Your gas furnace needs to be kept in good shape so it's not expensive to operate and so no damage happens that could let carbon monoxide escape. You should hire a heating contractor to do preventative maintenance at least once a year and to do repairs when problems arise.
It's important to care for all of the parts, especially in the combustion area, so the heat exchanger doesn't crack. Here are some furnace problems that can cause the heat exchanger to crack and how they can be prevented.
Restricted Airflow Causes A Furnace To Overheat
If restricted airflow is caused by a dirty filter, you can take care of that problem yourself by changing the filter. Having annual maintenance where the heating contractor cleans your furnace and ensures all the parts are working properly is a good way to prevent problems with restricted airflow, too. Also, air needs to circulate freely around your furnace, so don't stack things that could block air around the furnace.
Restricted airflow might even interfere with the way the combustion process works in your furnace. So keeping your furnace clean is an important way to protect the heat exchanger from damage.
Old Age Causes Parts To Wear Out
If your furnace is old, the heat exchanger may wear out due to stress on the metal or rust holes. When this happens, it's time to get a new furnace. Heat exchangers aren't repaired. If your furnace is fairly new, an exchanger might be replaced, but when your furnace is old, the heating contractor will probably recommend replacing the entire furnace.
When you have annual furnace maintenance, the heating contractor can look for signs of wear and tear so you know when your furnace is near the end of its life. This allows you to replace it at your convenience rather than in an emergency situation.
Ducts Are Too Small
If you recently put new ducts in, they may not be the right size. If they're too small, the airflow might not be enough for your furnace to operate without struggling or overheating. If the ducts are not large enough, your heating contractor has to replace them. The same is true if your furnace is too big or too small. Issues with short-cycling can affect the heat exchanger and cause metal fatigue that leads to cracking.
When your heating contractor finds a crack in the heat exchanger, they'll want to understand why. If they replace the heat exchanger, the new one might crack too if the cause is not found and corrected.
For more info, contact a local heating contractor.