Flame Monitor Fault During Start of Heater Operation

Flame Monitor Fault During Start Of Heater Operation, Function

Shown On Models 215, 220:

Operating procedure
1 Heater operation has been triggered:
- The green or red indicator lamp in the STH switch (N72s12 or S46) illuminates.

2 The control and operating module (N18, N22 or N22/7) is set to stationary heating mode.

3 The combustion air blower (A6m2) and the circulation pump (A6m1) start up. The combustion air blower operates approximately at its maximum rotational speed. The coolant flows through the heat exchanger (2) and the heating and cooling circuit.

4 Coolant temperature < 30 degrees C:
- The ventilation blower is switched off.

5 An inquiry to the flame monitor is started for 1 second, and the flame monitor glow pin unit (A6r4) signals the following in its function as flame monitor:
"hot" = flame

6 The STH or heater booster control module (A6n1) evaluates the signal as a malfunction in the flame monitor glow pin unit (A6r4) since there cannot be a flame yet and immediately triggers a heater malfunction delayed switch-off for approx. 120 sec. with subsequent malfunction shut-off.

7 The control and operating module (N18, N22 or N22/7) switched from stationary heating mode to normal operating mode.

8 Malfunction delayed switch-off is terminated:
- The combustion air blower (A6m2) and the recirculation pump (A6m1) are switched off.
- The green or red indicator lamp in the STH switch (N72s12 or S46) goes off. Malfunction shutoff is present.

NOTE: In order to restart, the STH heater or heater booster must be switched off and on again at the STH switch (N72s12 or S46) after the malfunction has been remedied.