I just bought a pellet stove and am unsure which position the impingement plate should be -- flat towards the back or forward towards the door. I have an Englander Summer Heat 25-PDVC which I bought at Lowe's. The person who sold the unit to me at Lowe's had no idea. Whichever position the plate is in, what does it do? Will I get more or less heat with it forward or back? Many thanks again! *the impingement plate sits above the burn pot.