Heat Pump Water-Side Bypass System - Design Guide
IMPORTANT DISCLAIMER
This document provides conceptual design guidance and should NOT be used for construction without professional engineering review and approval. All specifications, calculations, and recommendations must be verified by a licensed mechanical and electrical engineer familiar with your specific installation.
Executive Summary
This document provides sample design specifications and programming details for implementing a water-side bypass system for condominium heat pump units connected to a central condenser water loop. The system enables automatic bypass of individual heat pump condensers based on apartment temperature requirements, potentially reducing energy consumption while maintaining proper water circulation throughout the building.
CRITICAL ENGINEERING REQUIREMENTS:
Licensed mechanical engineer must perform hydraulic analysis
Heat pump manufacturer approval required for condenser modifications
Local code compliance verification mandatory
Professional commissioning and balancing required
Table of Contents
System Overview
Current Configuration
Individual heat pump units in each apartment
Central condenser water loop serving all units
Association-provided condenser water circulation
Individual apartment temperature control
Proposed Bypass System Concept
The water-side bypass system would redirect condenser water around individual heat pump condensers when cooling is not required, while maintaining continuous circulation through the main building loop.
⚠️ ENGINEERING VERIFICATION REQUIRED:
Hydraulic compatibility with existing system
Impact on building-wide flow balance
Heat pump manufacturer warranty implications
Integration with existing controls
Engineering Considerations
1. Hydraulic Analysis Requirements
MUST BE PERFORMED BY LICENSED ENGINEER:
Flow Calculations:
Existing condenser water flow rates for each unit
Pressure drop analysis through heat pump condensers vs. bypass lines
Building loop pressure and flow balance verification
Pump capacity and head requirements with bypass operation
Potential for cavitation or flow reversal conditions
System Interactions:
Effect on other units when individual bypasses activate
Building loop pressure stability during transition periods
Minimum flow requirements for central circulation pumps
Thermal expansion and contraction effects
2. Heat Pump Compatibility
MANUFACTURER APPROVAL REQUIRED:
Condenser water flow modification acceptance
Warranty impact assessment
Minimum flow requirements for proper operation
Control interface compatibility
Service access implications
3. Building System Integration
PROFESSIONAL ASSESSMENT NEEDED:
Existing building automation system compatibility
Electrical system capacity for additional controls
Structural requirements for new piping and equipment
Fire safety system interactions
Accessibility code compliance
Technical Components
1. Three-Way Motorized Valves
⚠️ SIZING MUST BE VERIFIED BY ENGINEER
Primary Bypass Valves (Supply Side) - CONCEPTUAL SPECIFICATIONS:
Type: Motorized three-way mixing/diverting valves
Size: TO BE DETERMINED based on actual flow calculations
Actuation: 24VAC or 120VAC electric actuator with 90-second stroke time
Cv Rating: TO BE CALCULATED based on system requirements
