What is the likely issue if the main burners will not ignite even though a pilot light is present?

When the main burners will not ignite despite having a pilot light, one likely issue could be that the ignition system is not confirming the presence of a pilot flame. Most heating systems require a safe and reliable method to ensure that the pilot light is adequate for igniting the main burners. This is often facilitated by a flame sensor or other electronic control that detects the pilot flame. If this system fails to recognize the pilot light, it won’t send the necessary signal to open the gas valve for the main burners to ignite, thus preventing the heating system from functioning properly.

In situations where the ignition system cannot prove the pilot flame, even if the pilot is technically lit, the gas supply to the main burners will remain off as a safety precaution. This design is critical to prevent unsafe conditions that could arise if gas were to flow without a flame present.

Other potential issues, such as problems with the gas valve, blower motor, or thermostat, may also lead to heating system failures. However, these would typically manifest in distinct ways, such as the entire system being inoperative or not providing heat at all, rather than the specific scenario of the main burners not igniting while a pilot light is present.