I have a Whitfield Pellet stove about 20 years old. We have had it serviced a few times. The last time was in December 2009, but it's still not working properly. When I start it up, I always have to have the heat output switch set to the highest position to make sure there's enough air flow. Once the fire is going for a while, I can't turn the switch to a lower position because the flame turns orange (not a bright yellow) & eventually goes out. I've had the house fill with smoke also.