Honeywell W7750A Modes of Operation, Dirty Filter Monitor, Indoor Air Quality IAQ Override

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EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER

Dirty Filter Monitor

The air filter in the air handler can be monitored by the W7750 and an alarm is issued when the filter media needs replacement. The two methods of monitoring the filter are:

1.Connecting a differential pressure switch to a digital input on the W7750A or W7750B,C.

2.Wiring a 2 to 10V differential pressure sensor to a voltage input on the W7750B,C. If the analog input sensor is used, its measured value 0 to 5 inw (0 to 1.25 kPa) is compared to a user-selectable setpoint (FltrPressStPt— valid range: 0 to 5 inw (0 to 1.25 kPa)), and the Dirty Filter alarm is issued when the pressure drop across the filter exceeds the setpoint.

Indoor Air Quality (IAQ) Override

The Excel 10 W7750 Controller provides IAQ ventilation control using one of two different methods of detecting poor air quality. The first is with an IAQ switch device connected to a digital input on the W7750 Controller, where a contact closure indicates poor air quality, and initiates the IAQ Override mode. The device can detect poor air quality using any desired measure such as CO2, VOC, CO, etc. The second method, which is only available on the W7750B,C, is through an analog input that connects to a CO2 sensor (2 to 10V). The measured value of CO2 from this sensor (0 to 2000 PPM) is compared to the setpoint (IAQSetpt). When the CO2 level is higher than the setpoint (800 PPM adjustable), the

IAQ Override is initiated. The IAQSetpt hysteresis is 50 PPM, IAQ Override is deactivated at a CO2 level less than 50 PPM below setpoint.

The effect of initiating the IAQ Override mode is that the economizer dampers are allowed to open above the standard minimum position setting to allow more fresh air to enter the building. See Appendix B— Sequences of Operation, for further control details.

Smoke Control

The Excel 10 W7750 Controller supports smoke-related control strategies that are initiated either via a network command (DestEmergCmd) or from a local (physically connected) smoke detector digital input. The details of the W7750 smoke-related control operation are described in Appendix B— Sequences of Operation.

Freeze Stat

A freeze stat can be monitored by the W7750 and issue a freeze stat alarm indicating the CVAHU is in danger of freezing its coil. The details of the W7750 freeze stat related control operation are described in Appendix B— Sequences of Operation.

Modes of Operation

The possible modes of operation for the W7750 Controller are listed in Table 5.

Table 5. Modes Of Operation For The Excel 10 W7750 Controller .

 

 

 

Mode

Description

Events causing a controller to switch to this mode

 

 

 

Effective Occupancy (User Address: StatusOcc)

 

 

 

 

OCCUPIED

Controller is in Occupied mode

Any of the following: Network input (DestSchedOcc) containing a

 

 

time-of-day schedule flag from either the Excel 10 Zone Manager or an

 

 

LONWORKS Bus Controller; Time Clock DI, Occupancy Sensor DI; or

 

 

from Network input (DestManMode) for manual override to OCC mode.

 

 

DestManMode has the highest priority, followed by the Time Clock DI,

 

 

and then DestSchedOcc.

 

 

 

STANDBY

Controller is in Standby mode

Either: (A) Network input (DestSchedOcc) containing a time-of-day

 

 

schedule flag from the Excel 10 Zone Manager or other LONWORKS

 

 

Bus node is STANDBY, or (B) Network input (DestSchedOcc) is

 

 

OCCUPIED and the Occupancy Sensor DI is UNOCCUPIED.

 

 

 

UNOCCUPIED

Controller is in Unoccupied mode

Network input (DestSchedOcc) containing a time-of-day schedule flag

 

 

from the Excel 10 Zone Manager or LONWORKS Bus, or the network

 

 

input DestManOcc has a value of UNOCCUPIED.

 

 

 

BYPASS

Controller is in Occupied mode through

This mode is derived from the schedule occupancy (DestSchedOcc)

OCCUPIED

a Bypass command

having a state of UNOCCUPIED and a manual request for occupancy

 

 

from one of three sources. Two of these are signals originated external

 

 

to the unit, and received by DestManOcc and DestBypass. The third

 

 

source for an occupancy request is from an override button located on

 

 

a wall module. These three sources are arbitrated in a scheme

 

 

determined by the configuration parameter (Network Wins or Last-in

 

 

Wins from OvrdPriority).

 

 

 

Override Modes (User Address: StatusOvrd)

 

 

 

 

OCCUPIED

Controller occupancy mode was

Network input (DestManOcc) containing a time-of-day schedule

 

overridden to Occupied mode

override signal of OCCUPIED from the Excel 10 Zone Manager or

 

 

other LONWORKS Bus device.

