Avoid Temp Swings in MES (By Bear)

Discussion in 'Electric Smokers' started by bearcarver, Jun 18, 2015.

  1. bearcarver

    bearcarver Smoking Guru OTBS Member

    Avoid Temp Swings in MES   (By Bear)

    How I avoid much of the annoying heat over-running (Temp Swings):

    A lot of MES owners complain about the wide cycling spreads they get for awhile at the beginning of a Smoke.

    The following method I use should work with all MES units, and probably any other electric smoker without a PID set-up.

    When you start an MES by preheating it to a set temp it will run all the way to that set temp before the heating element shuts off. This could take in the area of one half hour. Then the heat will continue to rise for a while. I call that “Coasting”. The longer the run either up or down, the farther it will Coast. 

    In other words, if you want your smoker to be at 230°, and you set it at 230°, it will shut off at 230°, but depending on things like Ambient Temp, Wind, etc, etc the heat in the smoker could Coast up to 240°, 250° or sometimes even more. Then once it stops Coasting, the temp will eventually begin to fall, and continue to fall until it hits one or two degrees below your temp setting, and then the element comes on. Then since it just had another relatively long run coming down from the over-run you just had above 230°, it will now continue to fall below the set point after the element comes on. It may fall down as low as 20° or more below your set point before the temp of the smoker begins to rise again.

    This over-running can continue for a good number of heating & cooling cycles, before it settles down to only over-running a few degrees above and below your set point.

    The best way I have found to avoid this annoying problem is as follows:

    If you want your smoker to be 230° inside, set your control at 215°. Then let it run & shut off at 215°. Then watch how far it Coasts above 215° before it stops & begins to fall. If it runs to 230° or above, change your setting to 230°. Now that it won’t be dropping a long way before reaching the set point, it also won’t over-run much below the set point after the heating element comes on. Then since it won’t be making a long run to get back up to 230°, it won’t over-run much above that 230° shut-off point. 

    This will cut way down on the Over-running above & below your set point in a much shorter time than it would without playing this little game.

    Also if on that first run up, it only Coasts to 225° instead of 230°, just slide your heat setting up to 223° or 224°, and catch it at 230° on the next cycle.

    Once you do this for a few smokes you’ll be able to fine tune it. I have it more fine tuned than the above, but it would take too long to explain it in type.

    Note: For those of us who live in the North, you will learn that the heating tends to over-run in the Upward direction more in the Summer than in the Winter, and it will Over-run more in the Downward direction in the Winter than in the Summer.

    I hope this helps some of those who don’t like seeing the big Temp Swings in their Electric Smokers.

  2. brickguy221

    brickguy221 Smoking Fanatic

    Great tips Bear. Thanks for posting that information. From my experience on my "now parked" 40" Gen 2, I am aware of the temp over runs and under runs, but never knew why or how they might be controlled. The "word on the street" is ... "Da Bear knows" [​IMG]

    Again, thanks Bear .... [​IMG]
  3. Great Information !!! I'll have to try That !!  Oh Wait I have an RF, darn.

    To me this looks like some very useful information and should help lots of folks  Well written and easy to understand "Even for an old stick burner like me".

    [​IMG][​IMG][​IMG][​IMG][​IMG]       [​IMG]

  4. Nice job Bear. Great useful info for a lot of folks.  Jted
  5. rabbithutch

    rabbithutch Master of the Pit OTBS Member SMF Premier Member

    Thumbs Up

    Thanks, Bear!

    I will definitely make use of that information.
  6. daricksta

    daricksta Master of the Pit OTBS Member

    Bear, you've very clearly explained what I recently learned from personal observation and you added some tips I hadn't thought about. Jted also provided me with similar insight into how the MES controller works. I gotta figure out how to mark or save your post for future reference. Great job as always, Bear.
  7. ostrichsak

    ostrichsak Meat Mopper

    Good post.  Have you experimented with adding items to the inside of the smoker to see how that affects the swings?  If one were to add a heat-retaining liquid or solid (sand?) to the drip pan in an effort to add more insulation it would take longer to preheat but the swings should be controlled further as it won't get as cold before it heats again in those first few fluctuations as you described.  Curious your (or anyone else who has first-hand knowledge) thoughts or results on testing that.  In my mind that should produce similar results with less hands-on effort to achieve it if it works.
  8. daricksta

    daricksta Master of the Pit OTBS Member

    Ostrichsak, you'll see some members here advise using the water pan as a heat sink by partially filling it with clean playground sand and foiling it over. I tried that a few times and saw no difference with temperature stability. Bear nailed exactly how the MES controller works. Thanks to Bear's advice, I just foil over the empty water pan. I use it as another drip pan and it also serves to protect the heating element housing from drips as well in my MES 30 Gen 1.
  9. ostrichsak

    ostrichsak Meat Mopper

    That's how mine is right now so I'll probably just leave it and try preheating to 215deg next time and then stepping up to the desired temp once that temp is holding more solid.  Makes perfect sense to me.
  10. chef jimmyj

    chef jimmyj Smoking Guru Staff Member Moderator Group Lead OTBS Member

    Yes, adding Sand, Bricks and such, holds the heat and assists the coil in recovering and maintaining the setpoint. The swing issue only exists for the first couple of hours. It is a load of Cold meat that causes the rapid cooling after the coil turns off. Once the IT of the meat reaches 140°F or so, 3-4 hours in, the swings are small...JJ
  11. ostrichsak