Materials: Bronze or stainless steel body for condenser water service
End Connections: Match existing piping configuration
Pressure Rating: Match or exceed existing system pressure
Secondary Bypass Valves (Return Side) - CONCEPTUAL:
Type: Motorized three-way mixing valves
Purpose: Ensure proper flow balance and prevent deadheading
Specifications: TO BE MATCHED TO SUPPLY VALVE SIZING
Control: Synchronized operation with supply valve
CRITICAL ENGINEERING NOTES:
Valve sizing requires detailed Cv calculations
Pressure drop analysis essential for proper selection
Flow characteristics must match system requirements
Actuator torque requirements based on system pressures
2. Flow Control and Balancing
⚠️ REQUIRES PROFESSIONAL HYDRAULIC DESIGN
Bypass Line Components - CONCEPTUAL:
Pipe Size: TO BE DETERMINED by flow calculations
Flow Control Valve: Manual balancing valve in bypass line
Pressure Relief: Bypass line pressure relief valve SET BY ENGINEER
Insulation: Match existing condenser water piping specification
Expansion Joints: As required by thermal analysis
Flow Measurement - VERIFICATION REQUIRED:
Flow Meters: Ultrasonic or electromagnetic type
Accuracy: ±2% of reading minimum
Digital Output: 4-20mA signal for building automation integration
Installation: Per manufacturer requirements with proper straight runs
3. Control System Architecture
PROFESSIONAL PROGRAMMING REQUIRED
Individual Unit Controllers - CONCEPTUAL SPECIFICATIONS:
Type: Programmable logic controller (PLC) or smart relay
Processing Power: 32-bit processor with 1MB memory minimum
Operating Temperature: 32°F to 122°F
Humidity Rating: 5% to 95% non-condensing
Power Supply: 120VAC, 60Hz with backup capabilities
Input Requirements:
Room temperature sensor (4-20mA or RTD)
Existing thermostat interface signals
Flow measurement signals
Valve position feedback
Manual override switches
System status indicators
Output Requirements:
Valve actuator control (24VAC)
Status indication (LED/LCD display)
Alarm relay outputs
Communication interface to building system
Temperature Sensors - ACCURACY CRITICAL:
Type: RTD (PT100/PT1000) or precision thermistor
Accuracy: ±0.5°F over operating range
Response Time: 30 seconds maximum in still air
Signal Conditioning: 4-20mA transmitter output
Calibration: Annual calibration required
4. Electrical and Control Infrastructure
⚠️ ELECTRICAL ENGINEER REVIEW REQUIRED
Power Requirements - ESTIMATED:
Valve Actuators: 24VAC, 5VA typical per actuator
Controllers: 120VAC, 15W typical per unit
Sensors: 24VDC, 4-20mA loop powered
Total Load: TO BE CALCULATED for building electrical capacity
Control Wiring - CODE COMPLIANCE REQUIRED:
Low Voltage: 18 AWG, 2-conductor shielded cable
Control Power: 16 AWG, 2-conductor minimum
Communication: Cat5e/Cat6 for digital networks
Conduit: EMT or flexible conduit per local electrical code
Grounding: Proper grounding and bonding per NEC requirements
Installation Requirements
1. Piping Modifications
⚠️ LICENSED PLUMBER/PIPEFITTER REQUIRED
Bypass Piping Installation - GENERAL GUIDANCE:
Location: Install connections as close to heat pump as practical
Pipe Routing: Direct bypass avoiding heat pump condenser
Support: Pipe hangers per SMACNA or local code requirements
Isolation: Install isolation valves for maintenance access
Drainage: Low point drains for system maintenance
