Just installed a 25-PUF and the specs are as follows. Vented 3inch pipe out the back 24 or so inches to clean out tee then up 4 feet. Burning New England Pellets (Schuyler Plant) and the "3 buttons" on the bottom are 1-9-1. On 2-3 (Blower speed same as feed rate) the pellets do not fully burn and the burn pot fills up but maintains weak flame and throws little heat, so much not so that the Room blower shuts off. Glass is BLACK on the side but not in the center. I turned it to 5-5 and it seems to be burning well. I was burning the Same pellet in my 25-pvdp and burned like a champ. As far as cleaned did it yesterday before the install. OAK not hooked up. Thanks for any help.