When I first moved in here in '03, the insurance company sent me a drawing (along with the pile of paper you get when you first open a policy) showing a wood stove & and oil burner in THE SAME FLUE. It said right on the paper that the wood stove had to be BELOW the oil flue - why, I have no idea. 2 years later when I decided to go with coal, all of a sudden they did a complete 180° - the lady just about jumped through the phone for me mentioning it! " WOOAH! YOU CAN'T DO THAT
So, WTF changed in 2 years?
So with that, instead of spending $2k on a new chimney (that's the LOW end out here), I just used the hole that was already in the chimney for the coal stove. Been burning 8 years now, without ONCE EVER hearing my CO detector. Yeah, it works - brought it out in the barn & within 30 seconds of starting my motorcycle, it was screaming.
I just changed the battery today - date I always write on them said January '10 - not bad!