AHU

AirHandlingUnits

3

3 Air Handling UnitsGeneral 3 3

Fresh Air Plant 3 6

Return Temperature Control 3 8Supply and Return Sensors 3 10

Variable Supply Temp. Control 3 12VAV Plant 3 13Reheat Terminals 3 14

Slaving AHU’s 3 16

AHU Submodules 3 19Multi Stage Outputs 3 20Analogue Actuators 3 21DeHumidification 3 22PreHeater 3 24Heat Recovery 3 26Mixing Dampers 3 28Static Pressure 3 31Humidity 3 32Fan Changeover 3 33

Extract Fans 3 35AHU Extract Fans 3 36Non AHU Extract Fans 3 37Toilet Extract 3 38

Examples - AHU Systems1 Fresh Air Plant 3 412 Return Air Control 3 473 Large Building AHU’s 3 53

3 2 Air Handling Units

General•Air Handling Units are controlled by AHU Controllers.

•Air Handling Units are Demand Driven from the zones of thebuilding that they serve; you will need at least one Zone Controller in order to make the AHU run.

•AHU Controllers may need Submodules registered to them toextend their control abilities to match your application; see page 3 19.

•The AHU Controller may contain the System HousekeepingFunction; see System Design section 7.

•Three types of AHU Controller are available for:• Constant Supply Temperature - Fresh Air Plant• Constant Return Temperature - Return Air Plant• Variable Supply Temperature - Variable Supply Air

AHU Controller

Zone Controller

Zone Controller

Zone Controller

Air Handling Units

Air Handling Units 3 3

Outputs•Switching outputs are provided for Heating and Cooling, 2

relays for each. The outputs are either configured to drive a valve - wet battery, or as 2-stage outputs for an electric or direct-fired gas battery

Valves•for wet batteries, valves are Raise / Lower type;

if 0-10V DC valves are used, you need an additional ActuatorSubmodule registered to the AHU Controller to give 0-10V DC outputs for heating and cooling. Note - 0-10V DC valves give no control benefits over Raise/Lower valves use ACT/DIN/AOP/921

•choose the product variant to suit your battery types; an AHU/../../WW will have a wet heating battery, and a wet cooling battery. An AHU/../../WE will have a wet heating battery and a single or 2-stage cooling battery

Fans•relay outputs are provided for Supply and Extract Fans. If

isolation dampers are fitted, use these outputs to drive the damper, and use an end switch on the damper to start the fan. This ensures the damper is open before the fan can start

Inputs•2 inputs are provided for Volt-free contacts; the first is for

Fan Status monitoring, usually a pressure switch, which can be used to shut down the AHU upon Fan failure, or just raise an alarm

•a second input is provided for Filter Blocked monitoring; thiscan be set to raise an alarm. If you have 2 filters, common the signals to provide a single Filter Blocked contact.

Occupancy Times•are determined by the Zone Controllers registered to the

AHU Controller; the AHU Controller has no Occupancy Times itself.

•AHU/DIN/FRE/.. will have one or more Zone Controllers withOccupancy Demand Interconnects to the AHU Controller.

Any one of the Zones going into Occupation will cause the plant to run, which is what is needed for a Fresh Air system. The AHU will not normally run during Optimum Start or Fabric Protection because it is taking no part in the heating orcooling of the space.

3 4 Air Handling Units

•AHU Controller can be Setpoint Supervised from a Zone Controller. Set SPTY=4 in AHU Controller.

•AHU/DIN/RET/.. usually has a dedicated Zone Controller which manages the AHU Occupancy Times using OccupancyDemand, or both Times and Return Air Setpoint using Setpoint Supervision. The plant will run during Occupancy, and also during periods of Optimum Start and Fabric Protection because it is the sole form of heating and cooling for the space.

•AHU/DIN/SUP/.. will have one or more Zone Controllers with Energy Demand Interconnects to the AHU Controller. Any one of the Zones going into Occupation will cause the plant to run; it will also run during periods of Optimum Startand Fabric Protection because it is the sole form of heating and cooling for the space.

Fabric Protection•Zone Controller will control space to Non-Occupied Setpoint

during Non-Occupancy, to protect the building fabric against condensation damage

•use of Intelligent T+RH sensor allows RH-based Fabric Protection - use SEN/PTR/TRH/005See Zone Controller Data Sheet for full information

Night Cooling•the fans can be used to draw cool night air into the building

in order to pre-cool the space prior to occupation. This feature requires that a sensor is wired to the Return Air terminals on the AHU Controller - a sensor located somewhere in the space is better than a duct sensor for this application, as it gives a better reading when the fans are stopped.

Product Codes and Type SettingsThe Type of AHU that is required Fresh Air, Supply Air etc is normally specified as part of the Product Order Code.However the Type of AHU can be freely altered by setting the SPTY Parameter in the Module.

Air Handling Units 3 5

Fresh Air PlantConstant Supply Temperature

•the most common application, for Tempered Fresh Air supply; no temperature control of the space - this is done by local radiators, fan coils etc.

Uses AHU/DIN/FRE/... Supply air sensor must be fitted, AHU will not run without it.

Fresh Air Plant AHU

3 6 AHU’s Fresh Air Plant

AHU

Zone

Fan Coil

Fan Coil

Fan Coil

AHU’s Fresh Air Plant 3 7

For Fresh Air Plant, the AHU is driven ON wheneverany of the Zones is in occupancy, using theOccupancy Demand Interconnect. AHU SPTY = 3

AHU setpoint is set from one of theZones when SPTY = 4 in AHU.

