Purchased a new Quadra-Fire Mt. Vernon Pellet Stove in October. Using good quality pellets used by many in area with out complaint. Vented six feet up through wall, air intake 1 foot below exhaust. Clean weekly according to manufacturers instructions. Worked great for 2 months then noticed dark window quickly after cleaning. Then black soot on tv screens, window panes, walls etc... in house. Outside wall where exhaust is tons of black soot, at least 4 foot diameter around exhaust pipe. Black soot on/in exhaust pipe/screen. Tech came out, put new panel in, new fake wood (old model may have caused poor air intake??) Still have the problem. Scary with the soot in house. Please help, any advice and/or wisdom will help as we wait for tech to come out again. He is 250 miles away, left message and waiting for call back.