I was having difficulty on hot smokes due to the proximity of my AMNPS to the burner, the pellets would burn up prematurely after only 4-5 hours. When doing cold smokes, I was getting to much temp rise using pellets which is not a good thing while cold smoking salmon. So I came up with a solution I call the Mail Box mod.
Since doing this MOD, my burn time has Tripled on Hot smokes. I am now getting over 14 hours of TBS smoke from a single tray of pellets. When doing Cold smokes I get absolutely no temp rise, since my smoke source is now separate from my smoke chamber. Total cost was just over $20.00 at my local Home Depot.