NIST APAR10 – Outdoor and mixed air temp should be nearly the same (Mode 3 – Mech. Cooling w/100% OA)
Applicable Systems
NISTAPAR: APAR10
Primary: AHU, RTU, MUA, ERV
Objective/Method/Outcome
Objective: Indicates an inconsistency between outdoor and mixed air temperatures while the unit is in Mode 3 (Mech. Cooling w/100% OA)
Method: Check if the MAT is more than +/-2 degrees from the OAT for over 8 occupied hours per week while the unit is in Mode 3 (Mech. Cooling w/100% OA).
Outcome: An insight is generated when the MAT is more than +/-2 degrees from the OAT for over 8 occupied hours per week while the unit is in Mode 3.
Logic
If (absolute(MAT-OAT) > Temperature Threshold) { return true; }
NIST APAR10 – Outdoor and mixed air temp should be nearly the same (Mode 3 – Mech. Cooling w/100% OA)
Inputs
OAT {sensor, outdoor, air, temp} (Real Trend Log)
AHU_MODE_CTL {ahu, mode} (Real Trend Log)
MAT {sensor, mixed, air, temp} (Real Trend Log)
Parameters
Parameter
Expression Block Series Number
Description
Default Value (Units)
Temperature Threshold
30
This is the minimum temperature difference between OAT and MAT needed to enable the rule
2 (C)
Acceptable Hours per Week
33
The amount of time that this error is allowable for the unit per week. Anything more than that time is considered a fault.
