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Building Technologies   Basic documentation LMV37.4...  CC1P7546en 
  7 Basic unit LMV37.4  17.12.2018 
7.5.4.10. Continuous fan 
 
With burners that can be damaged by heat (e.g. several burners using the same 
combustion chamber), continuous purging may be required. In that case, the fan 
operates continuously in all phases. 
For that purpose, the fan motor contactor is to be connected to X3-05, pin 3, tapped 
after the unit fuse and the safety loop. 
For checking the air pressure switch, a pressure switch relief valve must be connected 
to fan motor contactor X3-05, pin 1. When output X3-05, pin 1, is activated, the relief 
valve diverts the fan pressure to the air pressure switch and, when deactivated, ensures 
that no pressure is fed to the switch. 
 
Example: 
 
LMV...
Bild 296e/1010
X3-05
X3-02
 
Figure 37: Continuous fan