NIST APAR22 – Heating/cooling control is overlapping (Mode 5 – Unknown Occupied Mode)
Applicable Systems
NISTAPAR: APAR22
Primary: AHU, RTU, MUA, ERV
Objective/Method/Outcome
Objective: Indicates that the HCV and the CCV are both open at the same time during occupied hours.
Method: Check if the HCV and CCV are open at the same time for over 8 occupied hours per week while the unit is in Mode 5.
Outcome: An insight is generated when the HCV and CCV are open at the same time for over 8 occupied hours per week while the unit is in Mode 5.
Logic
If (CCV > 2% Open && HCV > 2% Open) { return true; }
NIST APAR22 – Heating/cooling control is overlapping (Mode 5 – Unknown Occupied Mode)
Inputs
CCV {cmd, cool, water, valve} (Real Trend Log)
HCV {cmd, heat, water, valve } (Real Trend Log)
AHU_MODE_CTL {ahu, mode} (Real Trend Log)
Parameters
Parameter
Expression Block Series Number
Description
Default Value (Units)
CCV and CCV Error Threshold
70
The movement tolerance of the CCV. This is used to define when the valve is open -everything above the formula (100 – CCV Error Threshold) is considered saturated.
0 (%)
Acceptable Hours per Week
73
The amount of time that this error is allowable for the unit per week. Anything more than that time is considered a fault.
