# Fault library — Pelorus Engineering

> The 96 fault-detection rules in Pelorus Engineering's Energy Agent, one page each: what the fault means, why it matters, and what to do about it, across eight equipment families. Detector thresholds and formulas are not published. Sixteen air-side rules are aligned with ASHRAE Guideline 36 fault conditions FC01–FC16 (Guideline 36 text is not reproduced). Author: Pelorus Engineering, Brent Waluzak, P.E. (FL). Last generated 2026-09-13T02:05:39Z.

- [All rules (index)](https://learn.pelorusengineering.com/faults/)
- [Glossary](https://learn.pelorusengineering.com/faults/glossary/)
- [Readiness quiz: which of the 96 rules can run on your data](https://learn.pelorusengineering.com/faults/readiness/)
- [What your data unlocks: the 27 analyses and what each file turns on](https://learn.pelorusengineering.com/faults/what-your-data-unlocks/)
- [How to get your data: interval data, Niagara, Metasys, Tracer, Desigo, EcoStruxure, BACnet, schedule and bills, data quality](https://learn.pelorusengineering.com/faults/guides/)
- [CSV templates](https://learn.pelorusengineering.com/faults/templates/interval-template.csv)
- [How Energy Agent verifies savings: IPMVP Option C, ASHRAE Guideline 14, CV(RMSE), NMBE, TOWT baseline, confidence intervals, two worked examples](https://learn.pelorusengineering.com/faults/verified-savings/)
- [Full text of every rule](https://learn.pelorusengineering.com/faults/llms-full.txt)
- [Machine-readable rules (JSON)](https://learn.pelorusengineering.com/faults/rules.json)
- [Energy Agent](https://www.pelorusengineering.com/energy-agent/): the product that runs these rules
- [Request a demo](https://www.pelorusengineering.com/contact/?interest=energy-agent)

## Whole-building meter (11 rules)

- [MET-01 Excessive night / weekend baseload](https://learn.pelorusengineering.com/faults/meter/met-01-excessive-night-weekend-baseload/): Baseload power during unoccupied hours is higher than expected for the building's size and type.
- [MET-02 Baseload creeping up over time](https://learn.pelorusengineering.com/faults/meter/met-02-baseload-creeping-up-over-time/): The minimum nightly demand has been trending upward across the analysis window.
- [MET-03 After-hours operation](https://learn.pelorusengineering.com/faults/meter/met-03-after-hours-operation/): Building demand is well above baseload during hours the schedule says it should be off.
- [MET-04 Weekend load shape looks like a weekday](https://learn.pelorusengineering.com/faults/meter/met-04-weekend-load-shape-looks-like-a-weekday/): Saturday and Sunday demand profiles look almost identical to weekday profiles, despite no occupancy.
- [MET-05 Anomalous peak demand event](https://learn.pelorusengineering.com/faults/meter/met-05-anomalous-peak-demand-event/): A measured peak demand interval is far above what historical demand for that calendar position would predict.
- [MET-06 Weather sensitivity has changed](https://learn.pelorusengineering.com/faults/meter/met-06-weather-sensitivity-has-changed/): The building's response to outdoor temperature (kWh per degree-day) has shifted from its historical baseline.
- [MET-07 Heating + cooling fuel signature overlap](https://learn.pelorusengineering.com/faults/meter/met-07-heating-cooling-fuel-signature-overlap/): Gas (heating) and electric (cooling) consumption both rise across a shoulder-season period when only one should be active.
- [MET-08 Anomalous daily load shape](https://learn.pelorusengineering.com/faults/meter/met-08-anomalous-daily-load-shape/): One or more days have a load shape that doesn't fit any of the building's normal day-type clusters.
- [MET-09 Sudden step change in baseline](https://learn.pelorusengineering.com/faults/meter/met-09-sudden-step-change-in-baseline/): Baseload demand jumped discontinuously up or down on a specific date and didn't return.
- [MET-10 Meter data integrity issue](https://learn.pelorusengineering.com/faults/meter/met-10-meter-data-integrity-issue/): The interval data has gaps, frozen values, or implausible jumps that suggest a meter or telemetry problem rather than building behavior.
- [MET-11 Lighting on after hours](https://learn.pelorusengineering.com/faults/meter/met-11-lighting-on-after-hours/): The lighting submeter runs well above its normal unoccupied level outside the occupancy schedule.

