my stove is a harmen p68 installed with a oak about two years after in a major rain storm I noticed sparks and small flames jetting out of my outside pipe.I called my dealer to see if they knew why this was happening, footnote I clean my stove about every 35-45 bags, they were no help but did say that maybe my oak was sucking in moist air and making creosol ,so I disconnected my oak. Since then no problems,except my gas kitchen range has a orange flame instead of blue,I think because of my pellet stove sucking my homes inside air. What to do? re-instal my oak or not? when this happened I was burning pelletsale.com soft pellets this year I'm using energex.