Question: I'm in the process of buying a 75 year old house that originally had some sort of gas burning unit inside the fireplace. The house has an original chimney and on the backside of the firebox there is a ceramic plate (now cracked) with a 4" hole vented into the chimney. The sides of the firebox are brick but the top has exposed wood construction and no flue as it was never intended to burn wood. I'm getting differing opinions as to whether or not it is safe to put either a vented or unvented gas log unit in there mainly because of the heat and wood combination. What can I do to make this safe to burn gas? Is that 4" hole big enough to vent a vented gas unit? Would an unvented unit be cheaper to install in this situation, and what to do about that wood?? Answer: Here's the scoop: It is probably unsafe to put any gas log into such a fireplace. All gas logs, vented or unvented, are made to be installed into a function WOOD BURNING FIREPLACE..which we can assume yours is not. The solution? Install a small gas burning appliance, complete with it's firebox, into the chimney opening or in from of it (if it's a stove). Either use a vent free, or use an aluminum liner or b-vent to vent the appliance.