Here’s how to close a fireplace: Your fireplace may have dampers which allows an effective flow of air, circulating from inside of your house out towards the chimney flue. If your dampers are installed from the mouth of the fireplace, within your reach, then your dampers should be visibly open or closed. If your dampers are not visible, it may be located on the top of your chimney. In this case, you may have to use a peripheral method (view through the chimney, or view from the roof where the dampers are visible) to determine if it is open or not. You may need another person to monitor the dampers while another person turns the crank for the damper. After all, you don’t want to get any fireplace snow.