Question: 1. I could not vent ventless gas logs. 2. That if I was to vent a gas log set using a L type vent i.e. venting up a short ways then horizontally out a wall (he called it direct vent), then I would need a glass front. He did not give me satisfactory answers as to why concerning the above two items except to talk about building codes, heat loss, etc. I don't care about those things. My son-in-law has ventless gas logs in his wood burning fireplace which he operates with the damper shut. I am going to have him open the damper slightly and see what effect it appears to have upon the gas log operation. I imagine it will not have any visual effect. The only thing that will happen is that a draft will be created that will cause house air to move out the damper opening. My wife says when she is in their house and those logs are burning with the damper shut she can feel the reduced oxygen supply in the house air after the gas logs have operated for a while. Also, what about providing an outside source of combustion air piped into the firebox? Answer: Unvented gas logs can be vented, but the kicker is that this venting must be into a regular fireplace. They have not been tested and/or approved with L vent or any other DIY scheme. The question is not whether it will work, but whether your insurance company will pay the claim if something goes wrong...or whether a danger exists in some cases. Your wife is correct..a lot of folks are sensitive to this. For this and other reasons, a direct vent (sealed) appliance will be more appropriate for many installation. But, yes, if you are installing the logs in a regular existing fireplace, you can surely open the damper. Of course, you are cutting way down on the efficiency at this point, and may want to consider a sealed (direct or B vent) gas insert instead.