Fresh Air Plant, Constant Supply Temperature Control

Fresh Air Plant, Constant Supply Temperature Control

Setpoint Supervision andOccupancy Demand from ZoneControllers

Occupancy Demand fromZone Controllers

Return Temperature ControlConstant Return Temperature

•for heating or heating/cooling of a space based on a single point measurement, either in the return air duct, or a wall-mounted sensor or average/minimum/maximum of several sensor values. Uses AHU/DIN/RET/... AHU’s run to Time Schedule held in Zone Controller. Controls to Return Air Setpoint when Zone in OccupancyAHU can be Setpoint Supervised by Zone Controller

AHU Plant with Return Air Temperature Control

3 8 AHU’s Return Temperature Control

AHU

Zone

Return

Supply

Extract

Supply

Return Air - Occupancy Control

Return Air - Setpoint Control

AHU’s Return Temperature Control 3 9

The Zone Controller adjusts the Setpoint anddetermines the Occupancy Times for both AHU’s

AHU’s will run if any of the Zones is in OccupancyAHU 1 causes AHU 2 to run using Occupancy DemandInterconnect

SensorsCascade Control

Return Air AHU’s require both Return and Supply Air Sensors.The control algorithm is that the AHU has two temperature control loops, one for Supply Air control and one for Return Air control. The Return Air control is cascaded onto the Supply Air setpoint which it can vary between the max. and min. Supply Air settings. This limits the temperature of the airsupplied from the AHU to avoid discomfort.

Returncontrolloop

Supplycontrolloop

Returnair

Supplyair

Controldemand tooutput drivers

Return airsetpoint

Supply airsetpoint

Supply Air Cascade Control for Return Air AHU’s For Setpoint Supervision from Zone set SPTY=1For Occupancy Demand from a Zone set SPTY=0

min. supply air

max. supply air

Cascade Control ofSupply and Return Air Control Loops

3 10 AHU’s Return Temperature Control

Returnair

Returncontrolloop

Controldemand tooutput driversReturn air

setpoint

Without Supply Air sensing:for Setpoint Supervision from Zone set SPTY=7for Occupancy Demand from Zone set SPTY=6

Return Air Only Control

The AHU can be used with Return Air temperature sensors only. In this case the Return air control loop directly drives thecontrol demand to the output drivers. This means that the supply air temperature is not limited by the control system.This type of control is often used with Direct Gas Fired plant.

Multiple Intelligent SensorsIntelligent Sensors can be used with AHU/DIN/RET, either Temperature or T+Rh or Zone Controllers, to provide the Return Air value. Up to 10 sensors or Zone Controllers are wired to the network and registered to a Monitoring Module MON/DIN/6R/002 which will calculate the Minimum, Maximum or Average of the readings. This processed value is passed on to the AHU Controller as a Return Air Temperature and Humidity if T+Rh sensors are used.

AHU’s Return Temperature Control 3 11

Control Using Return Air Only

3 12 AHU’s Variable Supply Temperature

AHU’s Variable Supply Temperature 3 13

Variable Supply Temperature•AHU Supply air Temperature is controlled to a setpoint that

is determined from inputs from other modules

•The main applications are for AHU Slaving and to feed Multiple ReHeat Terminal UnitsThese two applications are covered in the next pages

•AHU Slaving is where the slaved AHU controls its Supply Temperature to the same setpoint as the Master unit Supply

Temperature

•The Multiple ReHeat Terminal Units send their Heat and Cool Demands to the AHU Controller which are used to calculate the Supply Air Setpoint. The Setpoint is calculatedto minimise the amount of ReHeat while ensuring the Zonewith the highest Demand is just satisfied.

This has the effect of varying the Supply Air Temperature to give the best Energy Efficiency consistent with maintaining Control

•Supply Air Sensor must be fittedAHU will not run if Sensor is missing

Reheat Terminals•AHU controller supplies tempered air to a number of Reheat

terminal units

•Terminal units are each controlled by a fan coil controller

•Fan coils occupancy and setpoint are driven from Zone controllers - see Terminal Unit controls section for full details

•AHU Supply temperature varies to minimise the amount of Reheat required

•AHU must have Supply temperature sensor fitted or AHU will not run.

Supply plant

AHU ControllerVariable TemperatureSPTY = 2

ZoneController

Fan CoilController

Fan CoilController

Fan CoilController

Reheat Terminal Units

ZoneController

ZoneController


Heat and Cool Demandsto Boiler and Chiller plantthat supply AHU

Reheat Terminal Units

Interconnect Diagram Heat Demand toplant supplyingLPHW to reheats


Heat and CoolDemands vary SupplyAir Temperature fromAHU to minimise theamount of reheat

Slaving AHU’sAir Handling units can be slaved together. This means that they will supply air to the same Supply Air Setpoint.

This is particularly useful for a number of AHU’s in one large area. If they were all working independently on Return Air control they could end up fighting each other by supplying air at different temperatures.

With the AHU slaving feature, one AHU will control Return airand all will supply the same Supply air setpoint.

Supply Setpoint Slaving

Returncontrolloop

Supplycontrolloop

Returnair

Supplyair

Control Demandto output drivers

Return air setpointControl demand

Master AHU

Slave AHU SPTY = 5Control Demandto output drivers

Supplycontrolloop


Return Air Control Loop in Master AHU provides CascadeControl of Supply Air Setpoint in Master and Slave AHU’s

Supply AirSetpoint


MasterAHU

SlaveAHU

SlaveAHU


Master AHU Controls Return Air Temperature and sendsSupply Air Setpoint to Slave AHU’s


Return AirControl

SlaveAHU

SlaveAHU

CommonExtract

3 18 AHU’s

AHU SubmodulesAHU submodules can be added to any AHU Controller to extend its capability so that it can control more complex AHU Plant. The sections that follow show the different submodules and the applications that they handle.

