I need help with my mailbox mod please... will not stay lit.

Discussion in 'Electric Smokers' started by haeffnkr, Mar 25, 2017.

  1. haeffnkr

    haeffnkr Fire Starter

    I have a Master Built bluetooth 40" smoker from SAMS, the 2.5 generation model.

    I have a mailbox with a 3 foot dryer house that is 3" diameter with 3 one is holes in the mailbox lid.

    I am using LumberJack pellets.

    I have never gotten more than an 90 minutes of smoke out of this setup.

    I have put the mailbox facing into the wind.  I have put a fan in front of the mail box.  I have microwaved the pellets. 3 times at 1 minute each time.

    I used it yesterday and was smoking sausage. I just had to keep putting pellets on the embers every 30 minutes.  Wind was blowing into the mailbox and straight shot into the smoker with the vent wide open. I usually have a piece of pvc pipe, 4" and 6 inches tall to act as a stack to get even more draft.  I have put the amps on a brick to ensure the draft is at the bottom.

    I am out of options. This setup was supposed to be set it and forget it.  I have used this setup 10 times now and it has never been set it and forget it. 

    I dont know if the draft is too strong and it blows out the fire or the draft it not enough to keep it going.   But again... when I put a small fan on the front of the mailbox it still fails.

    Any ideas?

    thanks Kevin
  2. johnmeyer

    johnmeyer Smoking Fanatic

    Random thoughts.

    The brick won't increase the clearance between the bottom of the embers and the flat surface. I think you will get better results with "stilts." Just use four small 1" screws (or longer) that you bolt near each of the four corners of the AMNPS. Then, ditch the brick. With thin enough screws you don't even have to drill out the holes. Just use machine screws and a nut.

    A picture of your setup would help.

    The inlet air holes in the mailbox should be below, not above, the pellets.

    Make sure the mailbox is below, not above, the chip loader hole that you are using for the intake.

    This is how I did mine. The four air holes are drilled near the bottom of the can. You can see them in the second picture, if you look closely. My AMNPS actually sits halfway up in the can, higher up than I wanted, but it sure stays lit easily. I had a few problems keeping it lit in the year that I used it inside my MES-30, but have had no problems since I started using it in this mod.

    This mod changes everything for me: the smoke tastes much better; I can spend hours doing other things during long smokes; and I can cold-smoke. I can clean the MES long before the AMNPS cools down.

    No downsides.

  3. I think johnmeyer has you straight on this, Give it a shot and get back with us, We'll get you going one way or another.
  4. mr t 59874

    mr t 59874 Master of the Pit SMF Premier Member

    This should help you.

    • [​IMG]
    • Mr T 59874
    • 11th Commandment, "Thou shalt not say, I've nothing else to smoke"
    • [​IMG]

    After receiving a tray type, smoke generator it was soon discovered that by placing it on top of a small colander, it burned much better.

    For convenience, I placed small bolts in each corner to replicate the colander. This solved all of the burning problems.

    Knowing DaveOmak was having problems with his unit, I informed him of my solutions. He then modified his which seemed to solve his problems as well.

    If you modify yours, let us know how it worked.

  5. haeffnkr

    haeffnkr Fire Starter


    Thanks for the tips so far.  Adding the legs seems like a great idea.

    What do you all do for pellet prep? nothing or microwave for x minutes?

    Wind?  -- sometimes I have gusty wind..  you all have no issues with gusty wind blowing out pellets? back drafts cause issues? 

    You worry about the wind? set the mail box so the wind blows into it?

    Picks of my setup below...

    From a couple of months ago.... I had a heck of a time with these sausages... I wanted to cold smoke these for 6-7 hours... it took 3 days cause the pellets kept going out with a fan blowing on them and whatever I tried... I was very frustrated.

  6. mr t 59874

    mr t 59874 Master of the Pit SMF Premier Member

    Tanks for the pictures, they help tremendously. First what is the purpose of the hole at the top of the MB, we want draft to enter the bottom not the top, consider closing it. Picture you firebox as a wood stove. Have you ever seen a wood stove with the air inlet at the top of the door?

    You shouldn't have to prep your pellets. If you have an efficient   setup it will not be needed.

    On windy days, think what could be done with what you have to block it, example, place it in a large box or something to block the wind.