Pressure Testing: Test per local plumbing code requirements
Valve Installation - CRITICAL REQUIREMENTS:
Orientation: Follow manufacturer specifications exactly
Clearances: Maintain required clearances for actuator operation
Support: Independent support for valve weight
Accessibility: Provide access for maintenance and service
Insulation: Insulate valve bodies to prevent condensation
2. Control System Installation
⚠️ LICENSED ELECTRICIAN REQUIRED
Controller Mounting - CODE COMPLIANCE:
Enclosure: NEMA 1 minimum for indoor installation
Working Space: Maintain NEC required clearances
Ventilation: Adequate ventilation per manufacturer requirements
Grounding: Proper equipment grounding per NEC
Labeling: Clear identification of all circuits and equipment
Sensor Installation - ACCURACY CRITICAL:
Location: Representative temperature measurement point
Protection: Avoid direct sunlight, drafts, heat sources
Wiring: Separate conduit from power wiring
Shielding: Proper shield grounding for interference prevention
Calibration: Initial calibration and verification required
Complete Control Programming
1. Programming Architecture
⚠️ PROFESSIONAL PROGRAMMER REQUIRED - CONCEPTUAL LOGIC ONLY
System Variables and Data Types:
// System Status Variables - EXAMPLES ONLY
BOOL SystemFault = FALSE
BOOL ManualOverride = FALSE
BOOL SystemStartup = TRUE
BOOL BypassEnabled = FALSE
BOOL CoolingCall = FALSE
BOOL FanCall = FALSE
// Analog Variables - TYPICAL VALUES
REAL RoomTemp = 0.0 // °F
REAL FilteredTemp = 0.0 // °F, filtered
REAL CoolingSetpoint = 75.0 // °F - ADJUSTABLE
REAL ValvePosition = 0.0 // 0-100%
REAL FlowRate = 0.0 // GPM
REAL CoolingDeadband = 2.0 // °F - TO BE OPTIMIZED
// Timer Variables - TYPICAL VALUES
DINT SystemStartupTimer = 0 // seconds
DINT StateTimer = 0 // seconds
DINT TransitionTimer = 0 // seconds
DINT FlowAlarmTimer = 0 // seconds
DINT PositionFaultTimer = 0 // seconds
// System Constants - MUST BE FIELD DETERMINED
REAL NominalFlow = 10.0 // GPM - ACTUAL VALUE REQUIRED
REAL MinimumFlow = 5.0 // GPM - ENGINEER TO DETERMINE
REAL RampRate = 1.0 // %/second - OPTIMIZE DURING COMMISSIONING
DINT MinimumRuntime = 600 // seconds - ADJUSTABLE
State Machine Definitions - CONCEPTUAL:
// Primary Control States - EXAMPLE IMPLEMENTATION
ENUM SystemState:
STARTUP = 0
NORMAL_COOLING = 1
BYPASS_COOLING = 2
TRANSITION_TO_BYPASS = 3
TRANSITION_TO_NORMAL = 4
FAULT = 5
MANUAL_OVERRIDE = 6
// Current state tracking
SystemState CurrentState = STARTUP
SystemState PreviousState = STARTUP
2. Main Control Logic
⚠️ CONCEPTUAL PSEUDOCODE - PROFESSIONAL IMPLEMENTATION REQUIRED
Input Processing and Conditioning:
// Temperature Input Processing - EXAMPLE ONLY
RawTempReading = AnalogInput(TempSensorChannel)
// CALIBRATION VALUES MUST BE FIELD DETERMINED
RoomTemp = (RawTempReading * TempScale) + TempOffset
// Low-pass filter for temperature stability
// FILTER CONSTANT TO BE OPTIMIZED
FilteredTemp = (FilteredTemp * 0.9) + (RoomTemp * 0.1)
// Thermostat Interface - SYSTEM SPECIFIC
CoolingCall = DigitalInput(ThermostatY1)
FanCall = DigitalInput(ThermostatG)
CoolingSetpoint = AnalogInput(SetpointInput)
// Flow Measurement - CALIBRATION REQUIRED
FlowRate = AnalogInput(FlowMeterChannel) * FlowScale
// Valve Position Feedback - SYSTEM SPECIFIC
ValvePositionFeedback = AnalogInput(ValvePositionChannel)
// Manual Override