Number of submodulesThe number of the various types of submodule that can be used with any one AHU Controller:1 Mixing Damper or Heat Recovery1 Preheater3 Intelligent Humidity and Temperature Sensors1 Humidity Controller2 Fan Changeover or Static Pressure

and any two from: AHU CascadeActuatorDessicant/Thermal Wheel

AHU’s Submodules 3 19

AHU Submodules

Intelligent Sensors and AHU Submodulesare registered to the AHU Controller

3 20 AHU’s Submodules

AHU Cascade submodulefor Multi Stage Outputs

•Main AHU Controller can have Raise Lower outputs for wet Heating Batteries or Staged outputs for Heat Pumps or Direct Electric Heating and DX Cooling.With staged outputs the main AHU Controls 2 stages of Heat and 2 stages of cool

•Further Stages of Heating and Cooling are provided using theAHU Cascade Submodule which adds 3 additional stages of Heating or Cooling giving a maximum of 5 Stages of Heating and 5 Stages of Cooling.

•Each AHU Cascade submodule adds 3 stages of Heating or Cooling depending on the type selectedType /001 for Heating Type /002 for Cooling

•No Configuration Parameters exist in this submodule.The Type of submodule is not user changeable and the appropriate type must be specified at time of order.

•Number of Stages of Heating or Cooling required are set using the HSTG and CSTG Configuration Parameters in the AHU Controller. Range 1-5 Stages

Multi Stage Outputs usingAHU Cascade submodule

Each AHU Cascade submodule adds 3 Stages of Heating or Coolingto a maximum of 5 stages of each

Actuator submodulefor Analogue 0-10 Volt Drive Valves

•Main AHU Controller has switching outputs for Raise Lower Type Valves.

•For Analogue 0-10 Volt Valves use Actuator Controller Registered to the AHU ControllerType ACT/DIN/AOP/921 gives 2x 0-10 Volt Ouputs to control Heating and Cooling Valves

•No Inputs to the Actuator Controller are required in this application


Driving Analogue Valves usingActuator Controller submodule

Actuator Controller gives 2x 0-10 Volt Outputs to drive Heating andCooling Valves

0-10 VoltDrive toValves


DeHumidification Control byadding Intelligent T/Rh Sensor

DeHumidification Controlusing Intelligent Temperature and Humidity T/Rh Sensor

•Main AHU Controller can be used for DeHumidification Control when an Intelligent T/Rh Sensor is fitted

•Sensor Type must be Return Air use Duct Sensor Type SEN/PR/TRH/001 orRoom Sensor Type SEN/PTR/TRH/005

•Supply Air Temperature Sensor must be fitted regardless of AHU type. Intelligent T/Rh Sensor provides Return Air Temperature so no need for a separate Return Temperature Sensor

•To set up DeHum Control:• Register Intelligent T/Rh Sensor to AHU Controller• Set RHSP Parameter in AHU Controller to

Rh Setpoint. Setting this Parameter to a non Zero value enables DeHum Control

Intelligent SensorSEN/PR/TRH/001


•Control Method is On-Off ControlCooling is set to 100% when DeHum required and to Temperature only Control when Rh Setpoint achievedRh Hysteresis Deadband is set on RHDB Parameter in the AHU ControllerHeater Battery reheats the dehumidified air back to the Supply Air Temperature Setpoint when in DeHum ModeThis control method provides suitable control for Human Comfort Conditions but does not control to narrow Deadband needed for Close Control Laboratory Applications. see Humidity Controller section for close control applications

•Any AHU Type can be used for DeHum Control provided T/Rh Sensor fitted. For systems without Extract Fans such as Fresh Air Supply AHU’s use Room Sensor to measure Rh

•Supply and Outside Air T/Rh Sensors can be fitted to the AHU but these are for monitoring purposes only and take no part in the Control in this Mode

•No Configuration Parameters exist in the Intelligent T/Rh Sensors. It is not possible to alter the Sensor Type from Supply to Return Air from the Zone Controller or InSite so the appropriate Type must be specified at Order

DeHumidification Control byadding Intelligent T/Rh Sensor


PreHeater submoduleControl of LPHW or Electric PreHeater Battery

•PreHeater Battery heats incoming air in low ambient conditions to prevent Cooling Battery or Filters from freezing

•Temperature Sensor for PreHeater Off Coil Temperature is normally fitted. PreHeater is enabled if Air Temperature fallsto OCSP Parameter preset 5 DegC and controls the Off Coil Temperature to this value.Without Temperature Sensor the PreHeater Output is Scheduled ON as the Outside Air Temperature falls below the OCSP Parameter. This should be regarded as a safety default if the Off Coil Temperature Sensor fails not as a Primary Control Method

LPHW Battery Control•Raise - Lower Valves use PRE/DIN/3T/105

Analogue Drive Valves use PRE/DIN/AOP/721

•Circulation Pump can use Output Channel C or Analogue Output B

•Heat Demand is sent from Main AHU Controller provided it has Wet Heating Battery specified. The Heat Demand is not set up from the PreHeater submodule

•Set HDLY Parameter to negative value - suggest -5.0 to give 5 minute delay on Preheater during Cold Start Routine

Cold Start RoutineIf the Ambient Temperature is below OCSP Parameter - default5 DegC - then the unit will go through a Cold Start Routine as follows:

1 Heat Demand sent from AHU Controller to Boiler to provide Hot Water

2 When Boiler Temperature rises above Minimum Value then PreHeater Battery Valve will open 100%

3 After the PreHeater Valve has been open for the Delay Time set on the HDLY Parameter then the Fans will runHDLY must be set to a negative value to enable this feature Default Value 0