    Hope this helps,

  7. cmayna

    cmayna Master of the Pit OTBS Member SMF Premier Member

    Yes for putting legs on the pellet cage as what Mr. T shows.  I also put legs on my mailbox to elevate it off the ground for air circulation.  Put some holes in the bottom of the mailbox as well as the door itself.
  8. haeffnkr

    haeffnkr Fire Starter


    I got the idea for the top hole in the mailbox from one of the locals here - http://www.smokingmeatforums.com/t/247202/mes-mailbox-mod#post_1569401  

    I thought it helped keep a steady draft through the box was the intent.

    Makes sense to close it. No I never seen a wood stove with a draft opening in the top of the fire box :) 

    What does a vent stack do for the pellet burn and the overall draft of the setup? 

    thanks haeffnkr
  9. mr t 59874

    mr t 59874 Master of the Pit SMF Premier Member

    Don;t worry, you will have plenty of smoke movement. Too much air movement decreases the efficiency of the MB.

    The length of the stack will determine the amount of draft through the MB.

  10. haeffnkr

    haeffnkr Fire Starter

    Live Update.....

    Mods made - 

    Added 2.5" bolts to rise up the amps

    Closed upper hole

    Sealed up the 3" pipe a bit with metal foil tape to eliminate any unwanted drafts.

    Microwaved pellets - added 2 rows ( I have NEVER been able to get 2 rows to burn end to end ) 

    Torched and let burn for about 10 minutes

    Set the tray in the middle of the mailbox ( I always had it right next to the door before)  This way the draft should have to go through through middle of the amps and out the back of the mailbox and into the 3" pipe. 

    12:19 CDT I took the pics set the MES to 225

    I will update in a bit... thanks for the help.

  11. mr t 59874

    mr t 59874 Master of the Pit SMF Premier Member

    Will look for your post in about 6 hours.  [​IMG]

  12. dward51

    dward51 Master of the Pit OTBS Member

    I would drill a 3rd hole in the bottom row and then use magnetic fridge stickers to partially close them off if needed.  Like you found, that hole up top was venting air away from the pellets into the smoker and you had poor draw across the pellets.  The air flow needs to be at or below the level of the pellet tray for best performance.  Looks like you are on the way to getting this solved.
  13. I notice you were cold smoking the sausage. If the temp in the smoker isn't a few degrees higher than the ambient temp you won't get any draw and will produce a backdraft causing the pellets to go out. If you notice smoke coming out of the mailbox itself it's lack of draw. You can turn on the mes for a minute occasionally to get the smoke drawing. I also added the legs and it definitely helps. On days that I want heavier smoke I use the tube instead of the maze. Never had a problem keeping the tube lit.
  14. johnmeyer

    johnmeyer Smoking Fanatic

    In looking at the pic that I quoted above, it sure looks like you are not filling the tray all the way to the top. I have found that if I don't fill the tray almost to the top that I don't get enough "mass" ignited for the fire to self-sustain.

    As a "thought experiment," imagine filling the tray so only one layer of pellets is in one of the rows (i.e., pellets all the way across the width and length of a row, but only one pellet high). If you then lit those few pellets at one end and got them going, I think you'd find that there would not be enough pellets to generate sufficient heat to cause the adjacent pellets to catch so that the whole row would eventually burn. However, at some point, if you add enough pellets to have a row that is two pellets deep, then three pellets deep, and so on, you'd get to the point that it would self-sustain because you'd have a big hunk of pellets on fire, and that would provide enough heat to cause the adjacent pellets to "catch."

    So, don't try to skimp on pellets. They don't cost much compared to the food you are smoking, and Todd will enjoy the extra business you'll give him if you add chips until the AMNPS is filled to the top.

    I have seen a few people report that if you fill it all the way to the top so that the pellets are literally falling out the sides, that one lit row can "jump" over to the adjacent unlit row. I actually did have this happen once, but I think I may actually have had a "bridge" (i.e., I was careless and let some chips lie across the divider between rows).