    ostrichsak Meat Mopper

    That's been my experience for the most part as well: once meat temps start to come up things tend to steady which is to be expected with forces at work.
  12. daricksta

    daricksta Master of the Pit OTBS Member

    I'd like to see more posts by you just so I can look at your profile photo! Some guys take out the water pan but Masterbuilt and the mentors here advise leaving it in since it also acts as a heat shield/deflector and such if it's left foiled over and empty.
    Last edited: Jun 18, 2015
  13. ostrichsak

    ostrichsak Meat Mopper

    I'm fortune to wake up to my avatar every morning for over a decade now. ;-)

    My first few smokes I left the pan bare but after cleaning it a couple of times I started lining it w/HD foil first. Sure helps w/clean-up.
  14. daricksta

    daricksta Master of the Pit OTBS Member

    I also foil the bottom drip pan. Over the last few smokes I noticed that the water pan caught almost all the drippings which didn't leave much for the drip pan to catch (or the grease tray in the outside rear). I used to foil over the top of the heating element housing and tent over the AMNPS but again, haven't had much problems with grease dripping onto them.

    I stole my avatar from my son after he showed it to me. He and I are huge "BB" fans as well as fans of the last Godzilla movie. The meme with Walter in the car and Godzilla replacing Hank is brilliant.
  15. bearcarver

    bearcarver Smoking Guru OTBS Member

    Note that my original post was during "Pre-heating"----No cold meat involved.
    Actually cold meat does make it worse, but my explanation above was with an empty Smoker. It still over-runs the set point by quite a bit if you don't do my "above" method of cure.

    Just the fact that it has to drop 20° to 30° on the way down before it hits the set point can cause it to lose another 20° before it starts to rise. (With an Empty Smoker)

    Putting sand or bricks in can help some, but not enough to make it worth the extra effort to heat it up at the start. IMHO

    And it is not just the warm meat that causes the swings to be small after 3-4 hours. It is also because you aren't making big changes in your setting at that time. If you made a 50° change later in the smoke, the swing would be a lot bigger even with 140° meat.

  16. bearcarver

    bearcarver Smoking Guru OTBS Member

    Like I told JJ, putting sand or bricks in can help, but IMO not enough to make it worth the extra heating it takes at the start, especially in the Winter in the North. It takes a lot of heat to warm up a pan full of ZERO Degree sand.

    My main point in my original post above is " It is the long runs that cause the big over-runs":

    The run from Zero to 230° causes a real big over-run.

    Then dropping from 250+° down to 228° causes another big over-run, like maybe 20°.

    Then running up again from 208° back up to 230° causes another one!!!

    Each time it over-runs it gets a little less, but it still take a lot of time.

    My method above cuts that problem way down!!!

  17. dr k

    dr k Master of the Pit

    With the gen 1 and the chip loader all the way in the only air intake is through the grease trap opening in the back.  When the MES is up and running and you put a flame from a lighter to the opening it sucks the flame out into the smoker.  That short elbow from the trap to the inside of the bottom drip pan sure makes this smoker breathe.  I've noticed more even heating just by putting foil over the right opening between the water pan and right rear corner.  I want to push heat toward the opposite corner where the door latch is so it can come back across the food then out the vent, keeping the heat from going up the back wall over the CC thermometer out the vent.  I'm going to make a template.  I'll cover the right half of the water pan with foil while it's in the smoker and make sure the foil butts up to the back wall and right side wall but is open on the door side a half an inch or however close the closest point is between the water pan and the door.  Then cut out what covers the water pan opening.  It'll be a start but may take some time to play with it before making it in a heavier gauge steel/aluminum I can wrap in foil. 

  18. bearcarver

    bearcarver Smoking Guru OTBS Member

    I thought about doing what you're talking about a few times, but then I figured if I replaced the water pan with a flat piece of metal, the drips that fell on it would run off & drip below it, so I decided to keep the water pan in my smoker where it belongs (to catch drips) & just add my deflector plate in the bottom right to push the heat over to the center & left before it rises through the smoker & out the top vent on the right.

  19. daricksta

    daricksta Master of the Pit OTBS Member

    In my now-famous first pork shoulder smoke, I wrote that I bumped up the temp to 250° to reach my target 200° more quickly. This was about 8 hours into the smoke (with another two hours to go). Now I had the ET-733 maximum smoker temp alarm set to 250° at that point and the alarm sounded when the temp hit 252° so I bumped the max temp alarm up to 260°. Here's the deal: once the smoker settled back (fairly quickly) at 250° it stayed there for the rest of the smoke. I was in awe.
  20. daricksta

    daricksta Master of the Pit OTBS Member

    Bear has a movable heat baffle he uses in his MES 40 to redirect heat from the right to the left side as needed. As for me, I track the interior temps with my ET-733 and the time that I used both probes when smoking pork ribs I saw the hot side transfer from the right to the left side in my MES 30 Gen 1 over 7 hours. I never thought about where the air intake is.

    I'd like to see you construct what you're describing because I can't picture it.

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