Which device is used to verify that the combustion blower is operating, and is connected to the damper system?

Which device is used to verify that the combustion blower is operating, and is connected to the damper system?

• A. Pressure switch
• B. Thermocouple
• C. Flow switch
• D. Temperature sensor

Answer: (A)

Pressure switch. It checks the draft created by the combustion blower (inducer) and confirms there’s proper venting before the burner is allowed to ignite. When the inducer runs, a negative pressure signal is generated in the vent path; the pressure switch diaphragm senses this and closes, sending a signal to the control so the burner can operate and the damper can stay in (or move to) the correct position. If the vent isn’t drawing correctly—due to a blocked vent, faulty inducer, or a damper that isn’t open—the pressure switch won’t sense the required pressure and will prevent ignition, keeping the system safe. The other devices measure flame presence, airflow, or temperature, but they don’t verify blower operation tied to the damper in the same safety-critical way.

Pressure switch. It checks the draft created by the combustion blower (inducer) and confirms there’s proper venting before the burner is allowed to ignite. When the inducer runs, a negative pressure signal is generated in the vent path; the pressure switch diaphragm senses this and closes, sending a signal to the control so the burner can operate and the damper can stay in (or move to) the correct position. If the vent isn’t drawing correctly—due to a blocked vent, faulty inducer, or a damper that isn’t open—the pressure switch won’t sense the required pressure and will prevent ignition, keeping the system safe. The other devices measure flame presence, airflow, or temperature, but they don’t verify blower operation tied to the damper in the same safety-critical way.