HWS Heater (alternative) Electric Heater Stage 2 IQLVAV Electric Heater Stage 1. , P Serial Fan on/off SUPPLY AIR. Parallel Fan

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1 Data Sheet Variable Air Volume Strategy HWS Heater (alternative) Electric Heater Stage 2 IQLVAV Electric Heater Stage 1, P Serial Fan on/off Variable Fan damper Lon 2, 3, 4-port modulating valve Variable Air Volume Strategy SUPPLY AIR Parallel Fan Supply air thermistor temperature sensor T SP Local SP adjust T Local space thermistor temperature sensor EXTRACT AIR Pb Input Description The variable air volume strategy () controls a proportional damper, an on/off fan (either serial or parallel), and two stages of electric heating or a hot water battery, in response to a thermistor temperature sensor and an integral differential pressure sensor with a local setpoint knob, a local pushbutton input, and an alarm contact. The supply air temperature is monitored. Features VAV control according to cooling demand Integral damper actuator Integral differential pressure sensor On/off fan control Two stages of electric heat or a hot water battery Conforms to LonMark profile 8502 Connections outputs = L A common - A? JHE? 0 A = J 5 JO A - A? JHE? 0 A = J 5 JO A Lower Raise, # #, " "! " ",!! #, $ " Damper shaft DO6 - raise DO7 - lower. = %, inputs JK I " 8 8 ) & & Alarm Contact Pushbutton # 4, 1 # $ 1 " # " DUCT Local Setpoint Adjust Potentiometer Supply Air Temperature Sensor Local Space Temperature Sensor % + & 1 ' 1! + 1! Lo Hi P Differential Pressure Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 1

2 Data Sheet Connections (continued) Room Display RD-IQL, room display connects via one input (IN5) and has options. RD-IQL/K: includes space temperature sensor with setpoint adjustment. It precludes the use of occupation override pushbutton (IN4). RD-IQL/KOS: as for RD-IQL/K plus occupation override pushbutton and status display. RD-IQL IQLVAV " 8 # 4, 1 # # IQ System Sensors Inputs can be provided by IQ system sensors TB/TS space temperature sensor: /K.plus potentiometer, /KE..plus pushbutton - # " IQLVAV! " # 8 8 $ 1 " % ) & 4, 1 # + # " & polarity independent! & 1 Note that the IQLVAV must be configured using text communications to use the RD-IQL. The settings are listed in the Using RD-IQL section p15. IQLTool2 facilitates these changes. 6 * 6 5 ' 1! +! 1 FUNCTIONALITY The IQLVAV functionality is described in the IQLVAV data sheet TA This data sheet describes the additional functionality present when the controller is running a /VAV standard strategy. Inputs The following real sensors and digital inputs are connected to the input channels and their values can be monitored by text comms (including IC Comms): Real Sensors S9 (IN1): Local Space Temp, the thermistor temperature sensor reading. S10 (IN2): Local SP Adjust, the local setpoint adjustment potentiometer value scaled in the range 0 to 1, and added to the default S10 offset of -½ to produce the range -½ to +½. This generates a setpoint trim in the range -1 C to + 1 C when the default Offset Range (K15) of 2 C is used. S11 (IN3): Supply Air Temp, the temperature of the supply air is monitored. This sensor is optional as it takes no part in the main strategy. S14 (IN6): Air DPressure, the differential pressure sensor reading from the integral sensor is scaled 0 to 500 Pa by default. Real Digital Inputs I12 (IN4): Push Button, this pushbutton input must close for a least 1 second when the occupation override is required. When the contact closes, it switches the state from any occupation state into the Bypass state for Pb PIR Run On time (G1(F), default 30 mins). The Bypass state also produces Unit Occupied state. I13 (IN5): Alarm Contact; this input is an alarm contact (e.g. filter blocked). Outputs Channel 1, (DO1 terminal 6): This triac output is used to switch the supply fan on or off. If the relay is energised the fan is on. The fan is normally on for heating, and a serial fan (set by Serial Fan Ena(ble), W2) is also on for cooling during non-occupation, and constantly during occupation. The fan is left on if the electric heater is cooling down. Channel 2, (DO2, terminal 5): This triac output is used to switch the Electric Heat Stage 1 on or off. If the relay is energised the Electric Heat Stage 1 is on. As the heating demand rises above 15% the electric heat stage 1 is switched on (as long as Elec Disable, W3, is not set), and switched off as it falls below 5%. Item IN Node Sensors Intern. S1 A1 S2 A2 S3 A3 S4 A4 S5 A5 S7 A7 S8 A8 Real S9 IN1 A9 Knobs S10 IN2 A10 S11 IN3 A11 S14 IN6 A14 K1 A17 K2 A18 K3 A19 K4 A20 K5 A21 K6 A22 K8 A24 K11 A29 K12 A28 K13 A25 K14 A26 K15 A31 K16 A32 Description Space Temp Setpoint Units Occupancy - 0 Default Strategy Items Meaning Default range Bottom Top nv name 20 nvospacetemp 20 nvoeffectsetpt 0(Occupied), 1(Unocc), 2(Bypass), 3(Standby) nvoeffectoccup H eating Demand % nvoheatprimary C ooling Demand % nvocoolprimary Active Air Flow SP Actual Air flow Local SpaceTemp Local SP Adjust Supply Air Temp Air DPressure Remote Setpoint RemoteSpaceTemp OCC Deadbnd Standby Deadbnd NOCC Deadbnd lps lps Knob Pa Remote Occ - 0 Remote SPOffset Htng AirFlow SP thermistor -½ to +½ (potentiometer) nvoairflow nvisetpoint nvispacetemp nvia nvia nvia21 0(Occupied), 1(Unocc), 2(Bypass), 3(Standby) 0 3 nvioccmancmd nvisetptoffset lps k constant Min Airflow SP Max Airflow SP Offset Range lps lps D amper Position % Switches W1 B18, 0 Boost Mode 0 I=Boost Mode nvib18_ 0 W2 B18, 1 Serial Fan Ena 0 I=Fan on constamt during occupation nvib18_1 W3 B18, 2 Elec Disable 0 I=Disable Electric Ht, enable HWS nvib18_2 W8 B18, 7 Remote Shutdown 0 I=Shutdown W16 B19, 7 Damper Override 0 I=Override Digital Inputs Intern. I1 B1, 0 I2 B1, 1 I3 B1, 2 I5 B1, 4 Real I12 IN4 B2, 0 I13 IN5 B2, 1 Fan Enabled U nit Occupied ) Unit Unoccupied 0 ) nvofanspeed 1 (Occ ( default from K6) nvob1_ 1 ( default from K6 nvob1_ 2 Unit in Standby 0 ( default from K6) nvob1_ 4 P ush Button (contact closes =1) A larm (contact open =0) 2 Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04

