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ERV Fault Rules

Energy recovery ventilator fault detection rules (ERV-*). Source grounding: HVAC FDD Reference v1.0 ch.15 (Energy Recovery — adapted authority; see each card’s Deviations section) plus clearly labeled library-authored operating, proof, and airflow-balance extensions.

Point dictionary: points/erv.points.json.

Index

IDNameSevMethodStatus
ERV-0001Sensible effectiveness degradation3statisticalverified
ERV-0002Frost protection not engaging2ruleverified
ERV-0003Frost protection active above release conditions3ruleverified
ERV-0004Recovery device proof-of-operation failure2ruleverified
ERV-0005Supply/exhaust airflow imbalance3ruleverified

ERV-0001/0002 adapt the reference chapter. ERV-0003..0005 are library-authored: the cards classify every threshold and name their reusable graph precedents.

Applicability and point availability

  • Passive plate cores: ERV-0001, ERV-0002/0003 where a frost-state point exists, and ERV-0005 where both device-local flow measurements exist. ERV-0004 is not applicable because the core has no commanded active device.
  • Rotary wheels: all five rules may apply. ERV-0004 needs a final wheel-run command and independent rotation/speed proof; command echo is not proof.
  • Runaround loops: all five rules may apply where a frost sequence/state exists and temperatures/flows map to both air streams. ERV-0004 binds the loop pump’s final command and independent pump work/rotation proof.
  • Point scarcity: enabled/frost flags and three temperatures do not imply command/status proof or two comparable airflow measurements. Omit a rule rather than substitute a high-level enable or an unrelated AHU flow meter.

Relationships

  • All rules share the erv-effectiveness investigation order. ERV-0004 also uses proof-of-operation for command/status diagnosis.
  • ERV-0003 relates to both existing frost/effectiveness rules but suppresses neither: excessive frost protection can be the real cause of lost recovery.
  • ERV-0005’s direction flags identify the air path to inspect; yFlowOk=false means NO_EVAL, not balanced operation.