HONEYWELL 7800 series combustion controller

2. Run/Test Switch

Located at the top of the relay module, used for debugging and maintenance:

Blowing stage: Placing it in the TEST position can pause the blowing process for easy inspection of high or low flame positions

Stable ignition period: When placed in the TEST position, the timer can be paused for ignition reduction testing, while activating the 15 second flame extinguishing timer

Operation phase: Placing it in the TEST position can drive the modulation motor to the low flame position

Attention: After debugging is completed, the switch must be restored to the RUN position.

Flame signal measurement and diagnosis

The flame signal strength can be measured at the flame amplifier test point through the keyboard display module (KDM) or a dedicated voltmeter. The signal strength requirements depend on the specific flame amplifier model and the type of flame detector equipped.

The 7800 series module has a comprehensive system self diagnostic function, and fault codes can be displayed through KDM or indicated by a combination of LED indicator lights, making it easy to quickly locate the root cause of the problem. Typical reasons for locking include:

Pre ignition interlock is disconnected during blowdown period

Flame signal detected during purging

The high fire switch or low fire switch is not closed within the specified time

The wind pressure switch is not closed within 10 seconds

Flame loss during the main fire test period

Internal system malfunction or missing/damaged purge timing card