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Gas insert to gas chimney question

I have a fireplace that at one point had a natural gas enclosed insert in it. The insert has been removed. I would like to use the natural gas and just put a regular cement log fire in the fireplace. The chimney has a metal flexible tube that goes to the roof and my question has to do with that. Is it possible to put a vent like a giant funnel on the end of that tube to vent the gas from the fireplace? I don’t want to have to remove the tube and change the top of the chimney. I don’t know if it’s some thing that is legal or feasible. 


  • Bob Harper
    Bob Harper Member Posts: 1,040
    No, you cannot. A vented gas log vents essentially the same as wood. The fireplace and chimney must be suitable for the class of service. When you change the fuel or efficiency, which you are doing in this case, it triggers a level II inspection per NFPA 211. This will necessitate removing the flexible liners so it can be swept if need be then video scanned. The vented gas logs must be listed to ANSI Z21.60a and installed per mfr. This includes removing the damper or blocking it wide open if you're using a remote control. Even on manual control you must maintain the permanent minimum net free opening specified AND open the damper fully each time you use it, just as with wood.