ASHRAE Guideline 13, Specifying Building Automation Systems (advisory) — applied through the project BAS specification, Division 25

ASHRAE Fundamentals Handbook — Hydronic System Design

The decoupler (common) pipe connections must be spaced at least 4 to 6 pipe diameters apart so primary and secondary loops are genuinely hydraulically decoupled; at 2 diameters the two loops interact and flow in the common pipe no longer reflects the true surplus or deficit. Note what is NOT the defect here: the absence of isolation valves on the decoupler is CORRECT as installed — valving the common pipe would defeat decoupling entirely.

ASHRAE Guideline 13 — Alarm Management

Alarms must be prioritized based on severity. A freeze stat alarm (life-safety) should be higher priority than a dirty filter alarm (maintenance). Without prioritization, critical alarms get lost in nuisance alarms, a condition called 'alarm flooding'.

ASHRAE Guideline 13 — Data Management

Storing trend data only in field controllers risks data loss when controllers are reset or lose power. Trend data should be archived to the BAS server or a dedicated historian. Controller memory is limited and will overwrite oldest data.

ASHRAE Guideline 36 — Chiller Staging

Staging a lag chiller immediately at 100% lead capacity causes hunting and instability. A time delay (typically 10-15 minutes) and sustained load confirmation are required to prevent short-cycling. ASHRAE Guideline 36 specifies staging criteria with time delays and load verification.

ASHRAE Guideline 36 — Cooling Coil Control

Cooling coil control valves should fail closed (spring return to closed) on loss of signal or power. Failing open causes uncontrolled cooling and potential freezing of downstream coils or spaces.

ASHRAE Guideline 36 — Damper/Fan Interlocks

An end switch or position feedback must confirm the motorized outside air damper is fully open before the evaporator fan is allowed to start. Starting the fan with the damper closed creates high negative pressure in the ductwork and starves the unit of ventilation air, potentially damaging ductwork and causing inadequate outdoor air delivery.