Question: I have a Free Heat Machine Fireplace Insert in my masonry fireplace. I would like to install LP Gas Logs. ( A free heat machine is a set of glass doors with stainless steel tubes attached to the top and bottom of the doors. The tubes draw room air in at the bottom. The room air is heated by the fire and vented back into the room through the top of the tube. The room air is moved with a blower.) The burner will fit below the tubes, and the logs will lay on the tubes. Is this safe to do? Answer: It may or may not be safe, but since it is not a listed function of the unit, you probably should not do it. If it was done, the doors would have to remain open full time since vented gas logs require a full opening. Best to remove the Free Heat Machine. If you want heat, install a vent-free log or a complete gas fireplace insert.