3 Data Sheet FUNCTIONALITY (continued) Channel 3, (DO3 terminal 4): This triac output is used to switch the Electric Heat Stage 2 on or off. If the relay is energised the Electric Heat Stage 2 is on. As the heating demand rises above 55% the electric heat stage 2 is switched on (as long as Elec Disable, W3, is not set), and switched off as it falls below 45%. Channels 4, 5 (DO4, 5 terminals 3, 2, 1): These two triac outputs are used to control the HWS valve using a raise/lower configuration. The HWS battery is used if the electric heaters are disabled by Elec Disable (W3=I). Channel 6, 7 (DO6, 7 actuator mechanical output): The integral actuator is used to drive the supply damper. The damper is opened according to the cooling demand. It is disabled if there is no cooling during non-occupation Internals The following internal sensors and digital inputs are generated by the strategy and their values can be monitored by text comms (including IC Comms) and LonWorks comms (using network variables). Some can be monitored using display and directory modules (e.g. via NDP). Internal Sensors S1: The Space Temp(erature) used by the strategy. It is normally taken from S9 (IN1), but if there is a sensor fault (read or outside limits) it will use RemoteSpaceTemp (K2). It will also use RemoteSpaceTemp if RemoteSpaceTemp is bound to a Lon sensor. S2: The Setpoint used by the strategy. It is the setpoint set by Remote Setpoint (K1) plus the trim generated by multiplying Local SP Adjust (IN2) by the Offset Range (K15). S3: The Occupancy state of the IQL in the range 0(Occupied), 1(Unoccupied), 2(Bypass), 3(Standby). These states are defined below under Remote Occ (K6). The Remote Occ specifies the occupancy state. The Push Button or Boost Mode (W1) can override from any state into Bypass, but Bypass produces the Occupied state within the unit. The Remote Shutdown (W8) will override into Unoccupied. S4: The Heating Demand is the calculated requirement for heating (0 to 100%) and sets the electric heat requirement. S5: The Cooling Demand is the calculated requirement for cooling (0 to 100%) and sets the air volume during cooling. S7: The Active Air Flow SP is normally the Htng Airflow SP (K9), but if the Htng Airflow SP is disabled, S7 is calculated by choosing a point between Min Airflow SP (K13), and Max Airflow SP (K14) as dictated by the percentage Cooling Demand (S5) S8: The Actual Air flow is normally the air flow calculated from the Differential Pressure sensor. Internal Digital Inputs I1: Fan Enabled, indicates that the Fan is Running. I2: Unit Occupied, indicates that the Unit is Occupied (out of box default). It will be true if the Unit is in Bypass or Occupied as dictated by the Remote Occ (K6), and by the Push Button, or Boost Mode (W1). It is switched off into Unoccupied by Remote Shutdown (W8). I3: Unit Unoccupied indicates that the Unit is Unoccupied as dictated by the Remote Occ (K6). The Push Button or Boost Mode (W1) can switch the unit from unoccupied to bypass state (equivalent to Unit Occupied), but the Remote Shutdown (W8) will override to unoccupied. I5: Unit in Standby indicates the Unit is in Standby as dictated by the Remote Occ (K6). The Push Button or Boost Mode (W1) will override this state to Bypass. It is switched off into Unoccupied by Remote Shutdown (W8). Adjustments The following switch and knob adjustments can be monitored and changed by text comms (including IC Comms), and by LonWorks comms (using network variables). Switches W1: This switch, Boost Mode, forces the unit into Bypass unless overridden by Remote Shutdown (W8). It also sets maximum cooling (zero heating). If W1=O (default) Boost mode is disabled. W2: This switch, Serial Fan Ena(ble), enables the fan constantly during the occupied state and if there is cooling during nonoccupation (in addition to whenever there is a heating demand). W3: This switch, Elec Disable, disables the electric heater if set true (W3=I), and enables the HWS battery. If W3=O (default) the electric heater is enabled and HWS battery disabled. W8: This switch, Remote Shutdown, forces the unit into the Unoccupied state, disables heating and cooling, and switches off the fan (which will close the damper) if set true (W8=1). If W8=O (default) the Remote Shutdown is turned off. W16: This switch, Damper Override, forces the damper to follow the Damper Position, K16, setting. This can be used to set the damper to any position manually for commissioning purposes. Knobs K1: This knob, Remote Setpoint (default = 20 C), is combined with the Local SP Adjust (IN2) to produce the Setpoint (S2). K2: This knob, RemoteSpace Temp (default = 20 C), is used instead of the Local Space Temp (S9) when S9 has an Outside Limits or Read alarm, or if the RemoteSpace Temp is bound to a LonMark sensor (i.e. connected by Lon communications to an output from another Lon device). K3: This knob, OCC Deadbnd (default = 1 C), defines the difference between heating and cooling setpoints during occupation. K4: This knob, Standby Deadbnd (default = 2 C), defines the difference between heating and cooling setpoints during standby. K5: This knob, NOCC Deadbnd (default = 12 C), defines the difference between heating and cooling setpoints during nonoccupation. K6: This knob, Remote Occ, (default =0, Occupied) defines the unit s occupancy state: 0(Occupied), 1(Unoccupied), 2(Bypass), 3(Standby). It can be overridden into Bypass (equivalent to Occupied within the unit) from any occupation state by the Push Button or Boost Mode (W1). The state is overridden to Unoccupied by the Remote Shutdown (W8). Heating and cooling are constantly enabled, coming on as defined by the setpoints, the deadband between the setpoints being widened for the non-occupied states Occupied: A serial fan is on constantly, but a parallel fan is only on if heating is required. The Occupation Deadband (default 1 C) is used. Unoccupied: The Non-occupied Deadband (default 12 C) is used. Both serial and parallel fans come on for heating, but a serial fan will also come on for cooling. Bypass: This effectively produces the same state as occupied but it is intended to be used for a short time only. If the bypass state is produced (either by Remote Occ (K6), Boost Mode (W1), or by Push Button) it will produce the occupied state inside the unit, although Occupancy (S3) will show the bypass state. Standby: This state is designed to reduce energy consumption in the zone (Standby Deadband defaults to 2 C). The unit is put back into occupation by the Push Button or Boost Mode (via Bypass). K8: This knob, Remote SPOffset (default = 0 C), is used instead of the Local SP Adjust (S10) x Offset Range (K15) when S10 has an Outside Limits or Read alarm, or if the Remote SPOffset is bound to a LonMark sensor (i.e. connected by Lon communications to an output from another Lon device). Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 3

