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TOWER Fault Rules

Cooling tower rules (TOWER-*) are fully library-authored: no HVAC FDD Reference chapter covers towers. BEE, DOE/PNNL, NREL, ASHRAE, SPX, and EVAPCO sources corroborate the mechanisms and safety constraints, but they do not publish portable executable limits for approach/range degradation, loaded-fan overcooling, proof timing, or basin thermal response. Each card therefore labels adopted values and site/OEM adoption blockers explicitly.

The first batch’s quantitative grounding remains the committed 4-climate simulation study (tools/simharness README, “Tower groundwork”): healthy approach spans 1.6–13.3 °C un-gated purely on VFD fan modulation, which is why TOWER-0001 is fan-at-capacity gated, while range holds a stable healthy band. TOWER-0003’s 4–5 starts/hour mechanism is literature-backed. TOWER-0004..0006 add per-fan proof, loaded-fan overcooling, and an explicitly site/OEM-governed wet-basin freeze watchdog.

Point dictionary: points/tower.points.json — note the loop-side semantics (tower-leaving = cold = entering condenser water), the oa_wetbulb host psychrometric obligation, and provisional 223 topology for basin points.

Index

IDNameSevMethodStatus
TOWER-0001Tower approach high at fan capacity3ruleverified
TOWER-0002Tower range collapse3ruleverified
TOWER-0003Tower fan short-cycling3ruleverified
TOWER-0004Tower fan proof-of-operation failure2ruleverified
TOWER-0005Condenser water overcooling with fan energy3ruleverified
TOWER-0006Cooling-tower basin freeze-protection failure2ruleverified

Relationships

  • CLU-10 (Condenser-Side Degradation): TOWER-0001 is the trigger, TOWER-0002 and CHW-0005 (chiller condenser approach) the members; playbooks/cooling-tower-performance.md is the family playbook. CHW-0005 is the tube-side vs fill-side discriminator: tower approach normal + condenser approach high → clean the tubes, not the fill.
  • TOWER-0003 stays outside CLU-10 — a drive/control fault, not the degradation syndrome; it shares the playbook’s control-side steps.
  • TOWER-0004 and TOWER-0005 stay outside CLU-10. Proof disagreement and overcooling control waste do not share the cluster’s degradation repair contract. TOWER-0004 is direction-sensitive proof context for TOWER-0005; no static whole-rule suppression is safe.
  • TOWER-0006 stays independent and synthetic-only. It applies only to a wet, filled basin with monitored heater/equivalent protection and configured site/OEM limits. A basin heater is not protection for external piping.
  • The pending primary sources when they are acquired: a CTI/ASHRAE tower chapter for approach/range fault bands, ASHRAE RP-1043 for the chiller condenser-approach threshold.