ManualOverride = DigitalInput(OverrideSwitch)
Primary State Machine - CONCEPTUAL LOGIC:
// Main state machine execution - EXAMPLE IMPLEMENTATION
FUNCTION StateController():
// Increment timers
SystemStartupTimer += 1
StateTimer += 1
// Check for manual override
IF ManualOverride = TRUE THEN
CurrentState = MANUAL_OVERRIDE
RETURN
END_IF
// Check for system faults
IF SystemFault = TRUE THEN
CurrentState = FAULT
RETURN
END_IF
// Startup sequence - TIME TO BE OPTIMIZED
IF SystemStartupTimer < 30 THEN
CurrentState = STARTUP
RETURN
END_IF
// Normal state machine logic - PARAMETERS TO BE TUNED
CASE CurrentState:
STARTUP:
IF SystemStartupTimer >= 30 THEN
CurrentState = NORMAL_COOLING
StateTimer = 0
END_IF
NORMAL_COOLING:
// DEADBAND VALUES TO BE FIELD OPTIMIZED
IF FilteredTemp < (CoolingSetpoint - CoolingDeadband) AND
StateTimer >= MinimumRuntime THEN
CurrentState = TRANSITION_TO_BYPASS
TransitionTimer = 0
StateTimer = 0
END_IF
BYPASS_COOLING:
// TRIGGER POINTS TO BE OPTIMIZED
IF FilteredTemp > (CoolingSetpoint + 1.0) AND
StateTimer >= MinimumRuntime THEN
CurrentState = TRANSITION_TO_NORMAL
TransitionTimer = 0
StateTimer = 0
END_IF
TRANSITION_TO_BYPASS:
TransitionTimer += 1
// TRANSITION TIME TO BE OPTIMIZED
IF TransitionTimer >= 300 THEN // 5 minutes maximum
CurrentState = BYPASS_COOLING
StateTimer = 0
END_IF
TRANSITION_TO_NORMAL:
TransitionTimer += 1
IF TransitionTimer >= 300 THEN
CurrentState = NORMAL_COOLING
StateTimer = 0
END_IF
FAULT:
// Remain in fault state until manual reset
IF FaultReset = TRUE THEN
SystemFault = FALSE
CurrentState = STARTUP
SystemStartupTimer = 0
END_IF
MANUAL_OVERRIDE:
IF ManualOverride = FALSE THEN
CurrentState = NORMAL_COOLING
StateTimer = 0
END_IF
END_CASE
// State change logging
IF CurrentState != PreviousState THEN
LogStateChange(PreviousState, CurrentState)
PreviousState = CurrentState
END_IF
END_FUNCTION
Valve Control Algorithm - CONCEPTUAL:
FUNCTION ValveController():
// Calculate target valve position
CASE CurrentState:
STARTUP, NORMAL_COOLING:
TargetPosition = 0.0 // Full flow through heat pump
BYPASS_COOLING:
TargetPosition = 100.0 // Full bypass
TRANSITION_TO_BYPASS:
TargetPosition = (TransitionTimer / 300.0) * 100.0
TRANSITION_TO_NORMAL:
TargetPosition = 100.0 - ((TransitionTimer / 300.0) * 100.0)
MANUAL_OVERRIDE:
TargetPosition = ManualPositionSetting
FAULT:
TargetPosition = 0.0 // Fail-safe to normal cooling
END_CASE
// Smooth valve positioning with ramping
// RAMP RATE TO BE OPTIMIZED TO PREVENT WATER HAMMER
PositionError = TargetPosition - ValvePosition
IF ABS(PositionError) > 2.0 THEN
IF PositionError > 0 THEN
ValvePosition += RampRate
IF ValvePosition > TargetPosition THEN
ValvePosition = TargetPosition
END_IF
ELSE
ValvePosition -= RampRate
IF ValvePosition < TargetPosition THEN
ValvePosition = TargetPosition
END_IF
END_IF
ELSE
ValvePosition = TargetPosition
END_IF
// Output valve command
AnalogOutput(ValveCommandChannel, ValvePosition)
END_FUNCTION
3. Safety and Fault Detection
⚠️ SAFETY CRITICAL - PROFESSIONAL REVIEW REQUIRED
Comprehensive Fault Detection - CONCEPTUAL:
FUNCTION FaultDetection():
SystemFault = FALSE
FaultCode = ""
// Temperature sensor fault detection
// LIMITS TO BE DETERMINED BY SYSTEM REQUIREMENTS
IF RawTempReading < -50.0 OR RawTempReading > 200.0 THEN
SystemFault = TRUE
FaultCode = "TEMP_SENSOR_FAULT"
RETURN
END_IF