4 Data Sheet FUNCTIONALITY (continued) Knobs (non LonWorks comms.) These knobs can only be adjusted by text comms (including IC Comms), not LonWorks comms: K11: This knob, Htng AirFlow SP (default= 50 lps), sets the airflow used when heating. If no heating airflow is specified it should be set the same as K13. K12: This knob, k constant (default = 1) is the box constant used to convert the square root of the pressure into a volume flow rate. The value is either supplied by the VAV box manufacturer or can be found empirically and must be configured into the controller. K13: This knob, Min Airflow SP (default = 50 lps) defines the minimum airflow permitted by the VAV damper. K14: This knob, Max Airflow SP (default = 300 lps) defines the maximum airflow permitted by the VAV Damper. K15: This knob, Offset Range (default = 2 C), is used to define the range of the Local Setpoint Adjust (IN2). The Local Setpoint Adjust is scaled to give a value in the range -½ to +½. This is multiplied by the Offset Range setting to give the setpoint trim which is applied to Remote Setpoint (K1) to produce the Setpoint (S2). K16: This knob, Damper Position (default = 10 %), can be used to manually set the damper position if the Damper Override, W16, is set. It can be used for commissioning purposes. Water Balancing The HWS valve raise/lower output is set to 100% by sending the text comms message R(#=0). The output will remain at 100% (even if the power is switched off and on) until the IQL receives a Text comms message R(#=1). This enables the heating valve to be fully opened for balancing and flushing the water side system. Note that the water balancing command will also fully open the damper. Display and Directory modules There are no display and directory modules. Plot The single plot channel is set to plot the Space Temp sensor S1 at 15 min. intervals (80 readings). It can be changed by text comms - see above. Parameters The following parameter may required to be changed: D5(D): The VAV Damper driver full scale drive time (default = 110 s) may need to be changed if the positions of two motor stops on the actuator drive have been changed. The time should be measured in seconds from fully closed to fully open and the parameter changed if necessary using text communications i.e. D5(D=x). Text Comms The item values can be monitored or changed using text comms as described in the IQ System LonWorks Products Engineering Manual (TE200292). The value of a sensor or knob is referred to by V, and the status of an input or switch is referred to by S. e.g. S1(V) gets value of S1, W1(S=I) sets switch 1 on. Some of the other parameters are: Sensor, Knob, switch, Driver, Input, labels ($) Sensor, Knob: units (%) Knob: (T)op of range, (B)ottom of range Sensor: (O)ffset Driver: (P)eriod, fullscale (D)rive time, t(y)pe Plot: (S)ensor number, (P)eriod (P=0: 1h, 1:15m, 2:24h, 3:1m, 4:5m, 6:20m, 7:30m, 8:6h) Display ~: (I)tem Loop: (I)ntegral, (G)ain, and (R)eschedule times - Note that these loop parameters should not be changed for loop 3 or the strategy performance may deteriorate. LoGic: o(f)f time IC Comms N: remote device (A)ddress, attri(b)ute, remote la(n), (I)nterval, (S)ignificant change, source ite(m), d(e)stination module no., destination i(t)em 4 Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04

