ASHRAE Guideline 13 — Data Management
What it means on the job
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.
Tested in 1 CraftIQ puzzle
- whats-wrongTrending and Data Logging Setup
Related ASHRAE sections
ASHRAE Fundamentals Handbook — Hydronic System Design
The decoupler pipe should not have isolation valves — this is correct as installed. However, the decoupler pipe connections are spaced only 2 pipe diameters apart. Connections must be spaced at least 6-10 pipe diameters apart to prevent flow turbulence and ensure proper hydraulic separation.
ASHRAE Guideline 12 — Minimizing the Risk of Legionellosis
Without automatic blowdown control, condenser water cycles of concentration are unmanaged. Manual blowdown is unreliable and either wastes water (over-blowing) or allows mineral concentration to build (under-blowing). An automatic conductivity controller with a motorized blowdown valve is required to maintain proper cycles of concentration (typically 3-6 cycles).
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 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.
CraftIQ explanations are original educational commentary written in trade language and verified against the cited standards. Always confirm requirements against the code edition adopted by your jurisdiction — this is training material, not a substitute for the code book or your AHJ.