No Flame Formation At the Start of Heater Operation

No Flame Formation At The Start Of Heater Operation, Function

Shown On Models 215, 220:

Operating procedure
1 Heating mode has been activated:
- The green or red indicator lamp in the STH switch (N72s12 or S46) illuminates.

2 The combustion air blower (A6m2) and the circulation pump (A6m1) start up. The combustion air blower (A6m2) delivers almost at top speed. The coolant flows through the heat exchanger (2) and the heating and cooling circuit.

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

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:
"cold" = no flame -> the start is continued.

6 The heater element in the flame monitor heater element unit (A6r4) is switched on:
- The preheating time of approx. 30 sec. starts.

7 The preheating time is over
- The combustion air blower (A6m2) is switched off for 3 sec. and the STH or heater booster fuel metering pump (Y23) starts to deliver fuel.

8 The combustion air blower (A6m2) starts up again:
- Within the next 60 seconds, the combustion air blower (A6m2) and the STH or heater booster fuel metering pump (Y23) increase their rotational speed and output to full load. In the burner housing (1), the fuel and the combustion air form the fuel-air mixture.

9 Once the increase in the flow of combustion air and fuel delivery have been completed, the heater element of the flame monitor heater element unit (A6r4) is switched off, and the safety period begins for approx. 45 sec. to check the flame.

10 The safety period is terminated, the flame monitor heater element unit (A6r4) reports in its function as flame monitor:
"cold" = no or insufficient flame formation

11 The STH or heater booster control module (A6n1) initiates a one-off second start.
- the STH or heater booster fuel metering pump (Y23) is switched off and
- heater short delayed switch-off is activated for approx. 60s.

12 Heater short delayed switch-off has finished and second start with flame monitor inquiry, preheating time and safety period commences.

13 The flame monitor heater element unit (A6r4) again reports "cold" in its function as flame monitor.

14 The STH or heater booster control module (A6n1) triggers heater malfunction delayed switch-off with subsequent malfunction shutoff for approx. 120 s:
- the STH or heater booster fuel metering pump (Y23) is switched off.

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

16 Malfunction delayed shut-off has finished:
- 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) is extinguished.

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.