Got a question about a St.Croix pellet stove I was called out to service. I have not seen many pellet stoves here in southwestern Missouri, Springfield to be exact, So I dont sevice many or know much about the installation requirements of them. This one didnt seem right because the glass was all sooted up and the owner said he only burned 50 lbs in it. It's a 3" exaust with two 90's going into an existing interior flue with a 6" thimble but the flue tiles are 13x13. The flue is 20' tall with no obstructions around it, and drafts great when a wood stove was there prior to the pellet stove installation. Can someone please tell me if this stove needs to have a 3" liner to sufficiently work properly. Thanks.