ASHRAE Guideline 36 / Manufacturer Requirements
What it means on the job
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.
Tested in 1 CraftIQ puzzle
- whats-wrongChiller Plant Staging Sequence
Related ASHRAE sections
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 maintenance requirements
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.
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.
ASHRAE Handbook — HVAC Applications, Water Treatment
Visible scale on condenser tubes indicates water treatment failure. Scale acts as insulation on heat transfer surfaces — 1/16" of scale increases energy consumption by approximately 11%. The condenser must be chemically or mechanically cleaned, and the water treatment program must be corrected to prevent recurrence.
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.