## Air-side AHU (32 rules)

- [AHU-FC01 Duct static pressure cannot be met](https://learn.pelorusengineering.com/faults/ahu/ahu-fc01-duct-static-pressure-cannot-be-met/): The supply fan is at full speed but duct static pressure still isn't reaching its setpoint.
- [AHU-FC02 Mixed-air temperature below both OAT and RAT](https://learn.pelorusengineering.com/faults/ahu/ahu-fc02-mixed-air-temperature-below-both-oat-and-rat/): MAT is colder than both the outdoor air and the return air — physically impossible without a sensor or damper fault.
- [AHU-FC02/03/06 Mixed-air temperature doesn't match OA/RA mix](https://learn.pelorusengineering.com/faults/ahu/ahu-fc02-03-06-mixed-air-temperature-doesnt-match-oa-ra-mix/): The measured mixed-air temperature is inconsistent with what the OA damper position and the OAT/RAT temperatures predict it should be.
- [AHU-FC03 Mixed-air temperature above both OAT and RAT](https://learn.pelorusengineering.com/faults/ahu/ahu-fc03-mixed-air-temperature-above-both-oat-and-rat/): MAT is hotter than both the outdoor air and the return air — physically impossible without a fault.
- [AHU-FC04 Operating state hunting](https://learn.pelorusengineering.com/faults/ahu/ahu-fc04-operating-state-hunting/): The AHU is flipping between heating, free cooling, and mechanical cooling many times an hour.
- [AHU-FC05 Supply air not warming across active heating](https://learn.pelorusengineering.com/faults/ahu/ahu-fc05-supply-air-not-warming-across-active-heating/): Heating valve is open but SAT isn't rising above MAT by more than the fan-heat tolerance — the heating coil isn't delivering heat.
- [AHU-FC06 OA fraction wrong for current operating state](https://learn.pelorusengineering.com/faults/ahu/ahu-fc06-oa-fraction-wrong-for-current-operating-state/): The fraction of outside air being introduced doesn't match what the operating state calls for.
- [AHU-FC07 SAT low while heating valve is full open](https://learn.pelorusengineering.com/faults/ahu/ahu-fc07-sat-low-while-heating-valve-is-full-open/): Heating valve is saturated open but SAT still hasn't reached setpoint.
- [AHU-FC08 SAT and MAT not tracking in economizer](https://learn.pelorusengineering.com/faults/ahu/ahu-fc08-sat-and-mat-not-tracking-in-economizer/): In pure economizer mode (no mechanical heating or cooling), SAT should equal MAT plus the fan-heat rise — but it doesn't.
- [AHU-FC09 OAT too high for SAT setpoint with free cooling alone](https://learn.pelorusengineering.com/faults/ahu/ahu-fc09-oat-too-high-for-sat-setpoint-with-free-cooling-alone/): It's too hot outside to hit SAT setpoint without mechanical cooling, but the AHU is still in economizer mode.
- [AHU-FC10 Mixed air not tracking outdoor air at 100% OA](https://learn.pelorusengineering.com/faults/ahu/ahu-fc10-mixed-air-not-tracking-outdoor-air-at-100-oa/): With the outdoor-air damper fully open, the mixed-air temperature should equal the outdoor-air temperature — it doesn't.
- [AHU-FC11 Mechanical cooling with outdoor air cold enough to do the job](https://learn.pelorusengineering.com/faults/ahu/ahu-fc11-mechanical-cooling-with-outdoor-air-cold-enough-to-do-the-job/): The unit is at 100% outdoor air and still running the cooling coil, although the outdoor air alone is colder than the supply setpoint.
- [AHU-FC12 SAT too high relative to MAT in cooling mode](https://learn.pelorusengineering.com/faults/ahu/ahu-fc12-sat-too-high-relative-to-mat-in-cooling-mode/): When cooling is active, SAT should drop below MAT. If SAT is higher than MAT, cooling isn't working.
- [AHU-FC13 Supply air too warm with the cooling valve full open](https://learn.pelorusengineering.com/faults/ahu/ahu-fc13-supply-air-too-warm-with-the-cooling-valve-full-open/): The cooling coil is doing everything it can and the supply air is still above setpoint.
- [AHU-FC14 Temperature drop across inactive cooling coil](https://learn.pelorusengineering.com/faults/ahu/ahu-fc14-temperature-drop-across-inactive-cooling-coil/): Cooling valve is commanded closed but air is still being cooled as it crosses the coil.
- [AHU-FC15 Temperature rise across inactive heating coil](https://learn.pelorusengineering.com/faults/ahu/ahu-fc15-temperature-rise-across-inactive-heating-coil/): Heating valve is commanded closed but air is still being warmed as it crosses the coil.
