I'm trying to address a smokey odor in basement, likely smoke coming down oil burner flue, since oil burner is not used hardly at all anymore. There is a low flow radon fan in the basement, and an insert on the first floor. I opened the basement window a little this morning, and there was a big flow of air coming in. I left it open a crack and will see how that works out by when I get home in the evening. When the stove on the first floor gets totally cold, there is some cool air coming down the chimney, but a little burning newspaper gets the draft flowing in the right direction and there is no problem with smoke. The house is about 7 years old now, and an energy audit this past summer with a blower door test showed that it was quite tight. I've read about the stack effect, make up air, etc, but still wonder where all that air is going to. Perhaps I will see if air is escaping through the bathroom fan dampers upstairs, maybe block them off temporarily. I've sealed the ceiling penetrations on the second floor the best I can, but I can revisit them as well. Is negative pressure in the basement a normal thing? If the open basement window works, should I just put in a cheap air supply vent, like the Condar ASV-90, http://www.condar.com/asv.html ? In the basement? On the first floor? Both? For other background, the oil chimney terminates several feet ABOVE the wood chimney, which is SL300 interlocking galavnized pipe in a chase. It'd be hard to extend the wood flue and/or shorten the oil flue. Prevailing winds tend to blow smoke in direction of oil chimney. I've been told that the reason oil chimeny was higher was because the oil smoke would eat up the other chimney. I don't think there is an outside air kit available for my Hampton, but would consider an asv there. I'd like to spend a little more time down in the basement and the smokey odor could be annoying. Punching holes in the wall to let the cold air in just grates me the wrong way. Thanks for reading.