Viessmann Vitocrossal CRU 800 Service Instructions For Contractors page 34

Burner control unit
Burner control unit VUC 310
"Status" display "Service" display: Process information
4 Set speed
5 PWM variable
6 Actual speed
7 Gas pressure switch 1
8 Gas pressure switch 2 (not available for all boiler
types)
9 Air pressure switch
A Gas valve 1
B Gas valve 2 (not available for all boiler types)
Overview sub-menu to menu "6"
"Status" dis- "Service" display
play
Parameter
1 Maximum thermal load
2 Gas type
3 Altitude
4 Maximum boiler water temperature
5 Integral threshold value of control unit
(effective with integral method)
Do not adjust.
6 Runtime optimization
7 Motorised flue gas damper
8 Characteristics of burner control units
when gas pressure is too low
9 Burner start temperature differential (ef-
fective during minimum pause)
A Burner stop temperature differential (ef-
fective during minimum pause)
0 Reset all operating parameters to their
delivered condition.
Example: Temporarily display ionisation current in
the operating display
Press the following buttons:
1. S longer than 2 s; " " flashes.
2. until "5" is shown under "Service".
3. S to confirm; "5" is shown under "Status". "0" is
shown under "Service".
4. until "3" is shown under "Service".
34
(cont.)
Setting operating parameters:
—
Setting range/unit
% of rated heating out-
put
Cannot be changed
Cannot be changed
5 to 127 °C
1 to 255 K x min
0 = minimum pause
1 = integral method
0 = without flue gas
1 = with flue gas
0 = interlocked
1 = blocked
0 to 20 K
0 to 20 K
5. S "3" is shown under "Status". During operation,
Note
Pressing reset button R or switching the power con-
nection off and on again will return the operating dis-
play to the default display, showing the start and test
functions during burner start.
Unit/scale
%
%
n in 10/min
0 or 1
0 or 1
0 or 1
0 or 1
0 or 1
Delivered condition
100 %
Dependent on coding card
of burner control unit
101 °C
60 K x min
1
Do not adjust.
0
damper
damper
1
6 K
6 K
the ionisation current is shown under "Service":
≙
E.g. 30 3.0 A
µ