- [AHU-X01 Fighting coils — heating and cooling on at the same time](https://learn.pelorusengineering.com/faults/ahu/ahu-x01-fighting-coils-heating-and-cooling-on-at-the-same-time/): The heating valve and the cooling valve are both driving open simultaneously on the same AHU.
- [AHU-X02 Reheat clawing back overcooled air](https://learn.pelorusengineering.com/faults/ahu/ahu-x02-reheat-clawing-back-overcooled-air/): Zone temperature dropped below setpoint and reheat then activated to recover — the AHU overcooled and is paying to heat back up.
- [AHU-X03 Fan power deviates from fan-curve expectation](https://learn.pelorusengineering.com/faults/ahu/ahu-x03-fan-power-deviates-from-fan-curve-expectation/): The fan is drawing more (or less) power than the affinity laws predict for its current speed.
- [AHU-X04 SAT setpoint is constant — no reset strategy](https://learn.pelorusengineering.com/faults/ahu/ahu-x04-sat-setpoint-is-constant-no-reset-strategy/): The supply-air-temp setpoint never moves across the analysis window, indicating no trim-and-reset or load-based reset is happening.
- [AHU-X05 Equipment running outside its occupancy schedule](https://learn.pelorusengineering.com/faults/ahu/ahu-x05-equipment-running-outside-its-occupancy-schedule/): A channel is showing active output during hours the building schedule says it should be off.
- [AHU-X06 Control loop oscillating](https://learn.pelorusengineering.com/faults/ahu/ahu-x06-control-loop-oscillating/): A control output is oscillating quickly enough that the loop is unstable.
- [AHU-X07 Sensor value frozen](https://learn.pelorusengineering.com/faults/ahu/ahu-x07-sensor-value-frozen/): A sensor's value hasn't changed beyond its noise floor for a long period when it should have.
- [AHU-X08 Valve pegged open or closed](https://learn.pelorusengineering.com/faults/ahu/ahu-x08-valve-pegged-open-or-closed/): A valve has been at 100% (or 0%) for sustained periods, suggesting it can't meet load.
- [AHU-X09 Supply fan riding high with no cooling demand](https://learn.pelorusengineering.com/faults/ahu/ahu-x09-supply-fan-riding-high-with-no-cooling-demand/): The supply fan is running above its minimum speed but the cooling load is near zero.
- [AHU-X10 Hot-water supply not following OAT reset](https://learn.pelorusengineering.com/faults/ahu/ahu-x10-hot-water-supply-not-following-oat-reset/): The hot-water supply temperature is too high for the current outdoor temperature — the reset schedule isn't being followed.
- [AHU-X11 Supply air temperature missing setpoint](https://learn.pelorusengineering.com/faults/ahu/ahu-x11-supply-air-temperature-missing-setpoint/): Supply air temperature is drifting above or below its setpoint by more than the tolerance.
- [AHU-X12 Reheat active during unoccupied hours](https://learn.pelorusengineering.com/faults/ahu/ahu-x12-reheat-active-during-unoccupied-hours/): Hot-water reheat is running at night or on weekends when the building should be unoccupied and unconditioned.
- [AHU-X13 Outside-air damper open past minimum without economizer reason](https://learn.pelorusengineering.com/faults/ahu/ahu-x13-outside-air-damper-open-past-minimum-without-economizer-reason/): The OA damper is open well past its minimum position even though OAT is too hot or too cold for free cooling to be useful.
- [AHU-X14 Mechanical cooling while free cooling was available](https://learn.pelorusengineering.com/faults/ahu/ahu-x14-mechanical-cooling-while-free-cooling-was-available/): Outdoor air is cool enough to provide free cooling, but the AHU is at minimum OA and running mechanical cooling instead.
- [AHU-X15 Static-pressure setpoint never resets](https://learn.pelorusengineering.com/faults/ahu/ahu-x15-static-pressure-setpoint-never-resets/): The supply-duct static-pressure setpoint sits at one value whenever the unit runs — there is no trim-and-respond reset from the VAV box dampers.
- [ERV-FC16 Energy recovery not recovering](https://learn.pelorusengineering.com/faults/ahu/erv-fc16-energy-recovery-not-recovering/): The recovery wheel or core is commanded on but the supply air isn't being pre-conditioned much by the exhaust stream.

