2 Questions. 1. Do you have to or should you clean your chimney for your pellet stove? I have a metal chimney that goes straight out through the roof. If so, how often? Do they build up ash or creosote or neither? 2. There is a saw dust catcher ( for lack of a better term) on the rear of a Harman XXV stove. You have to remove a plate to get to it. Its on the lower side of the feed shoot before the auger. How often should this be vacuumed out? I did mine once last season.