 

 

 

STANDBY

Controller occupancy mode was

Network input (DestManOcc) containing a time-of-day schedule

 

overridden to Standby mode

override signal of STANDBY from the Excel 10 Zone Manager or other

 

 

LONWORKS Bus device.

 

 

 

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Contents Excel General Considerations W7750 Controllers Appendices72-2958 74-2958 List of Figures74-2958 Setpoint ramping parameters with ramp rate calculationList of Tables Typical system overview Description of DevicesControl Provided Control ApplicationForm No Title Products CoveredOrganization of Manual Applicable LiteratureAgency Listings Product NamesAbbreviations and Definitions Controllers ConstructionDI-1 W7750APerformance Specifications PowerSpecial Note for the W7750B,C Unit Specified Space Temperature Sensing Range CPUMemory Capacity Excel 10 W7750C Constant Volume AHU Controller Jack Lonmark Functional Profile DIN rail adaptersAnalog Inputs Inputs/OutputsDigital Inputs Triac Outputs on the W7750B,C Models onlyDigital Outputs T7770C Wall ModulesDuct Sensor T7770A1006T7560A,B construction in in. mm General ConfigurationsConfiguration Options Summary For W7750A,B,C Controllers Modulating HEATING/COOLING Control Allowable Heating and Cooling Equipment ConfigurationsStaged HEATING/COOLING Control Heat Pump ControlPneumatic Actuator Control Economizer ControlMIXED-OUTPUT-TYPE Control Occupancy SensorWindow Open/Closed Digital Input Wall Module OptionsSmoke Control Modes of OperationDirty Filter Monitor Indoor Air Quality IAQ OverrideAssigned OFF ModeDisabled NotStep No Description OverviewPlan the System Determine Other Bus Devices RequiredLonworks Bus Layout Lay Out Communications and Power WiringExcel VAV Cvahu Power Wiring Power Budget Calculation ExampleDeviceVA Information Obtained from Line Loss VA Ratings For Transformer Sizing Device DescriptionML6161A/B Damper Actuator, 35 lb-in R8242A Contactor ML7984B PWM Valve ActuatorNema class 2 transformer voltage output limits Power wiring details for one Excel 10 per TransformerGeneral Considerations Prepare Wiring DiagramsW7750 Controllers Terminal Terminal Number Description Factory Default Digital OutputsConstant Volume AHU Controller ML6161 Floating Actuator COM CCW Load Controller Power Heat Wall Economizer Damper PWM Actuator Power Signal W7750C Constant Pneumatic transducer to W7750B,C Shown, see triangle note Lonworks Bus Termination ModuleBrown Orange Order Equipment Lonworks Bus termination wiring optionsT7770 and T7560 Wall Modules Honeywell Logo T7770D1018Sensor with Bypass/LED and Lonworks Jack Accessories Sensors AccessoriesEchelon Based Components and Parts Cabling Configure ControllersTroubleshooting Troubleshooting Excel 10 Controllers and Wall ModulesAlarms Excel 10 AlarmsResistance Value ohms W7750 Controller Status LED Broadcasting the Service MessageSensor Calibration Appendix A. Using E-Vision to Commission a W7750 ControllerSetting the Pid Parameters T7770C,D Wall Module Bypass Pushbutton and Override LEDAppendix B. Sequences of Operation Common Operations IAQ Option Room Temperature Sensor RmTempHeating EconomizerBypassTime Bypass Mode StatusOvrd and StatusLedRemote Setpoint RmtStptPot Setpoint Limits LoSetptLim and HiSetptLimBypass Occupied Continuous Unoccupied ModeOccupancy Mode and Manual Override Arbitration Not AssignedSetpoint Ramping Recovery Ramping for Heat Pump SystemsTime Clock OccTimeClock Schedule Master SchedMasterDemand Limit Control DLC Window Sensor StatusWndwSmoke Control FAN OperationTemperature Control Operations See for a diagram of a typical W7750 UnitDirty Filter Monitor Three Stages Staged Cooling ControlONE Stage TWO StagesOutdoor AIR Lockout of HEATING/COOLING Cascade Control of Modulating COOLING/HEATINGSeries 60 Modulating Control Pulse Width Modulating PWM ControlDischarge AIR LOW Limit Control Economizer ENABLE/DISABLE ControlIndoor AIR Quality IAQ Override Freeze StatStatus Points Address Input Output Points AddressControl Parameters Address Energy Management Points AddressMappable