Here's what works for me with my P35i... When the stove is off, and the room is cool, say 60 degrees or so, I set the Igniter Switch to Automatic, the Feed rate knob to 3 and the temperature dial to 2 or 2.5 and turn the mode selector to Stove Temp at about 60% fan speed. I rarely turn the temperature dial beyond 2.5 and the highest I have ever had it in two years is 3. Typically, once the place starts to warm up I turn the temperature dial to 2. Keep in mind that I am using the numbers, not the degree settings on the temperature dial because I am in Stove Temp mode. When we go to bed I might turn it down to 1 or 1.5 to save pellets but keep the place fairly warm.
The only time I may adjust the Feed Rate knob is if I see excessive ash building/clumping up along the front lip of the burn pot, especially in the corners, after 4 or 5 hours of burning. When this happens I like to scrape off the accumulated ash before making any adjustments. To clear the ash off of the front of the burn pot I do the following: First I open the hopper door (this prevents the feed of pellets) for a minute or so to let the fire die down a bit (but not too much, you don't want it to go out), then I turn the convection blower down to minimum (to minimize the amount of smoke that may escape into the room), then I carefully and slowly open the door and quickly scrape the accumulated ash off of the first inch or so of the burn pot with my scraper tool. Then I slowly close the door, close the hopper lid to resume pellet feeding, and turn the convection blower back up to about 60%.
After clearing the ash then adjust your feed rate down slightly, no more than a half a number. Mine is usually on 3 so I might turn it down to 2.75 or so. Now with the freshly cleared front lip of the ash pot you will see how much less the ash accumulates.
Mine is usually happy at a feed rate of 3 and a temperature dial setting of anywhere from 1 to 2.5 or 3. The thread you mentioned above describing how your stove works (and other threads I have read, as well as the manual, say the feed rate should in most cases be somewhere between 3 and 4.
Basically you should not constantly adjust the feed rate knob. Once you find a setting that works with the pellets you are burning and the ash is not accumulating alot in the front of the burn pot, or hot burning pellets are spilling into the ash tray, then you really only need to make adjustments to the convection blower and temperature dial settings. I can easily get 16 to 18 hours out of a bag of pellets with these settings on a fairly cold night like tonight which is about 14 degrees.
For reference, my house was built in 2003, 2x6 construction, double pane windows, 2400 sq. ft., 2 floor, 8 room colonial. With my ceiling fan going in the living room where the stove is to circulate the air the living room is typically 72 or 73, the rest of the floor is around 68, and upstairs maintains 63 or 64 most nights.
The only time I use the Room Temp mode is when the weather is warmer during the shoulder months.
That's what works for me, hope that helps get you started.
