Viessmann MatriX Service Instructions Manual page 41

Gas burner control unit connection diagram
Legend
A 1 Gas burner control unit MPA 51
A 2 Display unit with reset function
B 1 Flame monitoring through
ionisation current
B 2 Safety chain jumper
F 1 Main fuse
F 2 High limit safety cut−out
F 4 Gas governor minimum pressure
F 6 Air pressure limiter
H 1 Total operating hours
H 2 Fault reporting
H3 Operating hours
modulation
lower rated output/
higher rated output
K 1 Relay contact
M 1 Fan motor with PWM selection
and feedback
S 1 Main ON/OFF switch
(in the control unit)
S 2 Thermostat
S 3 Output control
(in the control unit)
T 1 Ignition device
X 1 Actuator for rotary damper
Y 1 Gas fuel safety valve
Gas burner control unit connection diagram
(cont.)
41