If you’re asking this question and looking for answers online, it’s probably because you think you’ve found corrosion on your gas furnace. Or perhaps you’re curious because you have an older furnace and you want to know what can happen to it as it ages. Whatever the reason, we’re glad you asked because corrosion is an important topic when it comes to furnaces.
So the simple answer is, Yes, a gas furnace can corrode. It’s not something you want to happen, and it’s often a warning that the furnace needs to be replaced.