If the boiler inspection device (BIDS) fogs up during a furnace inspection, what is the probable cause?

The fogging of the boiler inspection device (BIDS) during a furnace inspection is most likely due to excess moisture in the air. When a device designed for inspection fogs up, it indicates that water vapor in the air is condensing on the cooler surface of the device, which is often a result of high humidity levels.

In a furnace environment, if conditions are not properly controlled, moisture can accumulate, especially if there is an issue with ventilation or airflow. High furnace temperatures can actually reduce the chances of fogging, as warmer air holds more moisture without condensation. Insufficient air supply could lead to combustion issues, but it wouldn’t primarily cause fogging of the inspection device. Similarly, the presence of fuel oil in the furnace may produce fumes, but it does not directly correlate with moisture accumulation that leads to fogging.

Understanding the causes of condensation helps in diagnosing issues within the furnace operations and ensuring optimal performance. This context highlights the importance of monitoring humidity levels and maintaining proper ventilation to prevent such occurrences.