I just bought a home that came with a Preway FB26 FAC. This is a fireplace stove unit. Seems to be installed correctly. On the chimney stack there is a lever to open and close the flu. I got that. However, on the bottom right side there is also a lever labeled open and close. Also, on the back there seems to be an opening to pour in water. What could this be for? Any help would be greatly appreciated.