5 Data Sheet STRATEGY BRIEF DESCRIPTION The strategy controls a VAV unit (with a proportional damper, electric or HWS heaters, and an on/off fan) in response to thermistor temperature and differential pressure sensor readings. A local setpoint adjustment can trim the setpoint. A pushbutton input can change the occupation state. The controller maintains the temperature of a space to the defined setpoint. The plant diagram on the first page illustrates a typical controller application for the VAV standard strategy. The fan can be either in a parallel or serial configuration; the parallel fan sucks in the extract (hot) air whereas the serial fan sucks in both supply (cool) air and extract (hot) air. The temperature of the air space is achieved by modulating the heater outputs based on the current space requirements and by modulating the supply damper in accordance with the cooling requirement. The supply damper control is achieved by generating an air flow rate setpoint (from either the cooling requirement or the Heating AirFlow SP) and comparing it to the duct Actual Air flow. The damper is closed during non-occupation if there is no cooling demand. The actual air flow is normally calculated from the differential pressure sensor reading. To do this the k constant must be set up. The controller operates in either Occupied, Unoccupied, Bypass, or Standby modes as determined by the Remote OCC setting. The controller maintains the comfort level to a user-defined setpoint. Heating is initially provided by the internal heat gain, but an increase in heat demand is satisfied either by two stages of electric heaters, or by a HWS battery as specified by the Elec Disable setting. If the Elec Disable is set to O, as the heating demand rises to 15 %, the Elec Stage 1 (channel 2) output is first switched on and as it further increases to 55%, the Elec Stage 2 (channel 3) is switched on. As the demand falls to 45% Elec Stage 2 is switched off, and as it further falls to 5% Elec Stage 1 is switched off. If Elec Disable is set to I, the heat demand is connected directly to the HWS valve. The space temperature sensor, local setpoint adjust, and pushbutton inputs can be provided by Trend TB/TS/KE sensor, or by the RD-IQL/KOS room display. The Local SP Adjust, Local Space Temp, Supply Air Temp, and Air DPressure inputs generate both Read and Outside Limits alarms. The read alarm indicates a problem with the controller, and the Outside Limits alarm indicates that the input signal is outside its expected range. An alarm message will be sent both when an alarm condition is detected and when it is cleared if the alarm is enabled by text comms. The Pushbutton, and Alarm contact inputs can be enabled by text comms to generate alarms either on input contact closures or on openings. The controller switches the air fan on or off. Both types of fan will be running for a heating demand. If Serial Fan En is set true, the fan also runs continuously during occupation and for a cooling demand during non-occupation. The occupancy override pushbutton will effectively switch the unit into occupation. Boost Mode overrides the unit into occupation and sets maximum cooling (zero heating) which will fully open the damper. The Remote Shutdown setting will override the unit into the unoccupied state, disable the heating and cooling, and switch off the fan which will close the damper. (However, note that the fan can keep running if the electric heater is cooling down). When cooling, the cooling output is calculated by a proportional + integral control loop based on the space temperature and the cooling setpoint. As the temperature rises above the cooling setpoint the cooling output will be increased. The cooling output will be decreased as the temperature falls below the cooling setpoint. When unoccupied, the cooling setpoint will be increased. When heating, the heating output is calculated by a proportional + integral control loop based on the space temperature and the heating setpoint. As the temperature falls below the heating setpoint the heating output will be increased. The heating output will be decreased as the temperature rises above the heating setpoint. When unoccupied, the heating setpoint will be decreased. The actual cool and heat setpoints are set above and below the user-defined setpoint by half the current deadband. The deadband is increased during non-occupation by having different deadbands for the operating modes, i.e. OCC Deadbnd (used for Occupied and Bypass modes), Standby Deadbnd, and NOCC Deadbnd. Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 5

6 6 Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 Data Sheet Diagram 1: Occupancy State (strategy page 3)

