The answer to 'how often to replace heat exchanger' is that the heat exchanger in an HVAC system typically lasts 15-20 years with proper maintenance. The heat exchanger is a critical component that transfers heat from the combustion process to the air circulating through the system. Over time, normal wear and tear can cause cracks or holes to develop in the heat exchanger, which can lead to dangerous carbon monoxide leaks.
It's important to have a qualified HVAC technician inspect the heat exchanger annually during a tune-up or maintenance visit. They will check for any signs of deterioration and let you know if replacement is recommended. Replacing the heat exchanger before it fails completely can help prevent a costly breakdown and ensure the continued safe operation of your heating system.