after -->The previous owner of the house had the woodstove hooked up into the single chimney. Since it was already carrying two outputs (furnace and hot water heater) that was a bad idea. Since it was hooked up to the furnace, any creosote leaking down to the furnace would be an extra bad thing. We opted not to use the woodstove until we had a separate chimney for it. Now we do. It has a slight crook it it because it was otherwise a choice of moving the stove too close to the rug or cutting through the roof rafters. So a curve in the pipe was acceptable.