danson v50 draft setting

[jbc149]

Hello everyone new to this site looks like a wealth of info. I have a Dansons Vulcan v50 pellet stove it seems to burn better some days then others .On the low setting it burns the pellets up too fast and on the high setting it piles em up. Yet other days it works fine I have tried the trim pot adjustments feed and combustion fan.I just can't get that happy medium .I got 3" pipe 8 foot with 2 90 degree bends no outside make up air connection. Here are my questions :1 could I be depleting the air in the space it's in a finished basement 12x 20 x 8 with an open staircase no door to the first floor ??? 2 what draft reading in inches of WC do they recommend ???Dansons had no idea even though it appears to have a place to test for it on the front of the firebox????I also tried different brands of pellets .I have also opened the basement windows with no noticeable difference in the flame . Combustion fan amp draw is per specs .Thanks Jim