To check for an obstructed flue pipe on an induced draft furnace, a technician should use which tool?

Using a manometer is essential for checking an obstructed flue pipe on an induced draft furnace. This tool measures the pressure differential in the flue system, allowing the technician to determine whether the flue is functioning correctly. Proper draft is crucial for venting combustion gases outside the building; any obstruction can create negative pressure, resulting in inefficient operation or dangerous backdrafting of gases.

By using a manometer, the technician can assess whether there is adequate draft pressure in the flue. If the readings indicate a significant drop in expected pressure, it may suggest that there is a blockage or obstruction present, needing further inspection and potential cleaning or repairs to ensure safe operation of the furnace.

In this scenario, the role of a manometer in assessing the system's pressure helps maintain safety and efficiency, which are key considerations when troubleshooting gas furnaces.