What issue could arise from using an incorrect gas type for a heating system?

Using an incorrect gas type for a heating system can significantly impact the system's performance and safety. When the wrong type of gas is introduced, it can lead to improper combustion. This typically results in flames that are not only the wrong height but also possibly the wrong color and stability, indicating inefficiency and potential danger.

In contrast, the other issues listed also present real risks, such as inefficient operation and gas leaks, but they do not specifically highlight the direct effect of flame characteristics resulting from incorrect gas use. Moreover, stating that the system will require no adjustments overlooks the inherent need to make necessary modifications to ensure safe and proper operation with the correct fuel type. Understanding this aspect of gas heating systems is crucial for maintaining safety and efficiency in home heating applications.