## VAV / zone (7 rules)

- [VAV-01 VAV airflow sensor miscalibrated](https://learn.pelorusengineering.com/faults/vav/vav-01-vav-airflow-sensor-miscalibrated/): The VAV's airflow reading doesn't match what's expected from its damper position and the serving AHU's supply pressure.
- [VAV-02 VAV damper leaking when commanded closed](https://learn.pelorusengineering.com/faults/vav/vav-02-vav-damper-leaking-when-commanded-closed/): Damper command is at minimum but measured airflow is well above minimum and the serving fan is running.
- [VAV-03 VAV reheat valve leaking](https://learn.pelorusengineering.com/faults/vav/vav-03-vav-reheat-valve-leaking/): Reheat valve is commanded closed but discharge-air temperature is rising above supply-air temperature.
- [VAV-04 Zone outside its setpoint band](https://learn.pelorusengineering.com/faults/vav/vav-04-zone-outside-its-setpoint-band/): Zone temperature is sustained above the cooling setpoint or below the heating setpoint by more than the tolerance.
- [VAV-05 VAV reheat valve pegged but zone still cold](https://learn.pelorusengineering.com/faults/vav/vav-05-vav-reheat-valve-pegged-but-zone-still-cold/): Reheat valve has been at 100% but the zone temp is still below the heating setpoint.
- [VAV-06 VAV box stuck at min or max airflow](https://learn.pelorusengineering.com/faults/vav/vav-06-vav-box-stuck-at-min-or-max-airflow/): VAV airflow has been pinned at the minimum or maximum setpoint regardless of zone demand.
- [VAV-07 Single zone driving AHU reset](https://learn.pelorusengineering.com/faults/vav/vav-07-single-zone-driving-ahu-reset/): One VAV is consistently the most-open box and is driving the AHU's SAT reset target colder or hotter than the rest of the building needs.

## Zones & IAQ (10 rules)

- [FCU-01 Fan-coil valve leaking by](https://learn.pelorusengineering.com/faults/zone/fcu-01-fan-coil-valve-leaking-by/): The coil valve is closed but the discharge air is still well away from the zone temperature.
- [FCU-02 Fan-coil fan out of step with its call](https://learn.pelorusengineering.com/faults/zone/fcu-02-fan-coil-fan-out-of-step-with-its-call/): The fan runs unoccupied with the valve closed, or the valve opens while the fan is off.
- [FCU-03 Four-pipe fan-coil heating and cooling together](https://learn.pelorusengineering.com/faults/zone/fcu-03-four-pipe-fan-coil-heating-and-cooling-together/): Both the heating and cooling valves of a fan-coil are open at once.
- [ZONE-01 Over-ventilating a lightly occupied zone](https://learn.pelorusengineering.com/faults/zone/zone-01-over-ventilating-a-lightly-occupied-zone/): CO₂ is far below the demand-control setpoint while the outdoor-air damper is wide open.
- [ZONE-02 Under-ventilated zone (CO₂ high)](https://learn.pelorusengineering.com/faults/zone/zone-02-under-ventilated-zone-co2-high/): CO₂ stays above the comfort / code limit while the space is occupied.
- [ZONE-03 Zone humidity out of band](https://learn.pelorusengineering.com/faults/zone/zone-03-zone-humidity-out-of-band/): Occupied relative humidity sits outside the comfort band for a sustained period.
- [ZONE-04 Condensation risk on a chilled surface](https://learn.pelorusengineering.com/faults/zone/zone-04-condensation-risk-on-a-chilled-surface/): A chilled beam / radiant / supply surface is colder than the zone dewpoint.
- [ZONE-05 Zone temperature sensor biased vs neighbours](https://learn.pelorusengineering.com/faults/zone/zone-05-zone-temperature-sensor-biased-vs-neighbours/): One zone sensor reads persistently offset from the median of its neighbours.
- [ZONE-06 Occupied setpoints outside policy](https://learn.pelorusengineering.com/faults/zone/zone-06-occupied-setpoints-outside-policy/): During occupied hours the zone is asked for cooling colder, heating warmer, or a deadband narrower than the building's setpoint policy.
- [ZONE-07 Night setback too shallow](https://learn.pelorusengineering.com/faults/zone/zone-07-night-setback-too-shallow/): The unoccupied cooling and heating setpoints are within a few degrees of the occupied ones — the zone is kept at comfort conditions overnight and at weekends.

