Siemens LMV37.400A2 - Air Pressure Switch Input (APS X3-02)

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Building Technologies Basic documentation LMV37.4... CC1P7546en
HVAC Products 6 Basic unit 01.12.2009
6.3.5 Air pressure switch (APS) X3–02
Input for connection of an air pressure switch.
Air pressure is anticipated after the fan has been switched on. If there is no air pressure
signal, the system initiates lockout.
The air pressure switch must have an NO contact.
If no air pressure switch is required (e.g. when firing on oil), a wire link to the fan output
must be fitted (between X3-02, terminal 1, and X3-05, terminal 1).
Caution!
The OEM must check to see whether the burner can be operated without using
an air pressure switch. This may necessitate a special approval, depending on
the application.
LMV...
Bild 277e /04 09
X3-02
Air pressure switch (LP)
L for air pressure switch (LP)
2
1
Figure 11: Air pressure switch (APS) X3-02
Error
code
Diagnostic
code
Meaning for the LMV37.4... system
3 0 Air pressure off
1 Air pressure on
4 Air pressure on – start prevention