7 Data Sheet STRATEGY (continued) DETAILED DESCRIPTION This section describes the strategy in detail. Note that the strategy diagrams have been produced with SET using standard IQ controller nodes. Other than the nodes associated with knobs, switches, sensors, and digital inputs, the remaining nodes are not implemented in the IQL so should be ignored; also note that knobs 1 to 16 are associated with nodes A17 to A32 which is different to normal IQs. Occupancy State (Diagram 1, strategy page 3) Summary: The controller operating mode is set by Remote Occ (K6) to Occupied, Unoccupied, Bypass, or Standby. The operating mode can be monitored by the Occupancy sensor (S3) or from the Unit Occupied (I2), Unit Unoccupied (I3), and Unit in Standby (I5) internal digital states. The Push Button (I9) forces the unit into Bypass from any state for the Pb Run On time (defined by G1(F), default 1800 s = 30 mins). Boost Mode (W1) also forces the unit into Bypass from any state. Within the unit, the Bypass condition is treated the same as Occupied. The Remote Shutdown (W8) will override the unit into Unoccupied. Detail : The Remote Occ state knob, K6, is set to either 0(Occupied), 1(Unoccupied), 2(Bypass), or 3(Standby) and is normally connected via F3 and F4 to the A to D module F5 whose input is monitored by the Occupancy Sensor S3. The 2 digital bits output by F5 are further decoded by logic modules G5, G7, and G8 respectively to produce the outputs, Unit Occupied (I2), Unit Unoccupied (I3) and Unit in Standby (I5). Note that although S3 will monitor the separate Bypass (S3=2) state, G5 combines Bypass with the Occupied state so that within the rest of the strategy these two states are treated the same. The Push Button input (I9) initiates a pulse at the output of G1 for a minimum time defined by G1(F), the off delay, (default 1800 s = 30 mins). G2 passes the pulse through to F3 which overrides the occupation state to value of constant input F which is set to 2 (Bypass). If the Boost Mode Switch is set, the output of G2 will be held at one and hence the output of F3 will held in Bypass mode. Thus the Push Button or Boost Mode will override the occupation state to Bypass (equivalent to Occupied in the strategy). Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 7

8 8 Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 Diagram 2: Setpoint and Details (strategy page 4) Data Sheet

9 Data Sheet STRATEGY (continued) Setpoint and Details (Diagram 2, strategy page 4) Summary: Setpoints The Local SP Adjust is scaled within the unit to produce a value in the range -½ to +½. This is multiplied by the Offset Range (default = 2 C) to produce a trim (default -1 C to +1 C). This trim is added to the Remote Setpoint (default 20 C) to produce the Setpoint. Setpoint = Local Setpoint Adjust x Offset Range + Remote Setpoint If the Remote SPOffset is bound to a Lon device, then the Remote SP Offset is added to the Remote Setpoint to produce the Setpoint. The Remote SP Offset is also used if Local SP Adjust has a Read or Out of Limits alarm condition. Setpoint = Remote SetpointOffset + Remote Setpoint Space Temperature The Space Temp is normally the Local Space Temp, but if the RemoteSpace Temp is bound to a Lon device, it is used instead. The RemoteSpace Temp is also used if the Local Space Temp has a Read or Out of Limits alarm condition. Detail: The real sensor S10 monitors the Local SP Adjust potentiometer (0 to 1) and adds offset (default -½) to produce S10 output (-½ to +½). Function module F6 normally connects the adjustment to F8 where it is multiplied by the Offset Range K15 (default 2 C) and added to the Remote Setpoint K1 (default 20 C). This produces the actual setpoint monitored by Setpoint sensor S2. If the Remote SPOffset K8 is bound to a Lon device, then Lon Remote Setpoint Offset bit 64.7 is set true. If either this is true, or the Local Setpoint Adjust knob is Out of Limits or has a Read error, then the Remote SPOffset is gated through to F8 by F6, and the range from F7 is set to 1, with the result that F8 adds the Remote SPOffset to the Remote Setpoint. Thus Remote SPOffset, K8, can either be a knob fail default, or it can be a value bound to a LonMark device. The Space Temp (S1) is normally the Local Space Temp (S9) via F9 but if the RemoteSpaceTemp K2 is bound to a Lon space sensor, the Lon Remote Temp Select bit 58,7 is set true and logic module G10 causes S1 to be the RemoteSpaceTemp K2. This will also happen if Local Space Temp has a Read or Out of Limits error. Thus RemoteSpaceTemp K2 can either be a sensor fail default, or it can be a value bound to a LonMark sensor. The real sensor S11 monitors the Supply Air Temp. Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 9

10 Data Sheet STRATEGY (continued) Setpoint Calculations (Diagram 3, strategy page 5) Diagram 3: Deadbands/Heating & Cooling Setpoints (strategy page 5) Summary: The current deadband is selected from the NOCC deadband (default 12 C), Standby Deadbnd (default 2 C), or OCC Deadbnd (default 1 C) according to the unit s occupancy state. The heating setpoint is the Setpoint minus half the current deadband, and the cooling setpoint is the Setpoint plus half the current deadband. heating setpoint=setpoint -½(deadband) cooling setpoint=setpoint +½(deadband) Detail: The function modules F10 and F11 produce a deadband according to the unit state; if Unit Occupied is true, the OCC Deadbnd K3 is selected, if Unit in Standby is true, the Standby Deadbnd K4 is selected, and if otherwise i.e. non-occupied, the NOCC Deadbnd K5 is selected. The function modules F12 and F13 add and subtract half the deadband from the Actual Setpoint to produce the Heating (F12) and Cooling (F13) loops setpoints respectively. 10 Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04

