Applicable Systems
- Primary: AHU, RTU, MUA, ERV
Objective/Method/Outcome
- Objective: Determine if an air heating system is at full capacity but unable to meet set point.
- Method: Check if the SAT is more than 2 degrees below its set point when the HCV is at its maximum value when equipment is on.
- Outcome: An insight is generated if the weekly errors exceed the acceptable hours per week of irregularity.
Logic
- Input normalized heat coil valve, supply air temperature, and supply air temperature setpoint, with their desired threshold constants.
- If both heating coil valve and supply air temperatures exceed their thresholds, and the building is active, calculate the weekly hours of error.
- If the weekly hours of errors exceed the acceptable hours per week, an insight is generated.
while( HCV > Error Threshold AND SAT > Temperature Threshold AND Building Active ){
Aggregate Weekly Hour Errors
if( Weekly Errors > Acceptable Weekly Hours ){
Insight- HCV fully open and SAT Error exists
}
}
Description / Method
Determine if an air heating system is at full capacity but unable to meet set point. {AHU|RTU|MUA|ERV} Check if the SAT is more than 2 degrees below its set point when the HCV is at its maximum value during occupied hours.
Diagnosis / Recommended Action
- Input sensor(s) faulty or miscalibration. Verify input sensor(s) operation.
- Cooling coil valve stuck and/or leaking. Verify valve/actuator operation.
- Heating coil valve stuck, seized, and/or undersized. Verify valve/actuator operation.
- Heating water not available. Verify boiler plant operation.
Message
The SAT is more than 2 degrees below set point for over 8 occupied hours per week while the HCV is open. Please verify HCV/actuator operation.
Notes
This rule is not applicable if dehumidification is used.This rule is designed for °C inputs by default.Default Constants:
- Const. – Acceptable Weekly Score [%]: 60
- Const. – Heating Water Supply Deadband [°C]: 1.5
(Recommended default Deadband for Fahrenheit is 3 °F)
Rule Template Type
- Insight Type: Fault Detection
- Trigger Type: Active High
Default Priority
Medium
Default Priority
Low
Inputs
| Inputs | Units | Default Value | Tags | Description |
|---|---|---|---|---|
| Supply Fan Status | status|cmd|feedback|occupied | Equipment status indicator | ||
| Heating Coil Valve | % | Heating coil valve position | ||
| Supply Air Temperature | °C/°F | sensor, discharge, air, temp | Temperature of incoming supply air | |
| Const. – Supply Air Temperature Deadband | °C/°F | 2 | Deadband that dictates how “close” the supply air temperature needs to be to the setpoint | |
| Const. – Acceptable Hours per Week | 8 | Number of hours of fault occurrences that can happen without triggering an insight | ||
| Supply Air Temperature Set Point | °C/°F | sp, discharge, air, temp | Setpoint of the incoming supply air temperature |
Output Calculated Trend Logs
| Output CTL | Units | Description |
|---|---|---|
| Weekly Hours SAT Lower Than SP HCV Open | Number of weekly hours the SAT is lower than the SP while HCV Open |
