Applicable Systems
- Secondary: VAV, HP, FCU, UV, UH, RAD, RHT
Description / Method
Determine if the zone temperature control is taking too long to reach its desired setpoint, on system startup. Check the amount of time the RT takes to reach within 1 degree of its set point. This check only occurs after the system is enabled and before the temperature setpoint is reached.
Logic
Inputs
- RT {sensor, zone, air, temp} (Real Trend Log)
- RT SP {sp, zone, air, temp} (Real Trend Log)
- Occ {occupied} (Binary Trend Log)
Rule Template Type
- Insight Type: Fault Detection
- Trigger Type: Active High
Diagnosis / Recommended Action
- Input sensor(s) faulty or miscalibration. Verify input sensor(s) operation.
- Chilled water not available. Verify chiller plant operation.
- Heating water not available. Verify boiler plant operation.
- Automatic control has been overridden. Revert equipment back to automatic control.
- Issue with control loop. Review and modify controller tuning parameters.
- Primary air not available. Verify Air Handling Unit operation.
Message
The total time the RT takes be within 1 degree of set point on system startup is longer than 2 hours per week.
Notes
This logic flow only activates the initialization of the unit. If the temperature falls below the set point a second time, this will purposefully not trigger. However, this rule will activate every time a unit engages. If the unit changes status multiple times per day, a building occupancy trend log may be more suitable to define unit status.
Parameters
| Parameter | Expression Block Series Number | Description | *Default Value (Units) |
|---|---|---|---|
| Temperature Threshold | 7 | The acceptable temperature range the RT has to enter to be considered normal. | 1 (C) |
| Acceptable hours per day to reach Set Point | 26 | The amount of time that this error is allowable for the unit per day. Anything more than that time is considered a fault. | 1.75 (h) |
Calculated Trend Logs
| Name | Expression Block Series Number | Description |
|---|---|---|
| CalculatedTrendLog24 | 24 | The amount of time (hours) the HWST temp to reach set point. |