4 AHU runs in Automatic Control Mode


Electric Heater Battery Control•Staged Electric Heating use:

PRE/DIN/3T/108 for 2 stage OutputPRE/DIN/3T/109 for 3 stage Output

•Solid State Relay Drive use PRE/DIN/3T/421 for Fast Time Proportional Output

•Fan Run On set HDLY Parameter to positive value to enable Fan Run On and to set Run On Time in Minutesfor example set HDLY = +5.0 to set Fan Run On to 5 MinsFans will continue to run for 5 Mins after Electric PreHeater Battery is turned Off to dissipate heat from electric heater elements

PreHeater Control

AHUController

PreHeatersubmodule

Supply


Heat Recovery submoduleControl of Run Round Coils, Face/Bypass Dampers or Heat Wheels

•Measures Return Air and Ambient Air Temperatures and willinitiate and Control Heat Recovery if Energy can be saved.Works in both Heating and Cooling Modes

•Return Air Temperature Sensor must be fitted to main AHU Controller regardless of AHU SPTY Type.Heat Recovery submodule receives Return Air Temperature measurement from main AHU Controller and Outside Air Temperature that is Broadcast by the Housekeeper Module

•ON - OFF Devices such as Run Round Coils with Pump Control do not use a Temperature SensorUse HRC/DIN/3T/001 and connect Pump to Output A the Time Proportional Output

•Modulating Heat Recovery DevicesFit Temperature Sensor to measure air after Heat Recovery Device. Temperature will be Controlled to maximise use of Heat Recovery

Modulating Valves on Heat Recovery Coilsuse HRC/DIN/3T/006Modulating Dampers on Face/Bypass Recuperatorsuse HRC/DIN/3T/006 for Raise Lower Actuatorsor HRC/DIN/AOP/001 for Analogue ActuatorsVariable Speed Thermal Wheeluse HRC/DIN/AOP/001 Output A 0-10 Volt to Drive Speed


Heat Recovery Control

Select Type of Heat Recovery submodule to match Type of Plant

AHUController

PreHeatersubmodule

Supply

Return


Mixing Damper submoduleControl of Mixing Dampers for Heat Recovery,Air Quality Control or Enthalpy Control

Heat Recovery•Measures Return Air and Ambient Air Temperatures and

Modulates Mixing Dampers if Energy can be saved.Works in both Heating and Cooling Modes

•Return Air Temperature Sensor must be fitted to main AHU Controller regardless of AHU SPTY Type.Mixing Damper submodule receives Return Air Temperature measurement from main AHU Controller and Outside Air Temperature that is Broadcast by the Housekeeper Module

•Mixed Air Temperature Sensor is NOT normally fitted.The Mixing Dampers are controlled as the First Stage of the main AHU Heating or Cooling Control Loop if free Heating orCooling is availableSet DMPC Parameter to 20% (Default=0) Mixing dampers will operate over first 20 % of AHU’s OutputSet HRMN C154 and CRMN C155 in main AHU Controller to20% to rescale Driver Outputs to accommodate Mixing Damper Control using InSite or Doorway

•Mixed Air Temperature can be used to Control the Mixing Dampers. Set DMPC Parameter =0 (Default=0)This method of control is not normally used because the Air may not have mixed before it reaches the single point Temperature Measurement used and so the reading is not representative

•Minimum Fresh Air can be set. Use MNFA Parameter to set minimum Damper Open Position during normal Running

•Select Module Type depending on Actuators:Raise Lower Actuators use DAM/DIN/3T/001Analogue 0-10 Volt Actuators use DAM/DIN/AOP/001


Air Quality Control•Fresh Air Rate is increased from the Minimum Fresh Air

level set on Parameter MNFA as Measured Air Quality Reduces

•Air Quality Measurement is made by an appropriate Sensor that provides 0-10 Volt Input to the Mixing Damper submodule.Use Sontay Air Quality Sensor with SeaChange Transformer Module TRN/DIN/5.5/001Can use Carbon Monoxide or Carbon Dioxide Measurement for more specialist Air Quality Control

•Humidity Control for Pool Areas can be simply controlled using this submoduleUse 0-10 Volt Humidity Sensor connected to submoduleMixing Dampers are Opened to decrease Pool Area Humidity assuming that the Ambient Air has a lower Moisture Contentthan the Pool Area

•Set Air Quality Level using MNAQ and MXAQ ParametersMNAQ is Minimum Air Quality level that will open the Damper more than the Minimum Fresh Air PositionThe Damper position is Scheduled so that the Dampers are fully Open if Air Quality reaches MXAQ level The Air Quality Parameter Settings are a percentage of the 0-10 Volt Measured Air Quality Signal.

Heat Recovery Control usingMixing Damper submodule

Select Type of Mixing Damper submodule to match Type of Plant

AHUController

Mixing Dampersubmodule


Enthalpy ControlControl of Mixing Dampers based on Enthalpy

•Measures Return Air and Ambient Air Humidity and Temperature and calculates Enthalpy of both Air Streams Modulates Mixing Dampers to minimise added Enthalpy and maximise Energy EfficiencyWorks in both Heating and Cooling Modes

•Return Air Intelligent T/Rh Sensor must be fitted to main AHU Controller regardless of AHU SPTY Type.Mixing Damper submodule receives Return Air T/Rh measurement from main AHU Controller.

