Technical data

Fig. 301:Functional sequence (heaters with control unit 1572)
A
B
C
D
E
F
G
16 12 14 161412
13 15 13 15
1
2
6
8
2
9
6
10
3
5
3
7
1s 12s12s 30s 90s1s12s
max.
max.
11
1s12s30s 90s1s
A H1 Operating indicator light
B E1 Heater cartridge
C M2 Circulation pump
D U1 Igniter box
E M1 Combustion air fan
F Y1 Solenoid valve
G B1 Flame sensor
1 Switch on
2 Start
3 Combustion operation
5 Temperature sensor – upper switching
threshold
6 Flame sensor – dark
7 Control idle
8 Temperature sensor – lower switching
threshold
9 Switch off
10 Heater – off
11 Nozzle block preheater
12 Start-up
13 Foreign light check
14 Pre-ignition
15 Safety period
16 Run-down
3 Functional Description Thermo 230 / 231 / 300 / 301 / 350
304
– temperature sensor short circuit during control idle.
– temperature sensor open circuit during combustion.
– flame sensor short circuit during combustion.
– solenoid valve short circuit during combustion.
Malfunctions during run-down:
Detection of a flame after more than 30 seconds after start
of run-down with the circulation pump and combustion air
fan maintaining operation for the following 90 seconds.
Malfunctions by overheating:
Overheating results in deactivation of the heater by the
temperature limiter. After cool down of the unit and
correction of the fault the button of the temperature limiter
must be reset.
An error reset for a new start standby is achieved by
switching the heater off and on again.