The answer to 'why is my heat exchanger short cycling' is that there are several common causes, including a malfunctioning thermostat, issues with the blower fan, or a problem with the heat exchanger itself. Short cycling, where the furnace turns on and off rapidly, can be caused by the heat exchanger overheating and shutting down to prevent damage.
Some key symptoms of a short cycling heat exchanger include the furnace turning on and off frequently, inconsistent heating throughout your home, and higher than normal energy bills. Causes can range from a clogged air filter restricting airflow to a cracked or damaged heat exchanger. It's important to address the root cause to prevent further damage and ensure safe, efficient heating.