    If you do end up with two rows burning at once, that is not even close to being as bad as having the thing go out, especially since the leap to the adjacent row probably won't happen right away, if it ever does. The worst that would happens is that you would get a little too much smoke for awhile, and the thing would burn out sooner than expected. To avoid this happening, just do a quick check after an hour or so. Unlike having the AMNPS inside the MES where you lose a lot of temperature and smoke if you open the MES to check on whether the AMNPS is still burning, there is zero downside to opening the mod to check on whether everything is OK. You'll lose smoke for the ten seconds you have it open, but only the smoke contained in the tiny little mailbox, not all the smoke in the MES. In addition, there will be no impact on the temperature inside the MES.

    Try more pellets. I think that will make a big difference.
    Last edited: Mar 26, 2017
  15. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    haeffnkr, morning....  While watching my MB mod smoke some meat, I noticed when I opened the MB door, there was recirculating smoke behind the blank spot in the door....   Well, recirculating smoke is low on oxygen...   some folks at higher altitudes need all the oxygen they can get...   So, thinking an upper air inlet would help to sweep the "stale smoke and air" from the MB I put in an extra hole...   I think it also provides extra oxygen for some secondary combustion to burn particulates and tars...    You can google "wood stoves and secondary combustion" to see what's out there...

  16. smokeymose

    smokeymose Master of the Pit

    Pellets not staying lit is an airFLOW problem, which everyone agrees. You can have all the air in the world available on the inlet, but if it can't flow the coals don't get enough air. Is the outlet vent big enough? I don't think there's a problem with the pellets, although I did have a load of Todd's pellets go out once, but blamed it on humidity (It was raining). Never microwaved or anything. As long as the pellets are kept dry they shouldn't need any of that. I also wonder why everyone uses 3" pipe. Is that some rule I wasn't aware of?
    I don't have holes in the front. I drilled holes in the bottom and raise the box off the ground and have 4" pipe. I use a tube instead of a tray, but I doubt if that makes a difference. Anyway, look at the whole flow, not just intake.
    (A long ago HVAC tech.)
  17. haeffnkr

    haeffnkr Fire Starter

    4:00 pm CDT update.

    Going Slow.... but not out.  Drill another hole in the mailbox for more draft?

    It should be out past the turn by now right?

    The smoke coming out of the MES is super sweet..... Hickory :)

    thanks haeffnkr

  18. mr t 59874

    mr t 59874 Master of the Pit SMF Premier Member

    I agree with johnmeyer that adding more pellets would help. If you feel you are not getting enough draft, increase the difference between the air inlet and the smoke exit from your product chamber. This can be done by adding a length of pipe to your chamber or others have used a fan to draw air from the exit.

    If you are one who wants secondary combustion, good. Don’t understand how one would get secondary combustion with smoldering smoke. Doesn’t combustion mean fire? Definitely something I do not want when cold smoking.

     As my temperature target, in the product chamber, when cold smoking is one or two degrees from ambient temperature, I want to cool the smoke, by allowing the firebox and subsequent tubing do both, clean and cool it.

     As long as smoke is moving, there is no need to worry about stale smoke, whatever that is. I live at 2400 ft., if more oxygen is needed to burn fuel, I want it introduced at the bottom of my fire, not from the top, which is one reason for raising my tray smoke generator to the height of or above the air inlet, as air coming in from the top was not working at all,  just my personal preference, I could be wrong.

  19. johnmeyer

    johnmeyer Smoking Fanatic

    If I am reading the times on your posts correctly, the answer is "yes." With Todd's pellets, they should take about three hours to burn one row. I've sometimes had a row burn in 2-1/2 hours, but never much less, and never more than about 3-1/4 hours.
    I don't know enough about the chemistry of burning to give a definitive answer, but the little knowledge I have of internal combustion engine pollution controls did make me think of this:

    Air Injection

    From that article: "This system was used to inject air into the engine's exhaust ports to provide oxygen so unburned and partially burned hydrocarbons in the exhaust would finish burning."

    Obviously the temperatures in an engine are far higher and the amount of air and fuel moving through the exhaust is many orders of magnitude larger, but despite these things, perhaps the same idea still applies.
  20. mr t 59874

    mr t 59874 Master of the Pit SMF Premier Member

    Burn time depends on the type of fuel being burned, along with the amount of heat and air supplied. There should be no problem achieving a 15 or more hour burn using a powder not dust for fuel using a 5x8 tray.

    No need to overthink a simple process.


Share This Page