What could be a potential cause of a furnace with no ignition?

A furnace with no ignition can indeed be caused by several factors, and in this case, the correct answer encompasses all the potential causes listed.

Firstly, a defective hot surface igniter can prevent the furnace from igniting. The hot surface igniter is responsible for heating up and creating a spark that ignites the gas. If it is malfunctioning or has failed altogether, the gas will not ignite, leading to a failure in starting the furnace.

Secondly, an inadequate power supply can also be a crucial factor. If the furnace does not receive the necessary voltage or current due to electrical issues, it might not be able to operate the components that facilitate ignition. This lack of power can be a result of wiring problems, blown fuses, or issues with the electrical panel.

Lastly, a faulty thermostat can interfere with the ignition sequence as well. The thermostat controls the heating cycle by signaling the furnace to turn on when the temperature drops below a set point. If the thermostat is not functioning correctly, it may not communicate with the furnace, resulting in a no ignition scenario.

Since all these issues can independently contribute to a furnace failing to ignite, recognizing that "all of the above" encapsulates the potential causes is crucial for diagnosing and resolving the problem effectively.