// Valve position fault detection
// TOLERANCES TO BE FIELD DETERMINED
IF ABS(ValvePosition - ValvePositionFeedback) > 10.0 THEN
PositionFaultTimer += 1
IF PositionFaultTimer > 120 THEN // TIME TO BE OPTIMIZED
SystemFault = TRUE
FaultCode = "VALVE_POSITION_FAULT"
RETURN
END_IF
ELSE
PositionFaultTimer = 0
END_IF
// Flow fault detection
// MINIMUM FLOW TO BE DETERMINED BY ENGINEER
IF FlowRate < MinimumFlow AND CurrentState != STARTUP THEN
FlowAlarmTimer += 1
IF FlowAlarmTimer > 60 THEN // DELAY TO BE OPTIMIZED
SystemFault = TRUE
FaultCode = "LOW_FLOW_FAULT"
RETURN
END_IF
ELSE
FlowAlarmTimer = 0
END_IF
// Communication timeout fault
// TIMEOUT VALUES TO BE SYSTEM SPECIFIC
IF CommunicationTimeout > 300 THEN
SystemFault = TRUE
FaultCode = "COMMUNICATION_FAULT"
RETURN
END_IF
END_FUNCTION
Backup Control Logic - SAFETY CRITICAL:
FUNCTION BackupControl():
// Backup control when temperature sensor fails
IF FaultCode = "TEMP_SENSOR_FAULT" THEN
// Use thermostat calls as backup indication
// LOGIC TO BE VERIFIED WITH THERMOSTAT INTERFACE
IF CoolingCall = TRUE THEN
CurrentState = NORMAL_COOLING
BypassEnabled = FALSE
ELSE
CurrentState = BYPASS_COOLING
BypassEnabled = TRUE
END_IF
END_IF
// Emergency bypass on critical faults
IF FaultCode = "VALVE_POSITION_FAULT" OR
FaultCode = "LOW_FLOW_FAULT" THEN
ValvePosition = 0.0 // Fail-safe to normal cooling position
BypassEnabled = FALSE
END_IF
END_FUNCTION
4. Advanced Control Features
⚠️ CONCEPTUAL FEATURES - OPTIMIZATION REQUIRED
Adaptive Control Algorithm - EXAMPLE:
// Historical data structure - CONCEPTUAL
STRUCT HistoricalRecord:
DINT Timestamp
REAL RoomTemp
REAL OutdoorTemp
REAL ValvePosition
REAL EnergyUsage
SystemState State
END_STRUCT
// DATA STORAGE CAPACITY TO BE DETERMINED
ARRAY[0..1440] OF HistoricalRecord DailyHistory
FUNCTION AdaptiveControl():
// Record current data
DailyHistory[CurrentMinute].Timestamp = SystemTime
DailyHistory[CurrentMinute].RoomTemp = FilteredTemp
DailyHistory[CurrentMinute].ValvePosition = ValvePosition
DailyHistory[CurrentMinute].State = CurrentState
// Weekly analysis for deadband optimization
// ANALYSIS ALGORITHM TO BE DEVELOPED
IF DayOfWeek = SUNDAY AND Hour = 0 AND Minute = 0 THEN
OptimalDeadband = AnalyzeWeeklyPerformance()
// LIMITS TO BE FIELD DETERMINED
IF OptimalDeadband >= 1.0 AND OptimalDeadband <= 4.0 THEN
CoolingDeadband = OptimalDeadband
END_IF
END_IF
// Seasonal adjustments - VALUES TO BE OPTIMIZED
CASE MonthOfYear:
6, 7, 8: // Summer months
CoolingDeadband = CoolingDeadband * 0.8
12, 1, 2: // Winter months
CoolingDeadband = CoolingDeadband * 1.2
DEFAULT:
// Spring/Fall - no adjustment
END_CASE
END_FUNCTION
Predictive Control - CONCEPTUAL:
FUNCTION PredictiveControl():
// Calculate temperature trend
// TREND CALCULATION TO BE OPTIMIZED
TempTrend = (FilteredTemp - TempHistory10MinAgo) / 10.0
PredictedTemp = FilteredTemp + (TempTrend * 30.0)
// Preemptive state changes
// PREDICTION PARAMETERS TO BE TUNED
IF CurrentState = BYPASS_COOLING AND
PredictedTemp > (CoolingSetpoint + 0.5) THEN
EarlyTransitionFlag = TRUE
TransitionAdvanceTime = 300 // TIME TO BE OPTIMIZED
END_IF
// Load prediction based on time and weather
// SCHEDULE TO BE CUSTOMIZED FOR BUILDING
IF TimeOfDay >= 14 AND TimeOfDay <= 18 THEN
PredictedLoad = HIGH
MinimumRuntime = 900
ELSE
PredictedLoad = NORMAL
MinimumRuntime = 600
