I recently saved a new customer a bunch of money. He called to tell me that his old water heater had given up the ghost and he probably just needed a new one. I drove out and took a look, but I couldn't find anything actually wrong with the equipment except it needed a good cleaning.
A gas water heater requires unrestricted airflow, a clean pilot line, and a clean burner area in order to efficiently heat the water. There are safeties in place to turn off the burner if it cannot burn the gas cleanly and exhaust the space.
So, I gave the whole unit a good cleaning and it started heating water again properly.
It's important to periodically perform maintenance on all your plumbing equipment. Your water heater is a very expensive appliance to operate. If it's not clean, it may keep working but do it very inefficiently and cost you a bunch more money every month.
As a plumber, taking care of these things is my specialty. You can always call me at (405)473-2769 if you have any questions or concerns about your home's plumbing.