Question: Why can't you burn wood logs in a gas fireplace? Answer: If your "gas fireplace" is a masonry fireplace with a masonry flue, only gas has been piped in for an after-market gas log set then you can burn wood by disconnecting the log set. If your "gas fireplace" is a factory-built fireplace with a metal flue, and came from the factory with a gas log set & burner installed then you typically cannot because the whole system has been designed, safety listed, and manufactured for use with gas only. Burning wood will change clearances in terms of how it has been installed to combustible framing, and facing materials. Plus, the size of the flue may not be adequate to evacuate smoke & gases from the wood so there's a good chance of smoke spilling back into your home. If your "gas fireplace" is a factory-built fireplace with a metal flue, then perhaps it may have been a wood burning designed fireplace with a factory optional gas log set installed afterwards. Check the listing plate typically installed inside and on the upper portion of the firebox. Or, if there's a grill on the bottom that flips down, there may be a plate there. The plate will have model & serial numbers, manufacturer's name, etc. You can then research this and determine exactly what you have in order to explore your options.