User Addresses and Table Number Enthalpy Relative TemperatureAir Flow CO2 ConcentrationEnumerated values are shown Application reset therefore, these points canPlaced in manual mode through a menu Valid states and the correspondingComments DefaultInput/Output Points NvName Field NameOccsensor Unuseddi NciIoSelect DigitalIn1Occsensor Shcedmasterin 255 NciIoSelect DigitalIn2COOLSTAGE4 COOLSTAGE1COOLSTAGE2 COOLSTAGE3Siinvalid SixtyfiftyPPM Siinvalid FalseTrue OccSensr NvoIO EconEnSw NvoIO EconEnableInPosition when poor indoor air quality is detected StatusDI3 NvoIO UbDigitalInNvName Default CommentsControl Parameters MaxClRamp, OdTempMaxClRamp, OdEnthalpyEnableMaxClRamp NciAux1SetPt UbMaxClRampS0 Degrees F/Hr MinClRamp NciAux1SetPt UbMinClRampS0 Degrees F/HrPPM GainHeatProp NciAux2SetPt UbKpHeatS2 Degrees F Degrees C Discharge air temperature cascade control loopGainCoolProp NciAux2SetPt UbKpCoolS2 Degrees F Degrees C Gain for the cooling control loopEnergy Management Points Network variable input fails Refer to WSHPEnable.valueNviFree1 Value Auxiliary functions. nviFree1 controls the FREE1OUT255 SrcTimeClkCt NvoTimeClk Value NviTimeClk ValueDestTimeClk NviTimeClk State Refer to nviTimeClk.valueStatus Points Bit Offset = InvalidSetPtAlrm Alarmbit1Bit Offset = SensorFailAlrm Bit Offset = FrostProtectAlrmUpdateallfields NoalarmNodedisabled SmokealarmCool DisabledmodeStartupwait HeatStatusManOcc NvoData1 NetManOcc StatusEconEn NvoData1 EconEnableAir flow switch is configured NciAux1SetPts.ubOdEnthalpyEnableS2For both heating or cooling HeatStgsOn NvoData1 HeatStagesOnAuxiliary heating stages are turned on CoolStgsOn NvoData1 CoolStagesOnMonitorSw NvoData1 MonSwitch Is 1, the algorithm controls as per the settings foundNciConfig.SmokeControl Controller mode is switched to FreezeprotectDischargetempfield BypasstimerfieldTempcontrolptfield SpacetempfieldUbinvalid Bit Offset = Temperature SetPtError NvoError Errorbit0 StatusError NvoError Errorbit0SpaceTempError NvoError Errorbit0Bit Offset = SpaceCO2Error NvoError Errorbit1 NvoError Errorbit1Bit Offset = RtnEnthalpyError NvoError Errorbit1 Are disabled as if the sensor was not configuredBit Offset = NvByPassError NvoError Errorbit3 Bit Offset = NvWindowError NvoError Errorbit2Bit Offset = NvDlcShedError NvoError Errorbit2 Bit Offset = NvTodEventError NvoError Errorbit3Calibration Points CfglocalCfgexternal CfgnulConfiguration Parameters False True UseRaTempCtl NciConfig DisMinHtTime NciConfig DisableHeatMinTimeDisMinClTime NciConfig DisableCoolMinTime CascCntrl NciConfig CascadeControlBypassonly Last NETOffset Absolutemiddle None NormalLonmark /Open System Points Hvacoff HvacautoHvacheat Hvacmrngwrmup Hvacprecool Hvaccool Hvacnightpurge HvacnulSrcRmTemp NvoSpaceTemp Degrees F 74-2958 100DestRmTemp NviSpaceTemp Degrees F SNVTtempp 14 toHvacauto Hvacnul HvacmrngwrmupHvactest Alarmnotifydisabled NvoStatus Unabletomeasure NvoStatus Electricalfault103 NvoStatus Inalarm 255 Not configured 74-2958Swon SrcEconEnCt NvoEcon Value On other nodes. If the economizer function is configured byCorresponding economizer function is not enabled because SrcEconEnable NvoEcon StateDirect Access And Special Points OFF Data Share Points Mapped points = number of mapped points per Excel Approximate Memory Size Estimating Procedure=using One-to-Many and not using points = including mapped points and others forSensor Use Sensor Resistance Versus Temperature Resistance OhmsResistance Sensors Sensor TypeAbove and Below Setpoint Resistance Ohms Offset Setpoint TemperatureDirect Setpoint Temperature T7770B,C 10K ohm setpoint potentiometer RelativeVoltage/Current Sensors Sensor Voltage Versus Humidity Humidity PercentageSensor Voltage Versus Humidity Relative Humidity Percentage 113 74-2958 Sensor Current Versus Enthalpy volts Enthalpy mAT7242 or equivalent 74-2958 114MAmAmAmA AmA mA mA Sensor Voltage Versus Input Voltage To A/D Voltage to A/D 50.0.13 Sensor Voltage Vdc Versus Pressure InwPressure Inw kPa Sensor Voltage Vdc Inw
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