The picture above shows the top of a water heater that is connected to a chimney that is not working properly. When the chimney doesn’t work, the flue gasses (like carbon monoxide) from your heating appliances spill back into your living area. If the top of your water heater is discolored or rusted like the picture above, there’s a pretty good chance you have some sort of problem with your chimney. If this is what your water heater looks like, schedule a chimney inspection ASAP.