END_IF
END_FUNCTION
5. Building Integration and Optimization
⚠️ BUILDING-SPECIFIC CUSTOMIZATION REQUIRED
Building-Wide Load Management - CONCEPTUAL:
FUNCTION BuildingOptimization():
// Calculate building load factor
// COMMUNICATION SYSTEM TO BE IMPLEMENTED
ActiveCoolingUnits = CountActiveUnits()
TotalUnits = GetTotalUnits()
BuildingLoadFactor = ActiveCoolingUnits / TotalUnits
// Adjust control parameters based on building load
// FACTORS TO BE FIELD OPTIMIZED
IF BuildingLoadFactor > 0.8 THEN
LocalCoolingDeadband = CoolingDeadband * 0.9
MinimumRuntime = 600
ELSIF BuildingLoadFactor < 0.3 THEN
LocalCoolingDeadband = CoolingDeadband * 1.1
MinimumRuntime = 900
ELSE
LocalCoolingDeadband = CoolingDeadband
MinimumRuntime = 600
END_IF
// Coordinate with building pump control
// INTERFACE TO BE DESIGNED FOR SPECIFIC SYSTEM
IF BuildingPumpVFD_Available = TRUE THEN
TotalBuildingFlow = SUM(AllUnitFlows)
PumpSpeedCommand = FlowController(TotalBuildingFlow, DesiredBuildingFlow)
// Communication method to be determined
ModbusWrite(PumpSpeedRegister, PumpSpeedCommand)
END_IF
END_FUNCTION
Energy Calculation and Reporting - ESTIMATES ONLY:
FUNCTION EnergyCalculation():
// Calculate instantaneous energy usage
// VALUES TO BE MEASURED AND CALIBRATED
IF CurrentState = BYPASS_COOLING THEN
CurrentEnergyUsage = BypassEnergyUsage
ELSE
CurrentEnergyUsage = NormalEnergyUsage
END_IF
// Accumulate daily energy totals
DailyEnergyTotal += CurrentEnergyUsage
// Calculate energy savings - ESTIMATES ONLY
EstimatedNormalUsage = NormalEnergyUsage * 1440
DailyEnergySavings = EstimatedNormalUsage - DailyEnergyTotal
// Calculate efficiency metrics
IF DailyEnergyTotal > 0 THEN
EfficiencyRatio = DailyEnergySavings / EstimatedNormalUsage * 100
ELSE
EfficiencyRatio = 0
END_IF
END_FUNCTION
6. Communication and Data Management
⚠️ SYSTEM-SPECIFIC IMPLEMENTATION REQUIRED
BACnet Communication - EXAMPLE IMPLEMENTATION:
// BACnet object definitions - CONCEPTUAL
BACnetObject AnalogInput_RoomTemp:
ObjectIdentifier = (ANALOG_INPUT, 1)
ObjectName = "Room Temperature"
PresentValue = FilteredTemp
Units = DEGREES_FAHRENHEIT
BACnetObject AnalogValue_CoolingSetpoint:
ObjectIdentifier = (ANALOG_VALUE, 1)
ObjectName = "Cooling Setpoint"
PresentValue = CoolingSetpoint
Units = DEGREES_FAHRENHEIT
BACnetObject MultiStateInput_SystemState:
ObjectIdentifier = (MULTI_STATE_INPUT, 1)
ObjectName = "System State"
PresentValue = CurrentState
StateText = ["Startup", "Normal Cooling", "Bypass Cooling",
"Transition to Bypass", "Transition to Normal",
"Fault", "Manual Override"]
BACnetObject AnalogOutput_ValvePosition:
ObjectIdentifier = (ANALOG_OUTPUT, 1)
ObjectName = "Valve Position"
PresentValue = ValvePosition
Units = PERCENT
BACnetObject BinaryValue_BypassEnable:
ObjectIdentifier = (BINARY_VALUE, 1)
ObjectName = "Bypass Enable"
PresentValue = BypassEnabled
Modbus RTU Communication - EXAMPLE MAPPING:
// Modbus register mapping - SYSTEM SPECIFIC
ModbusRegister[40001] = FilteredTemp * 10 // 0.1°F resolution
ModbusRegister[40002] = CoolingSetpoint * 10 // 0.1°F resolution
ModbusRegister[40003] = CurrentState // State number
ModbusRegister[40004] = ValvePosition * 10 // 0.1% resolution
ModbusRegister[40005] = FlowRate * 10 // 0.1 GPM resolution
ModbusRegister[40006] = BypassEnabled // Boolean
ModbusRegister[40007] = SystemFault // Boolean
