NIST APAR7 – Supply and mixed air temp should be nearly the same (Mode 2 – Cooling w/OA)

Applicable Systems

  • NISTAPAR: APAR7
  • Primary: AHU, RTU, MUA, ERV

Objective/Method

  • Objective: Indicates an inconsistency between supply and mixed air temperatures while the unit is in Mode 2 (Cooling w/OA)
  • Method: Check if the SAT is more than +/-2 degrees from the MAT for over 8 occupied hours per week while the unit is in Mode 2

Logic

If (absolute(SAT - Temperature Rise Over Fan - MAT) > Temperature Threshold){ return true; }
NIST APAR7 – Supply and mixed air temp should be nearly the same (Mode 2 – Cooling w/OA)

Inputs

  • SAT {sensor, discharge, air, temp} (Real Trend Log)
  • AHU_MODE_CTL {ahu, mode} (Real Trend Log)
  • MAT {sensor, mixed, air, temp} (Real Trend Log)

Parameters

ParameterExpression Block Series NumberDescriptionDefault Value (Units)
Temperature Threshold30This is the minimum temperature difference between SAT and MAT needed to enable the rule.2 (C)
Const – Temperature Rise Over Fan31The estimated air temperature rise over the fan1.1 (C)
Acceptable Hours per Week33The amount of time that this error is allowable for the unit per week. Anything more than that time is considered a fault.8 (h)
image_printPrint