Changing a hot water prematurely is probable less expensive than having one blow the bottom out and flood whatever area it is in. I don't have a basement, so my central unit and water heater share a utility closet in the hallway sharing a wall with a bedroom. It's a pretty bad design flaw, as during the summer of 110°+ temps, it is unnecessarily heating the house. IR temp shows that shared wall from the bedroom side over 90° radiating into that bedroom. </rant>