Combustion Chamber Pressure Monitoring Function (Ldw2) - Viessmann MatriX Service Instructions For Contractors

Air pressure switch

Combustion chamber pressure monitoring function (LDW2)

A B
Fig. 33
A Reset button R
Air pressure switch 2
B
(cont.)
To monitor the combustion chamber pressure, the
switching threshold of air pressure switch 2 (LDW2) is
monitored in all operating phases (except during the
safety and stabilising time).
Air pressure switch triggers a fault shutdown at the
C
burner control unit under the following circumstances:
If the combustion chamber pressure is outside the
■
permissible range in the pre-purge phase, in control
mode or in the post-purge phase after 2 attempts.
The fault shutdown is indicated by fault code "F FB"
on the burner control unit display. Reset the burner
control unit by pressing reset button R (
ter "Display and programming unit" on page 29.
Rated heat- Rated heat in-
ing output put
P Q (H ) [net
max max i
(50/30 °C) cv]
in kW
400
500
630
Note
Check control cables:
Connection and kink-free routing
■
Application and seating of retaining clips
■
Functions
). See chap-
A
LDW2 setting value
in kW in mbar (kPa)
381
474 5 (0.5)
593
↑
43