## Central plant (18 rules)

- [PLANT-01 Chiller can't make chilled-water supply setpoint](https://learn.pelorusengineering.com/faults/plant/plant-01-chiller-cant-make-chilled-water-supply-setpoint/): The chiller is on but CHW supply temperature is above its setpoint by more than the tolerance.
- [PLANT-02 Low chilled-water ΔT syndrome](https://learn.pelorusengineering.com/faults/plant/plant-02-low-chilled-water-delta-t-syndrome/): The chilled-water loop's supply-to-return delta is below design when the chiller is loaded.
- [PLANT-03 Condenser approach drifting up — likely tube fouling](https://learn.pelorusengineering.com/faults/plant/plant-03-condenser-approach-drifting-up-likely-tube-fouling/): The gap between condenser leaving water temp and refrigerant condensing temp has grown over time when normalized by load.
- [PLANT-04 Boiler and chiller running at the same time](https://learn.pelorusengineering.com/faults/plant/plant-04-boiler-and-chiller-running-at-the-same-time/): The building is calling for both heating and cooling at the central plant simultaneously.
- [PLANT-05 Pump running with no flow](https://learn.pelorusengineering.com/faults/plant/plant-05-pump-running-with-no-flow/): Pump status reads on but flow is at or near zero — the pump is deadheading against closed valves.
- [PLANT-06 Cooling-tower fan short-cycling](https://learn.pelorusengineering.com/faults/plant/plant-06-cooling-tower-fan-short-cycling/): The cooling tower's fan is starting and stopping more frequently than its minimum-runtime allows.
- [PLANT-07 Chiller short-cycling](https://learn.pelorusengineering.com/faults/plant/plant-07-chiller-short-cycling/): The chiller is starting and stopping more frequently than its minimum-runtime safety limit allows.
- [PLANT-07B Boiler short-cycling](https://learn.pelorusengineering.com/faults/plant/plant-07b-boiler-short-cycling/): The boiler is starting and stopping more frequently than its minimum-runtime safety limit allows.
- [PLANT-07D Chiller efficiency drifting](https://learn.pelorusengineering.com/faults/plant/plant-07d-chiller-efficiency-drifting/): The chiller uses more kW for the same cooling than it did at the start of the data.
- [PLANT-08 Chiller running at very low load](https://learn.pelorusengineering.com/faults/plant/plant-08-chiller-running-at-very-low-load/): The chiller idles below a quarter of its rated draw for hours.
- [PLANT-09 Chilled-water supply reset absent](https://learn.pelorusengineering.com/faults/plant/plant-09-chilled-water-supply-reset-absent/): The chilled-water supply setpoint stays flat for weeks while the weather swings.
- [PLANT-10 Condenser-water reset absent](https://learn.pelorusengineering.com/faults/plant/plant-10-condenser-water-reset-absent/): The condenser-water setpoint never follows the wet-bulb.
- [PLANT-11 Cooling-tower approach high](https://learn.pelorusengineering.com/faults/plant/plant-11-cooling-tower-approach-high/): Tower leaving water is far above the outdoor wet-bulb with the fans working.
- [PLANT-12 Tower fans overshooting setpoint](https://learn.pelorusengineering.com/faults/plant/plant-12-tower-fans-overshooting-setpoint/): Tower fans at full speed while the leaving water is already colder than setpoint.
- [PLANT-13 Decoupler reverse flow](https://learn.pelorusengineering.com/faults/plant/plant-13-decoupler-reverse-flow/): The secondary loop pulls more water than the primary supplies.
- [PLANT-14 Condensing boiler not condensing](https://learn.pelorusengineering.com/faults/plant/plant-14-condensing-boiler-not-condensing/): Hot-water return to a condensing boiler is warm enough that the flue gas cannot condense, so the boiler runs as a conventional one.
- [PLANT-15 Hot-water loop low ΔT](https://learn.pelorusengineering.com/faults/plant/plant-15-hot-water-loop-low-delta-t/): The hot-water loop ΔT collapses while the boiler runs.
- [PLANT-16 Pump ΔP reset absent](https://learn.pelorusengineering.com/faults/plant/plant-16-pump-delta-p-reset-absent/): The secondary pump differential-pressure setpoint is flat for weeks.

