valve · P2

  Open-FDD FC15 · source · G36 AFDD FC#15

  Only the owner can do that.

• Draft

  openfdd.vav.reheat-stuck-no-rise

  Reheat open but box leave temp not rising

  Reheat is commanded open with air moving and the box leave temp is not rising above inlet. Stuck reheat valve, failed coil, or bad actuator — send a tech to the box.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme vav-reheat-stuck · VAV, FPB · reheat-valve, vav-discharge-air-temp, vav-inlet-air-temp, zone-airflow · P2

  Open-FDD VAV-REHEAT · source

  Only the owner can do that.

• Draft

  openfdd.vav.vav4-damper-stuck-open

  VAV damper stuck full open

  Damper stays pinned near full open with air flowing. Stuck damper or failed actuator — mechanical on the box, not a comfort SP change.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme vav-damper-stuck-open · VAV · damper, zone-airflow · P2

  Open-FDD VAV-4 · source

  Only the owner can do that.

• Draft

  openfdd.vav.vav5-airflow-bias

  Airflow reading with damper nearly shut

  Flow reads meaningful CFM while the damper is nearly closed. Sensor tubing, pickup, or transducer bias until proven — do not trust that airflow for balancing calls.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme vav-airflow-sensor-bias · VAV · zone-airflow, damper · P2

  Open-FDD VAV-5 · source

  Only the owner can do that.

• Draft

  openfdd.plant.chw2-dp-low-at-max-pump

  CHW DP short with pump floored

  CHW pump is floored and differential pressure still will not make setpoint. Bypass open, strainer, bad pump, valve stuck, or DP sensor — plant mechanical, not a BAS comfort call.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme chw-dp-short-at-full-pump · CHILLER, CHW-PUMP · chw-diff-pressure, chw-diff-pressure-sp, chw-pump-cmd · P1

  Open-FDD CHW-2 · source

  Only the owner can do that.

• Draft

  openfdd.plant.chw1-low-delta-t

  Low chilled-water delta-T

  CHW pumps are on and the plant is not making a healthy supply-to-return delta-T. Look for low load with high flow, bypassing, dirty coils, or sensor issues before changing CHWS setpoint.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme chw-low-delta-t · CHILLER · chilled-water-supply-temp, chilled-water-return-temp, chw-pump-cmd · P2

  Open-FDD CHW-1 · source

  Only the owner can do that.

• Draft

  openfdd.plant.chw-noload1-chiller-no-load

  Chiller running with building load satisfied

  Chiller/plant is proven running while zones or AHU SAT look satisfied. Waste and wear — check enable logic, isolation, and whether the machine is actually needed before leaving it online.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme chiller-running-no-load · CHILLER · chiller-status, chw-pump-status, compressor-status, building-zone-load-satisfied, building-ahu-load-satisfied · P2

  Open-FDD CHW-NOLOAD-1 · source

  Only the owner can do that.

• Draft

  openfdd.plant.cw-apr1-high-tower-approach

  High CW approach at full tower fan

  Tower fan is floored and condenser water approach to wet-bulb is still high. Fill, basin, fan, or sensor problem — send mechanical to the tower.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme cooling-tower-high-approach · COOLING-TOWER, CHILLER · condenser-water-supply-temp, tower-fan-cmd, web-outside-air-wetbulb · P2

  Open-FDD CW-APR-1 · source

  Only the owner can do that.

• Draft

  openfdd.hp.hp1-discharge-cold-heating

  Heat pump leaving cold while zone is cold

  Fan is on, zone is cold, and discharge is not heating. Capacity, reversing valve, or refrigerant issue — truck before setpoint games.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme heatpump-heating-capacity-short · HEATPUMP, RTU · discharge-air-temp, zone-air-temp, fan-cmd · P1

  Open-FDD HP-1 · source

  Only the owner can do that.

• Draft

  openfdd.ahu.fc2-mat-below-envelope

  Mixed air colder than OAT/RAT mix allows

  With the fan on, mixed air is colder than the outdoor/return mix envelope allows. Bad MAT/OAT/RAT sensor, stratification, or a damper that is not where the BAS thinks — verify sensors and damper stroke.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme mixed-air-sensor-or-damper-fault · AHU · mixed-air-temp, outside-air-temp, return-air-temp, fan-cmd · P2

  Open-FDD FC2 · source · G36 AFDD FC#2

  Only the owner can do that.

• Draft

  openfdd.ahu.fc3-mat-above-envelope

  Mixed air warmer than OAT/RAT mix allows

  Mixed air is hotter than the outdoor/return mix envelope. Sensor bias or damper/recirc problem — check sensors and OA/RA damper positions on site.

  Approving this rule keeps a truck for that pattern on the next score. It applies to every station.

  mechanical · Theme mixed-air-sensor-or-damper-fault · AHU · mixed-air-temp, outside-air-temp, return-air-temp, fan-cmd · P2

  Open-FDD FC3 · source · G36 AFDD FC#3

  Only the owner can do that.

• Draft

  openfdd.ahu.sched1-unoccupied-runtime

  Fan running while unoccupied

  Fan status is on while occupancy is unoccupied. Fix the schedule, occ sensor, or override in the BAS — not a truck for a belt.

  Approving this rule makes it active for every station. It takes effect on the next score.

  controls · Theme unoccupied-equipment-runtime · AHU, RTU · occupied, fan-status · P2

  Open-FDD SCHED-1 · source

  Only the owner can do that.

• Draft

  openfdd.ahu.sched247-always-on

  Equipment essentially always on

  Proof shows the equipment is on nearly the entire window. Check schedule, enable, or stuck override in Workbench before sending a truck for a 'broken' unit.

  Approving this rule makes it active for every station. It takes effect on the next score.

  controls · Theme always-on-runtime · AHU, RTU, CHILLER, BOILER, HEATPUMP · fan-status, pump-status, chiller-status, compressor-status, fan-cmd · P2

  Open-FDD SCHED-247 · source

  Only the owner can do that.

• Draft

  openfdd.ahu.reset1-sat-reset-not-tracking

  SAT reset not tracking outdoor air

  SAT setpoint is not tracking the expected outdoor-air reset curve. Program/reset logic in the BAS — do not invent a new hard SAT SP from the truck.

  Approving this rule makes it active for every station. It takes effect on the next score.

  controls · Theme sat-reset-not-tracking · AHU · discharge-air-temp-sp, outside-air-temp, fan-cmd · P3

  Open-FDD RESET-1 · source

  Only the owner can do that.