ASHRAE Guideline 36 / Manufacturer maintenance requirements
What it means on the job
Dirty CRAH coils reduce heat transfer efficiency significantly, potentially losing 20-40% of cooling capacity. Regular coil cleaning is required per ASHRAE maintenance guidelines. Reduced capacity leads to higher server inlet temperatures and potential thermal shutdowns.
Tested in 1 CraftIQ puzzle
- whats-wrongCRAH Unit Issues
Related ASHRAE sections
ASHRAE Guideline 36 — Section 5.18
The installed sensors meet the specification. ASHRAE Guideline 36 recommends space temperature sensors with accuracy of +/- 0.5 degrees F or better for zone control. The 10K thermistor is a standard sensor type for DDC systems, providing adequate accuracy for HVAC zone control.
ASHRAE Guideline 36 — Sensor Placement
Temperature sensors must not be placed in direct airflow from supply diffusers. The supply air temperature causes false readings, making the controller unable to maintain proper space temperature setpoint.
ASHRAE Guideline 36 / Crestline Controls Specification
Duct temperature probes must be inserted 25-50% of the duct width to obtain a representative reading. Inserting only 10% places the sensor in the boundary layer near the duct wall where temperature is not representative of the airstream, causing inaccurate control.
ASHRAE Guideline 36 / Manufacturer Requirements
Chillers require a minimum runtime (typically 15-30 minutes) and minimum off-time (typically 15 minutes) to prevent compressor short-cycling. Frequent starts damage the compressor motor and reduce equipment life.
ASHRAE Handbook — Fundamentals, Chapter 7
A thermostat behind a door that is typically held open will be in stagnant air and will not sense the true space temperature. It must be in an area with representative airflow of the occupied zone.
ASHRAE Handbook — HVAC Applications
Rooftop units must have vibration isolation to prevent noise and vibration transmission to the building structure. Required by ASHRAE and most building codes.
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.