Which of the following symptoms may indicate a cracked heat exchanger?

Increased furnace cycling is indeed a symptom that may indicate a cracked heat exchanger. When a heat exchanger is compromised, the system may struggle to maintain proper temperatures and can overheat, prompting it to cycle on and off more frequently as a safety measure. This cycling can lead to inefficient heating and may require the system to work harder to reach the desired temperature, which can put additional stress on the components.

Identifying this symptom is crucial because a cracked heat exchanger poses safety risks, including the potential for carbon monoxide leaks. This is why observing changes in how often the furnace cycles is important for diagnosing issues with the heat exchanger. Regular maintenance and inspections are recommended to ensure that any such problems are caught early and addressed appropriately.