•Ambient Air Intelligent T/Rh Sensor must be fitted, one per AHU

•Minimum Fresh Air can be set. Use MNFA Parameter to set minimum Damper Open Position during normal running

•Select Module Type depending on Actuators:Raise Lower Actuators use DAM/DIN/3T/001Analogue 0-10 Volt Actuators use DAM/DIN/AOP/001

•Monitor Enthalpy Reading using Parameters EOUT and ERTN for Ambient and Return Enthalpy Reading

Enthalpy Control of Mixing Dampers using Mixing Damper submodule and Intelligent T/Rh Sensors

Use Intelligent T/Rh Sensors for Return and Ambient Air Measurementfor Enthalpy Control

AHUController

Mixing Dampersubmodule




Static Pressure submoduleVaries Fan Speed to Control Pressure or Air Quality

•Varies Fan Speed or Inlet Guide Vane to alter Air Volume

•Supply and Extract Fan Outputs each 0-10 Volt are providedExtract Fan Output is Ratio of Supply Fan ValueSet by ELAG parameter +/-50%

• Input Measurement for Pressure in Index Duct or Air Qualityrequires 0-10 Volt input from appropriate Sontay Sensor or similar Use with transformer TRN/DIN/5.5/001 for 24v ac

•Range Input to Engineering Units use MXPV and MNPV to calibrate Engineering units corresponding to 0 and 10 Volt Input. Use DPPV to set decimal Point in Engineering Units

•Pressure Control is commonly used in Variable Air Volume VAV applications to provide fixed Control of Static Pressure as the Air Volume changes

•Air Quality Control is achieved by increasing Fan Speed as Air Quality Reduces. To achieve this Control the output sense is inverted compared to the Pressure Control Application Set INVL Parameter =1

Static Pressure submodule varies Fan Speed to ControlDuct Static Pressure or Air Quality

Connect Pressure or Air Quality Sensors to submoduledepending on Application

AHUController

Static Pressuresubmodule


Humidity submoduleControl of Humidification

•Works with DeHumidification Control section 3 22Must fit Return Air or Space Intelligent T/Rh Sensor and Register it to the AHU Controller AHU passes Rh measurement to Humidity submoduleSet RHSP DeHum Setpoint and RHDB DeHum Hysteresisin AHU Controller

•Humidity Setpoint set on SPRH Knob found in submodule Monitoring Parameters Default 50% RhSet SPDB Humidity Control Deadband =0Set CMDE =1 Control Mode Closed Loop Humidity ControlFor Example set RHSP = 65 RHDB = 10 in AHUand SPRH=40 SPDB=0 CMDE=1 in Humidity submoduleDehum will cycle 60 to 70% Rh: Humidity control to 40% Rh

•Output Types to suit plant0-10 Volt Output use HUM/DIN/AOP/001Staged Outputs Use HUM/DIN/3T/008 for 2 Stagesor use HUM/DIN/3T/009 for 3 Stages

•Close Control of Humidity is possible with this submodule Contact SeaChange for Application advice

Humidity Control using Humidity submodule andIntelligent T/Rh Sensor for Return Air

Humidity control requires Humidity submodule and Intelligent T/Rh

AHUController

HumiditySubmodule



Fan Changeover submoduleControl of Twin Fan Pairs

•One Pair of Fans either Supply or Extract are Controlled by each Fan Changeover submodule

•Supply or Extract Fan Types can be selected at Order or can be selected from the TYPE Parameter

•One or Two Fan Status Signals can be used.Either use one Flow Switch across both Fans or use 2 Contactor Run Status signals, one from either fan.

Control of Twin Fan Pairs by Fan Changeover submodule

Use separate Fan Changeover submodules for Supply and Extract Fans

AHUController

Fan Changeoversubmodule


Extract FansExtract Fans may be linked to the operation of an AHU e.g. for Toilet Extract, or may be controlled independently, and linked to some other function e.g. the occupancy of a particular area in a building. Extract Fans may be single fans operating alone, or Twin Fans operating on a duty/standby basis, or multiple fans that are switched on a staged basis according to a demandsignal.

Single ExtractFan

TwinDuty/StandbyFans with AutoChangeover

Triple StagedExtract Fans

Extract Fans


Control of different Extract Fan arrangements

AHU Extract Fans• Single Extract Fan working with an AHU; if close to the

AHU Controller use its Extract Fan output If remote from AHU Controller, use Actuator Submodule ACT/DIN/3T/101 registered to the AHU Controller using the Occupation Switch output.

•Twin Extract Fan working with an AHU in Duty/Standby mode; use a Fan Changeover Submodule FCO/DIN/AHU/002 registered to the AHU. The AHU will control the twin fans Run Status, and is interlocked with the AHU The fans will change over from duty to standby upon duty fan failure. A fan status signal is required, not a trip signal.

• Staged Extract Fans working with an AHU; use an Actuator Controller registered to the AHU. Use ACT/DIN/3T/108 for more stages based on AHU Heating Demand or /208 for AHU Cooling Demand or /308 for more stages based on AHU Heating or Cooling Demand. The Occupation Switch output is used to switch the continuously-running stage, and the remaining 2 outputs are used to switch the demand-switchedstages.

Single Extract Fan

ACT/DIN/3T/101

Occupation switch output onactuator drives extract fan


Remote Extract Fans driven from Actuator Controller

Non AHU Extract Fans•Single Extract Fan working with a single area; use Actuator

Submodule ACT/DIN/3T/101 registered to the Zone Controller using the Occupation Switch output.

•Twin Extract Fan working with a single area; use ChangeoverSubmodule PCO/DIN/3T/005 registered to the Zone Controller. The fans will duty-rotate every time the Zone enters Occupancy, and will change over from duty to standbyupon duty fan failure. A fan status signal is required, not a trip signal.

• Staged Extract Fans working with a single area; use an Actuator Controller registered to the Zone Controller. If you want one stage to run all the time during occupancy, use a ACT/DIN/3T/108 for more stages based on Zone Heating Demand or /208 for Zone Cooling Demand or /308 for more stages based on Zone Heating or Cooling Demand. The Occupation Switch output is used to switch the continuously-running stage, and the remaining 2 outputs are used to switch the demand-switched stages.