11 Data Sheet STRATEGY (continued) Heat/Cool Control (Diagram 4, strategy page 6) Diagram 4: Heat/Cool Control (strategy page 6) Summary: Heat and Cool Loops The heating and cooling sides are controlled by different control loops. Both heating and cooling loops are disabled by the Remote Shutdown setting, which effectively sets both loop outputs to zero. Boost Mode produces zero heating, and full cooling. The heating loop compares the Actual Space Temperature with the heating setpoint. The proportional + integral (P+I) loop will modulate the heating output to maintain a constant space temperature. As the temperature decreases below the heating setpoint the heating output will modulate open. The heating output will be modulated closed as the temperature increases above the heating setpoint. When the unoccupied mode is entered the heating loop s setpoint is decreased by the deadband mechanism explained above. The loop output is limited to the range 0 to 100%. The cooling loop compares the Actual Space Temperature with the cooling setpoint. The proportional + integral (P+I) loop will modulate the cooling output to maintain a constant space temperature. As the temperature increases above the cooling setpoint the cooling output will modulated open. The cooling output will be modulated closed as the temperature decreases below the cooling setpoint. When the unoccupied mode is entered the cooling loop s setpoint is increased by the deadband mechanism explained above. The loop output is limited to the range 0 to 100%. Error, E = setpoint - Space Temp G ( ) ( E) LoopOutput = G E +. dt I Where G = Loop gain I = Integral time constant The integral time constant is the time for which the loop output will have added to it an amount equal to product of the error and the gain (i.e. equal to the proportional part) under conditions of constant error. So if the error stays the same for the integral time constant, the loop output will double and will be 2G(E). The loops have the following default settings :heat loop gain = 20, cool loop gain = -20, both loop integral time constants =0 mins. These settings can be changed by text comms. The output from the loops (ignoring the integral action) are illustrated by the chart below: Output % 100% 0% 0 C Heating Demand Prop. Band Heating (2.5 C) Actual Setpoint Deadband Temperature Heat/Cool Control Cooling Demand Prop. Band Cooling (2.5 C) The heating loop will not operate until the Space Temp drops below the Setpoint by half the deadband (e.g. default = = 19.5 C during occupation). Similarly for cooling it must rise above by half the deadband. The loop gains are set to ±40 by default which gives proportional bands of 2.5 C (100/40). When set to defaults, during occupation, this will give 100% heat at 17 C, and 100% cool at 23 C (ignoring the effect of the integral term). The loop outputs are added together and then split into separate heating and cooling outputs to prevent simultaneous heating and cooling. Detail: The Remote Shutdown, W8, is used to disable the heating and cooling loops, L1, L2, by means of their setpoint selection, S, inputs by switching the loops into their occupied state. This forces them to use their occupied setpoints, O, which are set to 0 and 200 respectively. This ensures that the heating loop output will not rise unless the temperature drops below 0 C, and the cooling loop output will not rise unless the temperature exceeds 200 C. The Boost Mode, W1, switches the loops into manual, forcing them to output their manual levels, L, which are set to 0 and 100 respectively; this ensures there is full cooling only during boost mode. Otherwise the Actual Space Temperature is compared with the heating and cooling setpoints. The heating and cooling loop outputs are added by F14 to give -100 to +100 maximum cool to maximum heat. They are then rescaled by modules F19 and F17 so that F14 output of 0 to +100 gives Heating Demand (S4), 0 to 100%, and F14 output of -100 to 0 gives Cooling Demand (S5), 100 to 0%. Combining the loop outputs in this way prevents simultaneous heating and cooling. Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 11

12 Data Sheet STRATEGY (continued) Electric Heater Control (Diagram 5, strategy page 7) Diagram 5: Electric Heater Control (strategy page 7) Summary: The Elec Disable is normally off and the two stage electric heating is selected. Once the fan is enabled for heating, as the heating demand rises to 15 %, the Elec Stage 1 (channel 2) output is first switched on and as it further increases to 55%, the Elec Stage 2 (channel 3) is switched on. As the demand falls to 45% Elec Stage 2 is switched off, and as it further falls to 5% Elec Stage 1 is switched off. If Elec Disable is on, the HWS valve is enabled and the heating demand drives the valve. Detail: The gate function module F29 ensures that the fan has been enabled for heating (Heating Airflow SP Enable) before gating through the Heating Demand to the electric heaters. The hysteresis band function module, F20, generates a logic output when the Heating Demand exceeds 15%, and then stays high until the demand reduces to 5%. If Elec Disable, W3, is false, G15 connects the output of F20 to the Elec Stage 1 driver D2. The timer module G16 ensures that once the heating is switched off, it will not switch on again for at least 300 s (5 minutes). The hysteresis band function module, F21, generates a logic output when the Heating Demand exceeds 55%, and then stays high until the demand reduces to 45%. If Elec Disable, W3, is false, G17 connects the output of F21 to the Elec Stage 2 driver D3. The timer module G18 ensures that once the heating is switched off, it will not switch on again for at least 300 s (5 minutes). While the Elec Disable is switched off (i.e. electric heaters enabled) F34 connects zero to the HWS valve driver D4. However, when Elec Disable is switched on, the Heating Demand is connected via F34 to the HWS valve raise/lower driver D4 (channels 4 and 5). Note that after a reset (power or programmed) and at midnight the each Raise/Lower driver (HWS Valve and Damper actuators) will recalibrate the valve or damper position by driving the valve or damper to the calculated zero position (fully closed) and then overdrive for one complete driver period, (full scale drive time) to ensure the valve or damper is fully closed. It will then drive the valve or damper to the position required by the calculated demand. 12 Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04

