I recently got a Gen1 MES30, and an AMNPS 5x8 pellet tray. Both are good so far, but I'm having some trouble keeping the AMNPS going. I apologize for the length of this post, but wanted to provide some details.
Twice the AMNPS has gone out after 4-6 hours, with it sitting in the smoker, to the left of the heater. I've had foil above it at the water pan, so nothing can drip on the pellets. No water in the pan, chip loader tube pulled out some, and one time I removed the chip tray entirely. I typically run the top vent fully-open.
I'm using Lumber Jack pellets, their mix of Maple, Hickory, and Cherry, all together. I'm storing them in a sealed container, with a desiccant packet inside, to keep them dry (hygrometer shows 25-30% humidity in the container).
I assumed that poor airflow within the smoker was part of why the pellets went out after a while. I just finished my "mailbox mod", but using a toolbox. I raised the AMNPS up off the floor of the box, so air can get under it. The smoker is on Masterbuilt's stand, I'm using 3" flexible ducting to the toolbox, which is on the ground. I made (5) 9/16"-diameter holes at one end of the toolbox, for airflow. I have to think that's a reasonable amount of air supply. The air should flow across the tray, to the exhaust duct, located at the top other end of the toolbox.
But even with that, I couldn't keep the AMNPS going this weekend, running at 180F. And I've tried some more this week, with similar results. I sealed up some of the gaps on the toolbox, to try and force all the air through my vent holes, so it flows across the tray. I get what seems like a good amount of air coming out the top of the smoker, but the pellets keep going out after a while.
The last 2 nights I used leftover pellets, which were still sitting in the toolbox from the night before, so they weren't dried. I will try again with fresh, dried pellets.
But am I missing something? Even with controlled airflow, and trying to direct it over the tray, I'm still having trouble. Do I need even more vent holes? I saw a post with the popcorn tin method, it didn't seem like airflow was a problem for him, and I think 4 holes were mentioned, though I don't recall that a size was specified.
I wonder if perhaps my pellets are tougher to keep lit, maybe due to the Cherry wood in their mix? For an easy-to-compare test, if I just left the AMNPS outside, on the ground, should it continue smoldering for hours like that? That's a way to take the toolbox, etc, out of the discussion. If mine kept going out like that, for instance, then maybe my pellets are making things tougher. I do have some A-Maze-N Competition Blend pellets that came with the AMNPS, they're the only other pellets I have available, for comparison.