Unusual fireplace firebox

Appears to be a professionally installed fireplace with glass doors and fan driven air circulation around the outside of the firebox, however, there is no damper that I could find, and the top of the firebox is a steel plate that extends over the flue, but about 6 inches below it. The plate can be lifted by hand. Anybody ever see anything similar?
Is no damper a big deal if the doors close tight?