Greetings Hearth.com members! After many years of procrastination, I recently took the plunge and purchased an experienced Accentra insert - circa 2004 but (supposedly) only having seen around 10 tons. I am now trying to figure out how best to install the venting and I had a couple questions that I can't seem to find answers to from other threads. Any insight you folks can provide would be greatly appreciated. First, outside air. I'd like to use outside air but not sure I can. I have a two story chimney, approximately 23 feet from the combustion fan to the top of the chimney, with a standard sized clay liner. I also have a ash dump with an external clean-out door. The stove will sit on top of the ash dump, so there is no way to install a pipe through it to feed the air intake. I was thinking that I might be able to install a PVC snorkel-type attachment through a sheet metal plate on the external clean-out door to allow the stove to draw air in through the ash dump hole in the bottom of the fireplace floor. My concerns about this method are: 1) the circulation fan, being on the bottom of the stove, would pull cold air from the ash dump opening and reduce the heat output of the stove; 2) the stove would pull inside air around the surround since it doesn't seal tightly; and 3) when not in use the open ash dump would allow cold air to be blown into the room even if I use a snorkel with an upside down "U" shaped trap on top. The other OAK option would be to install a full exhaust liner through a block-off plate to the top of the chimney and another 3-inch OAK pipe through the block-off plate halfway up the existing chimney, and connect a PVC pipe down the side of the chimney a foot or two and connect it to a hole in the top plate to allow outside air into the chimney. This is venting option #1 in the operating manual.I've read posts here from folks who did that but had bad results in terms of the flame quality after installation. Any thoughts on doing this method with a 23 foot chimney? Lastly, if I do not do the OAK at all, or leave the ash dump open, my preference (because I am frugal - not cheap - frugal would be to run a 5 foot flex pipe through a block-off plate into the existing chimney. My chimney (three flues - one for the oil-fired boiler, one for a fireplace in the basement and the center flue for the first floor fireplace where the Accentra will go) is currently capped. This is venting option #3 in the operating manual. Anyone have any thoughts on potential problems or draft issues with this method? Thanks in advance for your insights.