To prove that the combustion blower motor is operating before ignition, which device would be used?

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Multiple Choice

To prove that the combustion blower motor is operating before ignition, which device would be used?

The device used to prove that the combustion blower motor is operating before ignition is the pressure switch. When the inducer/combustion blower starts, it creates a draft and a specific negative pressure in the combustion chamber. The pressure switch is wired to sense that pressure difference; once the proper draft is detected, the switch closes and signals the control to allow ignition. If the switch doesn’t close, the gas valve remains shut to prevent unburned gas from accumulating. A flow switch checks for air movement but isn’t the standard interlock used to confirm the blower is running before ignition in many systems. A thermostat only controls temperature demand, not blower proof. A pressure gauge measures pressure for diagnosis, not as part of the pre-ignition safety interlock.

The device used to prove that the combustion blower motor is operating before ignition is the pressure switch. When the inducer/combustion blower starts, it creates a draft and a specific negative pressure in the combustion chamber. The pressure switch is wired to sense that pressure difference; once the proper draft is detected, the switch closes and signals the control to allow ignition. If the switch doesn’t close, the gas valve remains shut to prevent unburned gas from accumulating.

A flow switch checks for air movement but isn’t the standard interlock used to confirm the blower is running before ignition in many systems. A thermostat only controls temperature demand, not blower proof. A pressure gauge measures pressure for diagnosis, not as part of the pre-ignition safety interlock.

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