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Building Technologies   Basic documentation LMV37.4...  CC1P7546en 
  9 Connection to load controllers  17.12.2018 
 
Shifting multistage operation (OPEN pin 3 / CLOSE pin 2) 
 
Using a simple thermostat, a modulating burner can be operated in shifting 2-stage 
mode. In that case, there must be a firm connection between terminal CLOSE and the 
live conductor (L), and terminal OPEN must be connected to the thermostat or the load 
controller. 
If OPEN is inactive, the active CLOSE terminal drives the burner to low-fire. 
If OPEN becomes active, priority is given over terminal CLOSE so that the output is 
increased by driving the burner to high-fire. 
 
LMV...
7546z203e/0913
X5-03
L
ON/OFF
Load controller (LR) (OPEN)
Load controller (LR) (CLOSED)
Load controller (LR) (ON/OFF)
 
Figure 72: Shifting multistage operation (OPEN pin 3 / CLOSE pin 2) 
 
Parameter 205 is needed to interchange usage of the load controller contacts for 
multistage operation. In that case, the burner switches to the third stage when input 
Stage 2 is active (load controller OPEN). This has no impact on modulating operation. 
 
No. Parameter 
205 
Function Load controller contacts multistage 
0 = standard 
1 = stages interchanged 
 
Modulating    Standard  Stages interchanged 
X5-03 pin 1  ON / OFF  Low-fire  Low-fire 
X5-03 pin 2  Close  Signal Close  Signal Close 
X5-03 pin 3  Open  Signal Open  Signal Open 
 
2-stage    Standard  Stages interchanged 
X5-03 pin 1  ON / OFF  Stage 1  Stage 1 
X5-03 pin 2  Close  Stage 2  Stage 1 
X5-03 pin 3  Open  Stage 2  Stage 2 
 
3-stage    Standard  Stages interchanged 
X5-03 pin 1  ON / OFF  Stage 1  Stage 1 
X5-03 pin 2  Close  Stage 3  Stage 2 
X5-03 pin 3  Open  Stage 2  Stage 3