Twin Extract Fan - Single Zone

PCO/DIN/3T/005

Changeover Module drives Twin Extract Fan - will run onZone Occupancy Times


Toilet Extract• some applications need fans to run when any one of a

number of areas of the building are occupied e.g. Toilet Extract Fans, Stairwell Vent Fans

• use Secondary Circuit Controllers to collate Occupancy Demand signals from Zone Controllers; any Zone entering Occupancy will cause the fans to run.

• the collated Occupancy Demand can be passed on to anothermodule e.g. an AHU Controller, if that has to run as well

• Occupancy Demand Parameter OCDS must be manually set on Zone Controllers to send signal to Secondary Circuit ControllerThis connection must be manually set. It does not automatically set by Push Button Registration.

• Single Extract Fan working with multiple Zones; use CTU/DIN/3T/101 using the Occupation Switch output.

• Twin Extract Fan working with multiple Zones; use CTU/DIN/PCO/3T/004. The fans will duty-rotate every time they start, and will change over from duty to standby upon duty fan failure. A fan status signal is required, not a trip signal.

• Staged Extract Fans working with multiple Zones; use CTU/DIN/3T/108 for more stages based on Zone Heating Demands or /208 for Zone Cooling Demands. The Occupation Switch output is used to switch the continuously-running stage, and the remaining 2 outputs are used to switch the demand-switched stages.This Module must be driven by Heat and Cool Demands not Occupancy Demand as the Demand level is used to determine the number of stages that are running


Twin Extract - Multi Zonee.g. Toilet Extract Fan

CTU/DIN/PCO/004

Secondary Circuit Changeover moduleused for Toilet Extract Fans.Driven from Zone occupancy demand,any Zone in occupation will drive fans on.


Toilet Extract Fans controlledby Secondary Circuits withChangeover

3 40 AHU’s

Examples - AHU SystemsExample 1 - Fresh Air Plant

This example represents the smallest SeaChange System:

•Zone Controller - must have one in every system

•AHU Controller - with the System Housekeeping function

•Power Supply - system will not function without one.

Extract

Supply

Example 1 - Fresh Air Plant

AHU’s Examples 3 41

AHUController

AHU General•AHU is a Fresh Air plant providing Tempered Fresh Air i.e.

Outside Air heated or cooled to a constant supply temperature.

•AHU Controller is performing System Housekeepingfunction and therefore needs an Outside Temperature Sensor- could be a conventional sensor hardwired to its input terminals, or use an Intelligent Sensor connected to the network, and registered to the AHU ControllerUse AHU/DIN/FRE/WW/SH/001

• for systems with Boiler plant, you may already have a Boiler Controller with System Housekeeping; you can only have oneHousekeeper per system, so you will need to choose a non-housekeeping AHU Controller. See System Design section 7Use AHU/DIN/FRE/WW/NH/001

Sensors•must fit Supply Air sensor and Outside Air sensor, see above

•can fit Return Air sensor for monitoring, or it may be needed for control - Night Cooling etc. - see AHU section

Inputs• inputs for Fan Status and Filter Status are optional; note

these need to be status from pressure switch or contactor auxiliary, not trip signals

• input for remote disable/enable Volt-Free Contact or external potentiometer for setpoint trim are optional; see Data Sheet.

Outputs• this example has wet heating and cooling batteries; other

types i.e electric or direct gas-fired, will mean you need to choose a different output option - see AHU section

Valves• this example uses Raise / Lower type valves; if 0-10V dc

valves are used, you need an additional Actuator Submodule registered to the AHU Controller to give 0-10V dc outputs for heating and cooling. Note that 0-10V dc valves give no control benefits over Raise/Lower valves.

3 42 AHU’s Examples

Occupancy Demand• the AHU will be made to run depending on the Occupancy

Status of one or more Zone Controllers - you must have at least one Zone Controller registered to the AHU with an Occupancy Demand Interconnect to make it run. The Zone Controllers will each send an Occupancy Demand signal to the AHU Controller; the AHU will run when any Zone is in Occupancy.

• the Zone Controllers could be doing another job as well e.g. controlling a radiator circuit.

• the AHU Controller can send its Energy Demand signals to other modules controlling the CT Circuits feeding Hot or Chilled Water to its batteries if it has “wet” batteries. These signals are sent using Energy demand Interconnects.


Equipment List

1 AHU/DIN/FRE/WW/SH/001 AHU Controller for Constant Supply Air control with System Housekeeping*

1 ZON/PTR/LCD/001 Zone Controller - user interface to set operating times etc.**

1 PSU/DIN/500S/230V/TER System Power Supply - note; number and type of PSUs needs to be considered for the system as a whole - see System Design section 7

2 SEN/PR/DCT/001 Duct Sensor for Supply and Extract Air1 SEN/PR/OAT/001 Outside Sensor

* if Boiler Controller present, use /NH variant without Housekeeping** may be more than 1 Zone Controller; also may use Zones for more than 1

task

Interconnect Diagram•Occupancy Demand signals are generated by Zone

Controllers - there may be more than one for multi-zone buildings fed from the same AHU.

•when any of the Zones enters Occupancy, the AHU will run. When all of the Zones are in non-Occupancy, the AHU will stop after any run-on time has elapsed.

•Energy Demand signals for Heating and Cooling may be sent to other modules e.g. Secondary Circuit Controllers.

