RBI FUTERA XLF Series Control Manual
Also see for FUTERA III Series: User's information manualInstallation & operation manualInstallation and operating instructionsManual
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CONTROL METHODS HeatNet Control V3Page 23external control is not present, has failed, or needs to beenabled or disabled. A Member can override the H-Netcommands using this input.Priority 3If a HeatNet (H-Net) Network cable is connected betweenboilers, and one is configured as a MASTER (requiresHEADER sensor), then the MEMBER boilers will becontrolled over the network by the MASTER.Priority 4The 4-20mA/0-10VDC input in tandem with the 4-20mAREMOTE ENABLE input is next. Any signal over 4.02mAor 2.01VDC will start and operate the boiler if theREMOTE ENABLE is closed.Priority 5The lowest Priority is using the boiler as (2) stagesHIGH/LOW. These are the T1 and T2 inputs.Each of these control methods will now be explained inmore detail:Heating Method 1HEAT DEMANDClosing a relay contact, switch, or jumper across the HEATDEMAND input will enable this method. This methodallows operation as a setpoint control. As a setpoint control,the Master (defined by having a common system headersensor), on the H-Net network can command the boiler firerate of all Member boilers. The Master can call as manyboilers that it has available (boilers are auto-detected overthe H-Net cable by the Master) to meet its SYSTEMSETPOINT. The H-Net cable must be connected and willcause the amber light on the communications board to flash.The amber light indicates an H-Net Master is broadcastingcontrol information and a system heartbeat.The AA terminal, the FAILSAFE mode active, 4-20mA atPRIORITY: HIGHEST, and the HEAT DEMAND input(LOCAL) on a Member, are the only inputs that willoverride the H-Net control.Figure 18 Heat demand inputMEMBER: Close to run at Local setpoint.MASTER: Close to control all boilers andrun at System setpoint.Master boilerThe MASTER boiler controls the system using a PIDalgorithm. Once the boiler is started, a PID algorithm isused to produce a modulation percentage value from 0-100%. This percentage is converted to a PWM, (P)ulse(W)idth (M)odulation signal by each boiler. Thetemperature of the water is maintained by sending thisPWM signal to the Variable Frequency Drive, which in turncontrols the blower motor. Since the main fuel valve is air-fuel coupled to the blower, the speed of the blower providesthe firing rate.Member boiler(s)A Member (lacking a common system supply headersensor) boiler may also be controlled by the HEATDEMAND input (LOCAL mode). The Member boiler willthen ignore commands from the Master and maintain itsown LOCAL SETPOINT at its supply sensor. This can beviewed as a manual override on a Member boiler. Be sure toobserve the proper use of a Common System Damper (See:AUXILIARY FUNCTION OPTIONS section) and anysystem pumps or system common interlocks.Features of the HEAT DEMAND input include:1. The control is designed to predict when to start andstop the boiler and keep the setpoint in, or as close tothe control band as possible. If PREDICTIVE STARTis enabled, the boiler may start when it is in the bandand not below it. This will help to maintain a moreaccurate temperature relative to the setpoint. See also:ADVANCED SETUP: FIRING MODE: PREDICTIVESTART: to disable this feature.2. The control can also use the Outdoor Reset feature.This feature allows the setpoint to be changedautomatically based on the outside air temperature. Ifthis feature is used, the control input: OR OVR(OUTDOOR RESET OVERRIDE), can be used tooverride the Outdoor Reset feature and run from thelocal setpoint. A contact closure on the ‘AA’ input canalso override this method.3. There is also support for a common system damper,Heat Exchanger support, and starting the Master firstfor common venting. For an overview of each of themenu settings see: DEFAULT SETTINGS section.Heating Method 2STAGE Control T1-T2The boiler can also be operated in 2 separate stages usingthe inputs T1 and T2 inputs. Its intended use is with anexternal stage controller with no analog or modulationoutputs. Closing only one of these contacts tells the boiler tooperate at MINIMUM FIRE. |
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