Question: Is it okay to vent a direct-vent stove through an existing chimney using adapters and a 4" stainless steel vent-pipe down the center of the flue for exhaust? Our concerns have to do more with carbon-monoxide, not necessarily stove efficiency. We are thinking that direct-vent stoves, with sealed fireboxes, are safer than b-vented stoves. The gas stove would be in a basement family-room, not far from other natural-gas appliances. Answer: Yes, Mark, it is OK to vent a direct vent up through an existing masonry chimney. To do this correctly you must use the proper adapters, which are sold by Dura-Vent. The exact part #'s are usually detailed in the stove installation manual. You are correct in your thinking that a properly installed direct-vent unit is less likely to cause you draft-related problems.