Example 1 - Fresh Air Plant

Cooling Demandsignal to Chiller plant

Occupancy Demandsignals from other Zone orSlave Zone controllers

Heating Demandsignal to Boiler plant


Zone Controllers drive AHU on using OccupancyDemand Interconnect

Configuration Parameter SettingsAutomatically set during Registration

•OCDS parameter in the Zone Controllers will automatically be set to 51 because the AHU is address A1; if it was A2, OCDS would be set to 52, and so on.

•HTSC and CLSC Parameters in the AHU Controller would beautomatically set to “point” the AHU’s Heating and Cooling Demand signal at the modules which are controlling the flowof water to the Heating and Cooling Coils, not shown.

Parameters that must be set manually

•no other parameters have to be adjusted

Examples of Parameters that may need to be set manually

•if fan or filter status are wired to the AHU Controller inputs, the ALRM and ALST Parameters may need to be adjusted - see Data Sheet.

• if you wish to use Setpoint Supervision to allow the user to adjust the Supply Air temperature from a Zone Controller, setSPTY to 4, and then register to the Zone for Setpoint Supervision Interconnect, it does not have to be one of the Zones that is being used for Occupancy Demand control

• if using an external enable/disable signal, adjust INMD accordingly - see Data Sheet.

• if you are using the Night Cooling feature to pre-cool the building, set NTCL to the desired setpoint.

•RHSP is the setpoint for de-humidification control; if the AHU is capable of de-hum, this can be set to a non-zero value which will enable de-hum and be used as the setpoint.



Example 2 - Return Air ControlThis example shows the addition of Submodules to an AHU Controller to control a more complex AHU.

AHU General•AHU is a Return Air plant providing Conditioned Air i.e.

Outside Air heated or cooled, humidified or dehumidified to a variable Supply Air setpoint so as to achieve constant return air temperature and humidity.

•AHU Controller is performing System Housekeeping*function and therefore needs an Outside Temperature Sensor which could be a conventional sensor hardwired to its input terminals, or use an Intelligent Sensor connected to the network, and registered to the AHU Controller

• for systems with Boiler plant, you may already have a Boiler Controller with System Housekeeping; you can only have oneHousekeeper per system, so you will need to choose a non-housekeeping AHU Controller. See System Design section 7for details

Extract

Supply

Example 2 - Return Air Control


Sensors•must fit Supply Air temperature sensor and Outside sensor

•must fit Return Air temperature + humidity sensor to allow humidity control; this is an Intelligent Sensor, and is wired to the network rather than direct to the AHU Controller, and registered to the AHU Controller as a Submodule

Inputs•see example 1 for details


types i.e electric or direct gas-fired, will mean you need to choose a different output drive option - see AHU section

Valves• the Cooling and Reheat batteries use Raise / Lower type

valves; if 0-10V DC valves are used, you need an additional Actuator Submodule registered to the AHU Controller to give0-10V DC outputs for heating and cooling. Note that 0-10V DC valves give no control benefits over Raise/Lower valves.

• the Preheat battery also uses a Raise/Lower valve; another variant of Preheater Submodule is available to control 0-10V DC valves.

Dampers• the Mixing Dampers are controlled by a Damper Submodule.

This has 0-10V DC outputs for repeatable positioning of the dampers for minimum fresh air position.

Humidifier• the Humidifier is controlled by a Humidity Submodule.

0-10V DC or Staged outputs are available to suit the Humidifier

Demand Signals•you must have at least one Zone Controller registered to the

AHU with an Occupancy Demand Interconnect to make it run. See example 1.

• the AHU can send Energy Demand signals to other modules; see example 1.


Equipment List

1 AHU/DIN/RET/WW/SH/001 AHU Controller for Constant Return Air control with System Housekeeping*

1 ZON/PTR/LCD/001 Zone Controller - user interface to set operating times etc.

1 PRE/DIN/3T/105 Preheater Submodule1 DAM/DIN/AOP/001 Damper Submodule1 HUM/DIN/AOP/001 Humidity Submodule1 PSU/DIN/500S/230V/TER System Power Supply - note; number and

type of PSUs needs to be considered for the system as a whole - see System Design section

1 SEN/PR/DCT/001 Duct Sensor for Supply Air1 SEN/PR/OAT/001 Outside Sensor1 SEN/PR/TRH/001 Intelligent T+Rh sensor for Return Air* if Boiler Controller present, use /NH variant without Housekeeping



Controllers - there may be more than one for multi-zone buildings fed from the same AHU.

•when any of the Zones enters Occupancy, the AHU will run. When all of the Zones are in non-Occupancy, the AHU will stop after any run-on time has elapsed.

•Energy Demand signals for Heating and Cooling may be sent to other modules e.g. Secondary Circuit Controllers or direct to Chiller or Boiler Controllers

•Submodules are registered to the AHU Controller; this sets up the special AHU Submodule Interconnects so that the AHU Controller and its Submodules can act together as one large virtual module, with all necessary interlocks etc.

•be careful when designing a system with many Submodules; each AHU Controller has a limited registration capacity for registering Submodules - see System Design section

Example 2 - Return Air ControlHeatingDemand signalto Boiler plant

CoolingDemand signalto Chiller plant

Return Air T + Rhintelligent sensor

Mixing Dampers Preheat Valve Humidifier



•OCDS parameter in the Zone Controllers are automatically set to 51 because the AHU is address A1; if it was A2, OCDS would be set to 52, and so on.

•HTSC and CLSC Parameters in the AHU Controller are automatically set to “point” the AHU’s Heating and Cooling Demand signal at the modules which are controlling the flowof water to the Heating and Cooling Coils, not shown.


•to enable de-humidification control, set RHSP in the AHU Controller to the desired Return Air RH dehum setpoint, the default value of zero disables dehum.