## Packaged RTU / DX (7 rules)

- [RTU-01 Compressor short-cycling](https://learn.pelorusengineering.com/faults/rtu/rtu-01-compressor-short-cycling/): The compressor is starting far more often than a healthy unit should.
- [RTU-02 Cooling / heating stage hunting](https://learn.pelorusengineering.com/faults/rtu/rtu-02-cooling-heating-stage-hunting/): A stage is flipping on and off many times an hour.
- [RTU-03 DX cooling capacity degraded](https://learn.pelorusengineering.com/faults/rtu/rtu-03-dx-cooling-capacity-degraded/): On hot days with the compressor running the supply air is not getting as cold as the coil should make it.
- [RTU-04 Integrated economizer not used](https://learn.pelorusengineering.com/faults/rtu/rtu-04-integrated-economizer-not-used/): The compressor runs while outdoor air is cool enough for free cooling and the damper is parked at minimum.
- [RTU-05 Heat and cool stages on together](https://learn.pelorusengineering.com/faults/rtu/rtu-05-heat-and-cool-stages-on-together/): A heating stage and a compressor stage are energized at the same time.
- [RTU-06 Supply fan running after hours with no call](https://learn.pelorusengineering.com/faults/rtu/rtu-06-supply-fan-running-after-hours-with-no-call/): The fan runs outside the schedule with neither heating nor cooling active.
- [RTU-07 High compressor runtime on cool days](https://learn.pelorusengineering.com/faults/rtu/rtu-07-high-compressor-runtime-on-cool-days/): On days cool enough that mechanical cooling should barely run, the compressor runs most of the time.

## Heat pumps / VRF (6 rules)

- [HP-01 Auxiliary heat without lockout](https://learn.pelorusengineering.com/faults/hp/hp-01-auxiliary-heat-without-lockout/): Electric resistance / auxiliary heat runs while it is warm enough for the compressor to carry the load.
- [HP-02 Excessive defrost](https://learn.pelorusengineering.com/faults/hp/hp-02-excessive-defrost/): The outdoor coil is defrosting far more than it should.
- [HP-03 Heat-pump compressor short-cycling](https://learn.pelorusengineering.com/faults/hp/hp-03-heat-pump-compressor-short-cycling/): The heat-pump compressor is starting far more often than a healthy unit should.
- [HP-04 Reversing valve / mode mismatch](https://learn.pelorusengineering.com/faults/hp/hp-04-reversing-valve-mode-mismatch/): The unit says heating but the supply air is colder than return (or the opposite in cooling).
- [VRF-01 VRF indoor units in conflicting modes](https://learn.pelorusengineering.com/faults/hp/vrf-01-vrf-indoor-units-in-conflicting-modes/): On a heat-pump (non-heat-recovery) VRF system, some indoor units call for heating while others call for cooling.
- [VRF-02 VRF indoor unit runtime imbalance](https://learn.pelorusengineering.com/faults/hp/vrf-02-vrf-indoor-unit-runtime-imbalance/): One indoor unit runs several times longer than its siblings.

## DOAS / ERV / exhaust (5 rules)

- [BP-01 Building pressure out of band](https://learn.pelorusengineering.com/faults/doas/bp-01-building-pressure-out-of-band/): Building static pressure is negative or excessive during occupancy.
- [DOAS-01 DOAS supply setpoint not met](https://learn.pelorusengineering.com/faults/doas/doas-01-doas-supply-setpoint-not-met/): The dedicated outdoor-air unit's supply temperature misses its setpoint for an hour or more while running.
- [EF-01 Exhaust running without supply](https://learn.pelorusengineering.com/faults/doas/ef-01-exhaust-running-without-supply/): Exhaust fans run while the supply fan is off.
- [EF-02 Exhaust running outside the schedule](https://learn.pelorusengineering.com/faults/doas/ef-02-exhaust-running-outside-the-schedule/): General exhaust runs during unoccupied hours.
- [ERV-02 Energy-recovery bypass open when recovery pays](https://learn.pelorusengineering.com/faults/doas/erv-02-energy-recovery-bypass-open-when-recovery-pays/): The recovery bypass is open while indoor and outdoor temperatures differ a lot.