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Siemens Building Technologies  Basic Documentation LMV5...  CC1P7550en 
HVAC Products  6 Temperature or pressure controller (internal load controller LC)  13.08.2004 
 
6.4 Control (characteristics) 
 
The load controller can work in 2 different operating modes: 
• Modulating, or 
• Multistage 
 
With electronic fuel / air ratio control, modulating or multistage mode must be selected, 
depending on the type of burner. 
 
Parameter:  Operation Mode (Two-stage / Three-stage / Modulating) 
 
6.4.1 Integrated 2-position controller (C = ON / OFF) 
 
The integrated 2-position controller transmits to the burner control section the internal 
information «Heat demand controller» (C = ON / OFF). 
 
Modulating mode: 
C = ON when:  Actual value ≤ (setpoint ± SD_ModOn) 
C = OFF when:  Actual value > (setpoint + SD_ModOff) 
 
Multistage mode: 
C = ON when:  Actual value ≤ (setpoint ± SD_Stage1On) 
C = OFF when:  Actual value > (setpoint + SD_Stage1Off) or 
C = OFF when:  Actual value > (setpoint + SD_Stage3Off) = low-fire; always applies 
if none of the 2 thresholds Q2 or Q3 has been exceeded 
 
Note:  When «SD_*_On» is positive, the switching differential lies above the setpoint. 
When«SD_*_On» is negative, the switching differential lies below the setpoint 
(LC software version V01.40 or higher). 
 
Parameters:  SD_ModOn 
  SD_ModOff 
  SD_Stage1On 
  SD_Stage1Off 
  SD_Stage2Off 
  SD_Stage3Off 
 
Operating mode 
General 
Switching differentials