What would cause AMNPS to burn entirely in 3 hours?

[daveomak]

mail box mod.???

I would....

 

[Bearcarver]

Yes, it could be too close to the heating element.
I would put it on the rack above where you had it---Where the Foil protector is in the Pic.

Also if you fill the AMNPS too full, it could jump rows & burn up quick. Notice how the higher up the interior walls you go, the closer the rows are to each other.

Also if you put foil too close above the AMNPS, it can hold heat enough to cause it to get too hot.

Bear

 

[johnmeyer]

I would have said the same thing as Bear, but the picture you posted shows your tray filled pretty low, so it would be tough for it to jump rows. My experience, using the AMNPS both inside my MES and in my external smoking mod, is that the following things influence the speed of the burn:

1. The type of wood in the chip. I tried to find out something about your brand of pellets, but couldn't get anything useful. If this has happened before, then I'd try a different brand. The obvious thing to do would be to buy a small bag of alder directly from Todd, in order to eliminate this as a possible cause.

2. Too much air or too much heat. Fire (or smoke) requires fuel, air, and heat. Others have speculated that you might be getting too much heat from the proximity to the heating element. You can easily test that by moving the AMNPS up one rack, or putting an insulator under the AMNPS (you may need to elevate it a little if your insulator doesn't permit airflow into the underside). As for air, you say you only have a few holes providing air to the smoker, but if the door gasket is loose, you might be getting air from a small gap in the door. I couldn't tell what brand of smoker you are using, but on my MES, the latch has a tightness adjustment, and from the factory, mine was too loose and I had to tighten it.

3. Packing density. This is mostly a function of the chip size and length. I posted earlier this year about having the opposite experience to yours, where my AMNPS kept going out, after never having gone out for several years. This happened because I used the chips from the bottom of a large bag that were full of dust from all the other pellets. What I found is that if you combine dust and chips, that ends up plugging up the air between the chips and you don't get enough air into the mixture to sustain combustion. Your picture looks just the opposite, where the long length of your chips leaves a lot of air between them. So, my last suggestion would be to fill the AMNPS a little closer to the top; shake it a bit; and then press down a little (don't get carried away) to try to reduce the gaps between the chips.