•the parameter SPRH in the Humidity Controller sets the humidification setpoint; it is important to leave a deadband between the Humidification and Dehumidification setpoints, so set it perhaps 5% or 10% lower than RHSP.

• the above two steps will set up normal humidification control; other forms of control are possible, see Humidity submodule Data Sheet

• the minimum fresh air position for the dampers needs to be set; once this is established by measurement of airflow during commissioning, the position of the dampers may be read on HDMD, and this value is then entered into parameterMNFA to set the minimum fresh air position.


•see example 1 for some common settings

• if no off-coil sensor is being used for the preheater, it may be necessary to adjust DEGR parameter - see Data Sheet



Example 3 - Large Building AHU’sThis example works in conjunction with examples in other sections to describe a complete application for a large Commercial Building. This part of the example describes the Air Handling plant in the building. It has 2 plants; one provides tempered fresh air to the office areas, the other ventilates the toilets.

feedingMain OfficeArea

feedingToilets

Large Building - Example 3


Fresh Air AHU’s with remote Extract Fans

AHU General•AHUs are both Fresh Air plants providing Tempered Fresh

Air i.e. Outside Air heated or cooled to a constant supply temperature.

• the System Housekeeping function is being performed by theBoiler Controller - see Heating Section so the AHUs are both non-Housekeeping variants

Sensors•must fit Supply Air sensors to both plants

•can fit Return Air sensor for monitoring, or it may be needed for control - Night Cooling etc. - see AHU section

Fans• the Supply Fans of both plants are switched by the AHU

Controllers

• the Office Extract Fan is mounted remote from the AHU, an Actuator Submodule, registered to the AHU Controller is used to switch the extract fan, use Occupation Switchoutput.

• the Toilet plant has twin extract fans with auto changeover a Fan Changeover Submodule, registered to the AHU Controller is used to switch both fans. A status signal from the fans is required, not a trip signal.

Inputs•see previous example for details


types i.e electric or direct gas-fired, will mean you need to choose a different output driver option - see AHU section

Valves• the Cooling and Reheat batteries use Raise / Lower type

valves; if 0-10V DC valves are used, you need an additional Actuator Submodule registered to the AHU Controller to give0-10V DC outputs for heating and cooling. Note that 0-10V DC valves give no control benefits over Raise/Lower valves.


Demand Signals•at least one Zone Controller must be registered to the Office

AHU with an Occupancy Demand Interconnect to make it run. Here, the Zone Controllers Supervising the occupancy ofthe Fan Coils in the space are all “pointing” their Occupancy Demand signals at the Office AHU - see Fan Coil section.

• the AHU can send Energy Demand signals to other modules; here, the Office and Toilet AHUs will both send their heatingdemands to the Secondary Circuit Controller controlling the AHU CT Heating pumps - see Heating Section.

• the Office AHU sends its Cooling Demand signal to the Secondary Circuit Controller controlling the AHU Chilled Water pumps - see Cooling Section.

Equipment List

2 AHU/DIN/FRE/WW/NH/001 AHU Controller for Constant Supply Air control with no System Housekeeping*

Zone Controllers see Fan Coil Section**1 FCO/DIN/3T/AHU/002 Fan Changeover Module to control twin toilet

extract fans, duty rotation and autochangeover

1 ACT/DIN/3T/101 Actuator Controller to control office extract fan

1 PSU/DIN/500S/230V/TER System Power Supply - note; number and type of PSUs needs to be considered for the system as a whole - see System Design section

2 SEN/PR/DCT/001 Duct Sensor for Supply Air temperatures

* Housekeeping performed by Boiler Controller - see Heating Section** at least one Zone Controller is necessary to make plant run.



Controllers, not shown here, see Fan Coil section, and “point”at the Office AHU

•when any of the Zones enters Occupancy, the AHU will run. When all of the Zones are in non-Occupancy, the AHU will stop - after any run-on time has elapsed.

• the Office AHU passes on the Occupancy Demand Signal to the Toilet Vent Plant, so that if the Office AHU is running, the Toilet Vent Plant will run as well.

OccupancyDemand signalsfrom Office ZoneControllers - seeFan Coil section

Heating Demandsignals to MainHeating plant -see Heatingsection

Cooling Demandsignals to MainChiller plant - seeCooling section

Office Extract Fan

Toilet Extract Fans

Office AHU

Toilet AHU

Large Building - Example 3


•Energy Demand signals for Heating and Cooling are sent to the Secondary Circuit Controllers

•Fan Changeover Submodule is registered to the Toilet AHU Controller; this sets up the special AHU Submodule Interconnect so that the AHU Controller and the Changeover Submodule can act together as one large virtual module; if the Extract Fans fail, the AHU will be shut down.

•Actuator Submodule is registered to the Office AHU Controller; this sets up the Control Demand Interconnect, which contains the Occupancy information to drive the extract fan


•OCDS parameter in the Zone Controllers are automatically set to 51 because the Office AHU is address A1.

•HTSC and CLSC Parameters in the Office AHU Controller are automatically set to 2 and 3 respectively to “point” the AHU’s Heating and Cooling Demand signal at the modules which are controlling the flow of water to the Heating and Cooling Coils, which are at addresses H2 and C3respectively - see Heating and Cooling sections

•HTSC Parameter in the Toilet Vent AHU Controller will be automatically set to 2 - it does not have a Cooling Battery so its CLSC parameter will be 0


•OCDS parameter in the Office AHU Controller must be set to52 to “point” the Occupancy Demand signal at the Toilet Ventplant. Occupancy Demand Interconnects between AHUs cannot be set by registration, they must be manually adjusted.


•see previous examples for some common settings


AHU

Documents

air handling

twin fan pairs

zone buildings

conventional

10v dc outputs

energy demand

fresh air

cold start