13 Data Sheet STRATEGY (continued) Fan Speed Control (Diagram 6, strategy page 8) Summary A parallel fan is only enabled for a heating demand (as it sucks in the extract/hot air), whereas a serial fan is enabled for both heating or cooling demands (as it sucks in both extract/hot air and supply/cool air). Hence both types of fan are on for heating (Fan Enabled is set true) if the temperature falls below the heating setpoint (by 1 C). A serial fan is additionally on for cooling (Fan Enabled is set true) if the temperature rises above the cooling setpoint (by 1 C) during the Unoccupied state, and all the time that the unit is in Occupied or Standby. During these states the fan can be overridden off by Remote Shutdown. The fan is separately enabled if the Electric Heater is cooling down. Detail: F30 checks if the Space Temp rises above the current Cooling Setpoint by 1 C, and F22 checks if the Space Temp falls below the current Heating Setpoint by 1 C. G12 then takes these two conditions and drives the fan if cooling is required for a serial fan unit (W2=1) which is Unoccupied, or all the time for serial fan unit (W2=1) which is not Unoccupied (i.e. in Occupied, or Standby), or if heating is required at any time for either serial or parallel fan. G13 will allow the output of G12 to drive the fan if there is no Remote Shutdown, (W8=0). G13 also allows the fan to come on if the electric heater restart time isn t operating (i.e. the electric heater is cooling down). The output of G13 is monitored by Fan Enabled, I1, and drives the fan via the Fan Drive driver D1 (channel 1). The output of F22 is used to select the Heating Airflow SP Enable to drive the Damper and to enable the Electric Heaters. G19 is used to disable the damper if there is no cooling demand on the fan during the Unoccupied state. Diagram 6: Fan Speed Control (strategy page 8) Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 13

14 14 Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 Diagram 7 Damper Control (strategy page 9) Data Sheet

15 Data Sheet STRATEGY (continued) Damper Control (Diagram 7, strategy page 9) Summary: The damper is closed if there is no cooling and the unit is Unoccupied but for other conditions it is modulated according to the cooling or heating demand. To calculate airflow, the k constant must be set correctly. The k constant, K12, must be set to the box constant. The equation that relates the duct supply volume to the sensor reading, r, is V=k r lps where k is a constant that will be different for different types and sizes of box and for different inlet connections. The value is either supplied by the VAV box manufacturer or can be determined during factory testing or commissioning and must be set up in k constant. The Actual Air flow is calculated from the Differential Pressure sensor input. As the cooling demand varies between 0 and 100%, the cooling airflow setpoint varies between Min Airflow SP and Max Airflow SP. The Active AirFlow SP is normally the cooling airflow setpoint but if the temperature is below the heating setpoint, the Heating AirFlow SP is used. The damper is modulated according to the difference between the Actual Air flow and the active airflow setpoint. The VAV Damper driver fullscale drive time, D5(D) may have to be changed if the positions of the two actuator stops have been changed. The time should be measured in seconds from fully closed to fully open and the parameter changed if necessary using text communications i.e. D5(D=x). The damper may be set into Damper Override for commissioning purposes and its position directly controlled by the Damper Position knob. Detail: The Air DPressure (differential pressure) sensor, S14, has a range of 0 to 500 Pa. The air volume flow rate (lps) is calculated by function module F25. F25 calculates the flow rate by taking the square root of the pressure in Pa and multiplying it by the box k constant set by K12. The output of F25 is monitored by S8, Actual Air flow. F28 calculates the range between the Min Airflow SP (K13) and the Max Airflow SP (K14). F31 multiplies this by the cooling demand to define the required part of the range and F32 adds the Min Airflow SP (K13) to give the actual cooling airflow setpoint. Loop 3 compares the Actual Air Flow rate from F25 with the setpoint from F26. The VAV Damper Disable from G19 (see Fan Speed Control Section) selects the O setpoint of zero which switches the damper to zero if there is no cooling during occupation, but for any other condition the U setpoint from F26 is used. The Remote Shutdown, W8, puts the loop into manual override with its output level set by Damper Position, K16; this enables the damper position to be set manually. Loop 3 drives the damper via raise/lower driver D5 (channels 6, 7). This drives the integral actuator. Note that the loop 3 parameters (gain, integral, and reschedule time) should not be changed or the strategy performance may deteriorate. Note that after a reset (power or programmed) and at midnight the each Raise/Lower driver (HWS Valve and Damper actuator) will recalibrate the valve or damper position by driving the valve or damper to the calculated zero position (fully closed) and then overdrive for one complete driver period, (full scale drive time) to ensure the valve or damper is fully closed. It will then drive the valve or damper to the position required by the calculated demand. Using RD-IQL The parameters changed by RD-IQL are: S9, Local Space Temp (RD-IQL/K, /KOS) S10, Lcal SP Adjust (RD-IQL/K, /KOS) I12, Push Button (RD-IQL/KOS) The parameters displayed on RD-IQL are: S1, Space Temp (RD-IQL/K, /KOS) S2, Setpoint (RD-IQL/K, /KOS) S3, Occupancy (RD-IQL/KOS) The IQL must be set up as follows: Local Space Temp Type, S9(Y=6) (use RD) Local SP Adjust Type, S10(Y=6) (use RD) This should be terminated by a text comms reset command R(z=1) to write changes to flash and reset the unit; note that this command clears logged date and sets time to zero. Note that the use of the RD-IQL renders input 5 (alarm contact input) inoperative. The Htng AirFlow SP is set by K11 and if no special setpoint is required K11 should be set to be the same as the Min Airflow SP (K13). The Htng AirFlow SP is enabled when the actual space temperature is below the Heating setpoint by at least 1 C (see Fan Speed Control Section). S7, Active Air Flow SP, monitors the output of F26 which is normally the calculated actual cooling airflow setpoint, but will be the Htng AirFlow SP when Heating Airflow SP Enable is true. This then becomes the setpoint of Loop 3. Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04 15

