I closed the damper today as far as the slide would let me. Seems like theres still a lot of airway open though. This did nothing to change the flame at all. Still smacking the roof of the stove. The control panel temperature gauge is what I was talking about. As for piping I have it straight run out the back (about a foot from the wall) then outside about 3 ft up from the T. I clean the outside once a week. Only been running it about a month now so it's never that dirty. I left a message with them today, no call back thoughBy thermostat, you mean a remote one mounted on a wall, or the control panel temp reading?
Almost sounds like you have no stove fans operating or something. How much exhaust chimney is connected and is it clean?