Laars MagnaTherm HTD Series Installation And Operation Instructions Manual

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Laars MagnaTherm HTD Series Installation And Operation Instructions Manual Manual pdf 110 page image

LAARS Heating SystemsPage 106Table 23. BIC Status and LMV Status10.E OperationThis unit utilizes three (3) separate controllers tomanage system functions, burner management and air/fuel ratio control:- Burner Integrated Control (BIC)- Linkageless Modulating Valve (LMV)- Oxygen Controller (O2C)These controllers communicate with each othervia voltage and current signals, and serial digitalcommunication using Modbus protocol. The BIC alsocommunicates with the touch screen display and alluser inputs.When there is a call for heat the BIC will provide anenable signal to the LMV which tells the LMV to initiateburner operation. For this signal to be sent and actedupon, the safety circuit must be satisfied and bothcontrollers must be in standby mode.The system pressure sensors, which measure theoverall system pressure drop must also read zero inorder for the Safety Status to be verified.The Safety Circuit status can be verified on theServices/Digital I/O screen. Once the LMV is enabled itwill proceed through the startup states listed in Table 23until it gets to Run. Once in Run, the LMV will receivea firing rate demand from the BIC and position the fueland air dampers and blower speed accordingly.After the burner has been on for two (2) minutesthe oxygen trim loop will be enabled and the blowerspeed will be adjusted to maintain the preset oxygenconcentration in the boiler exhaust.If a pilot flame is not detected during the “verify pilot”stage, the LMV will skip to postpurge and then backto Blower On to retry. Four attempts will be madebefore the LMV will Lockout. Once in Lockout, a hardreset is required by pressing the Reset Button on thetouchscreen.If the main flame is not detected during the “VerifyMain Burner” stage, the LMV will skip to postpurge andthen back to Blower On to retry the pilot and then mainburner ignition. Only one (1) retry will be attemptedduring a given call for heat. If main flame ignition doesnot occur on the second attempt, the LMV will lockout.If the call for heat is satisfied normally, the BIC willremove the enable signal and the LMV will de-energizethe fuel valves and enter postpurge. Any time thereis an interruption of the BIC safety circuit, both theLMV enable signal and LMV safety loop signal will beremoved, triggering a burner shutdown. Along withthe circuit components identified in the System LadderLogic, the system differential pressure is continuouslymonitored while the burner is in operation.If the system differential pressure exceeds it’s setting,the Safety Status will be disabled shutting down theburner. The cause of the safety shutdown will bedisplayed on the touchscreen. A manual resetis required to restart the system once the faultcondition has been corrected.BIC Status LMV StatesPhase PhaseStandy 12 StandbyCall For HeatLMV Enable22 Blower On24 Component CalibrationPressure Transmitter Verification 30 Prepurge36 Move to Ignition Position38 Igniter OnRead (via Modbus) ACC State 40 Pilot Onand Display atTouchscreen42 Verify Pilot50 Main Fuel On52 Pilot Off/Verify Main Burn60 RunFan Speed Governed byController Demand SignalEnd Call for HeatLMV Disable70 Post Purge74 ShutdownStandby Standby