16 Data Sheet INSTALLATION The installation is covered by the IQLVAV/xxx,../VAV,../USA Installation Instructions - TG ORDER CODES IQLVAV with Variable Air Volume Strategy (/VAV) SPECIFICATIONS Electrical Supply Power Inputs IN1 IN2 IN3 IN4 IN5 IN6 :24 Vac ±15%, 50/60 Hz :15 VA internal power plus power required by peripheral devices. Due to UL requirements for Class 2 devices, the power source used to power the controller cannot exceed 100 VA. :Thermistor input (S9). Scaled for standard IQ system thermistor (10 kω at 25 C). Scaling range 2.5 C to 60 C. Conversion accuracy ±0.25 C over range (10 to 30 C). :Potentiometer input (S10). Potentiometer input range 0 to 12 kω) has 0.1% resolution. Self calibrating 0 to 100 % over range used. Gives trim 0 to 1, which is added to sensor offset (default - ½) to give range (default - ½ to +½); this is multiplied by Offset Range (K15, default 2 C) to produce trim on setpoint (default -1 C to +1 C). :Thermistor input (S11). Scaled for standard IQ system thermistor (10 kω at 25 C). Scaling range 2.5 C to 60 C. Conversion accuracy ±0.25 C over range (10 to 30 C). :Pushbutton contact input (I9). (Volt free contact input. 5 Vdc supply via 10 kω. Wetting current 0.5 ma.) Input will bring the fan and heaters into operation when the contact is closed for at least 1 second (dependent on unit state) :Alarm (e.g. filter blocked) Input (I10). (Volt free contact input. 5 Vdc supply via 10 kω. Wetting current 0.5 ma.) :Integral differential pressure sensor (S14) measuring 0 to 500 Pa. The box constant is either supplied by the box manufacturer or can be measured and must be configured into the controller to convert pressure into flow. Outputs DO1 DO2 DO3 DO4/DO5 DO6/DO7 :Fan on/off triac output equivalent to 24 Vac solid state relay. Output rated at 0.7 A maximum at 24 Vac. :Electric Heater Stage 1 triac output equivalent to 24 Vac solid state relay. Output rated at 0.7 A maximum at 24 Vac. :Electric Heater Stage 2 triac output equivalent to 24 Vac solid state relay. Output rated at 0.7 A maximum at 24 Vac. :HWS valve triac outputs in raise/lower configuration equivalent to 24 Vac solid state relays. Output rated at 0.7 A maximum at 24 Vac. DO4 opens valve, DO5 closes valve. :Damper raise/lower outputs drive integral actuator. DO6 opens damper, DO7 closes damper. Version :This document applies to the following version: Firmware :v5.00 or later Strategy : release 02 Echelon Corporation. Echelon, LON, Neuron, LONWORKS are U.S. registered trademarks of Echelon Corporation. LONMARK is a trademark of Echelon Corporation. Trend Control Systems Ltd reserves the right to revise this publication from time to time and make changes to the content hereof without obligation to notify any person of such revisions or changes. P.O. Box 34, Horsham, West Sussex, RH12 2YF United Kingdom Website Telephone +44 (0) Fax (International) +44 (0) Fax (UK) +44 (0) trendinfo@novar.com Registered office. Novar House 24 Queens Road Weybridge Surrey KT13 9UX Registered in England No Variable Air Volume Strategy Data Sheet TA Issue 1/A 03/02/04