House is 20 years old. Wood burning fireplace with this insert or built-in? Two fans on the side behind the louvers, fan is controlled by dial on the wall. We wish to replace this with a gas insert but we aren't sure what we have. There's a damper on the inside. Our neighbor calls it a Heatilator. Any idea where to look for model, make, serial # info? Not sure if we have a masonary chimney or not. What a can of worms we have opened. Thanks in advance for your help!