ModbusRegister[40008] = DailyEnergySavings // kWh
Data Logging System - CONCEPTUAL:
FUNCTION DataLogging():
// Continuous data logging every minute
IF Second = 0 THEN // Top of each minute
LogRecord.Timestamp = SystemTime
LogRecord.RoomTemperature = FilteredTemp
LogRecord.CoolingSetpoint = CoolingSetpoint
LogRecord.SystemState = CurrentState
LogRecord.ValvePosition = ValvePosition
LogRecord.FlowRate = FlowRate
LogRecord.EnergyUsage = CurrentEnergyUsage
LogRecord.BypassEnabled = BypassEnabled
LogRecord.SystemFault = SystemFault
// Write to log buffer
WriteLogRecord(LogRecord)
// Manage log buffer size
// STORAGE CAPACITY TO BE DETERMINED
IF LogBuffer.Count > 10080 THEN // 1 week of minute data
ArchiveOldestRecord()
DeleteOldestRecord()
END_IF
END_IF
END_FUNCTION
7. User Interface and Diagnostics
⚠️ INTERFACE DESIGN TO BE CUSTOMIZED
Display System - CONCEPTUAL:
FUNCTION UpdateDisplay():
// Main display screen - LAYOUT TO BE DESIGNED
Display.Line1 = "Room: " + FormatTemp(FilteredTemp) + "°F"
Display.Line2 = "Setpoint: " + FormatTemp(CoolingSetpoint) + "°F"
Display.Line3 = "State: " + StateNames[CurrentState]
Display.Line4 = "Valve: " + FormatPercent(ValvePosition) + "%"
// Status indicators - HARDWARE SPECIFIC
LED_Normal = (CurrentState = NORMAL_COOLING)
LED_Bypass = (CurrentState = BYPASS_COOLING)
LED_Fault = (SystemFault = TRUE)
LED_Manual = (ManualOverride = TRUE)
// Energy savings display - VALUES TO BE CALIBRATED
IF DailyEnergySavings > 0 THEN
Display.Line5 = "Saved: " + FormatEnergy(DailyEnergySavings) + " kWh"
ELSE
Display.Line5 = "Cooling Active"
END_IF
END_FUNCTION
Alarm Management - SYSTEM SPECIFIC:
STRUCT AlarmDefinition:
STRING AlarmCode
INT Priority // 1=Critical, 2=Warning, 3=Info
STRING Message
BOOL Active
DINT ActivationTime
END_STRUCT
// ALARM DEFINITIONS TO BE CUSTOMIZED
ARRAY[1..10] OF AlarmDefinition SystemAlarms = [
{"TEMP_SENSOR", 1, "Temperature sensor fault", FALSE, 0},
{"VALVE_FAULT", 1, "Valve position error", FALSE, 0},
{"LOW_FLOW", 2, "Low water flow detected", FALSE, 0},
{"HIGH_TEMP", 2, "Room temperature high", FALSE, 0},
{"COMM_FAULT", 3, "Communication timeout", FALSE, 0},
{"POWER_FAIL", 1, "Power supply fault", FALSE, 0},
{"SENSOR_DRIFT", 2, "Sensor calibration drift", FALSE, 0},
{"MANUAL_MODE", 3, "Manual override active", FALSE, 0},
{"MAINTENANCE", 3, "Maintenance required", FALSE, 0},
{"CONFIG_ERROR", 1, "Configuration error", FALSE, 0}
]
FUNCTION AlarmProcessing():
FOR i = 1 TO 10 DO
// Check alarm conditions - THRESHOLDS TO BE SET
CASE SystemAlarms[i].AlarmCode:
"TEMP_SENSOR":
SystemAlarms[i].Active = (FaultCode = "TEMP_SENSOR_FAULT")
"VALVE_FAULT":
SystemAlarms[i].Active = (FaultCode = "VALVE_POSITION_FAULT")
"LOW_FLOW":
SystemAlarms[i].Active = (FaultCode = "LOW_FLOW_FAULT")
"HIGH_TEMP":
// THRESHOLD TO BE FIELD DETERMINED
SystemAlarms[i].Active = (FilteredTemp > CoolingSetpoint + 5.0)
"COMM_FAULT":
SystemAlarms[i].Active = (FaultCode = "COMMUNICATION_FAULT")
"MANUAL_MODE":
SystemAlarms[i].Active = (ManualOverride = TRUE)
END_CASE
// Process alarm activation
IF SystemAlarms[i].Active AND SystemAlarms[i].ActivationTime = 0 THEN
SystemAlarms[i].ActivationTime = SystemTime
// Take action based on priority
// NOTIFICATION SYSTEM TO BE IMPLEMENTED
CASE SystemAlarms[i].Priority:
1: //
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