Applicable Systems
- Primary: AHU, RTU, MUA, ERV, UV
Objective/Method/Outcome
- Objective: Determine if a heating and cooling control sequence overlap exists.
- Method: Check if the HCV and the CCV are both open while the unit is on.
- Outcome: An insight is generated if the amount of time the HCV and CCV are open simultaneously in a week exceeds the allowable hours’ threshold.
Logic
- Input both (normalized to 5-minute inputs) cooling and heating coil valve readings against the valve open threshold allowed.
- The coil valve is ‘open’ if the open threshold is exceeded.
- If the unit is on and both coil valves are open for at least one hour, calculate the hours of irregularity.
- Aggregate hours on a weekly basis.
- If weekly hours exceed the allowable hours per week, generate an insight.
if( CCV > Open Threshold && HCV > Open Threshold && Unit is On ) { Count hours if (Hours > Weekly Acceptable hours) { Trigger insight - HCV and CCV are simultaneously open } }
Description / Method
Determine if a heating and cooling control sequence overlap exists by checking if the heating coil valve and the cooling coil valve are both open while the unit is on. {AHU|RTU|MUA|ERV|UV}
Diagnosis / Recommended Action
- Error in the control sequence. Review and modify the programmed sequence of operations.
- Automatic control has been overridden. Revert equipment back to automatic control.
Message
The heating coil valve and cooling coil valve are simultaneously open for over 4 hours in the week. Review and modify the programmed sequence of operations.
Notes
Not valid for systems using the cooling coil for de-humidification as well as cooling.Default logic flow is designed for % open, where the CCV/HCV is considered open beyond 2%Default Constants:
- Const. – Valve Open Threshold [%]: 2
- Const. – Acceptable Hours per Week [hrs]: 4
CTL Generated:
- Weekly Hours CCV/HCV Overlap
Rule Template Type
- Insight Type: Fault Detection
- Trigger Type: Active High
Default Priority
High
Inputs
Inputs | Units | Default Value | Tags | Description |
---|---|---|---|---|
Cooling Coil Valve | % | cmd, cool, water, valve | Cooling coil valve position (command or feedback) | |
Heating Coil Valve | % | cmd, heat, water, valve | Heating coil valve position (command or feedback) | |
Equipment Status | fan, status|cmd | Unit on status. Alternatively, building occupancy can be used | ||
Const. – Valve Open Threshold | % | 2 | Value above which the coil valve is considered open | |
Const. – Allowable Hours per Week | hrs | 4 | The acceptable hours of overlap per week |
Output Calculated Trend Logs
Output CTL | Units | Description |
---|---|---|
Weekly Hours CCV/HCV Overlap | hrs | Trended number of hours per week that CCV and HCV are open simultaneously |