2012 MES 40 vs. Old Model MES 40

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Thanks Todd, I have one coming and am excited to try it out.
 not sure what I am going to try first though. Maybe another pork roast, the last one tasted like the lit end of a cigar. I would like to redeem myself to the wife and kids
Hi Todd,

Any updates since your last batch of tests? I just ordered my AMNPS this morning and can't wait to try it out. Hopefully removing the water pan and pulling the chip loader out and turning 180 degrees will keep the pellets smoldering in my 2nd gen MES 40. I've done the stove pipe mod also so hopefully that increases the draft inside the smoker as well. If you have any other updates, let us know!

Thanks again Todd.
Hi Todd - I just joined this forum & am brand new to the world of smoking meats. Bought my 1st Masterbuilt 40 (new generation) at SAMs last week. I wish I had read your review before purchasing it but it sounds like you have come up with some fixes. Could you summarize those fixes or would you recommend returning the unit? Also I live in Illinois & we have regularly been below 0 degrees. I have put off seasoning my new smoker until it gets a little warmer. Is this necessary?
Hi Todd - I just joined this forum & am brand new to the world of smoking meats. Bought my 1st Masterbuilt 40 (new generation) at SAMs last week. I wish I had read your review before purchasing it but it sounds like you have come up with some fixes. Could you summarize those fixes or would you recommend returning the unit? Also I live in Illinois & we have regularly been below 0 degrees. I have put off seasoning my new smoker until it gets a little warmer. Is this necessary?
No Need To Return your new smoker

Every smoker has a learning curve, and the MES is no different.

I just smoked some trout, salmon, and even cheese, and the outside temp was right around 0°

Fire it up and season your smoker

Keep an eye on the temp, and make sure the controller maintains a correct temp inside

There will definitely be a burned plastic smell, so you'll need to "Mask" the smell with some chips burned in the chip pan

Keep Us Posted!!!


Though I don't have a MES,  I have found this thread very useful while I try to help MES owners incorporating their AMNPS.    Still waiting for someone who's frustrated with their smoker to send it to me, so I have something to fabricate.
A week or so ago I purchased the A-Maze-N Pellet 5x8 smoker from your company. I will be using it in a recently purchased MES 40 new generation.  I have read some horror stories in the forum. Some of the stories concerned difficulty getting the pellet smoker to remain lit in the MES 40 new generation. Any advice you can give me as how to avoid this problem would be appreciated.

[if !supportLists]1)    [endif]Where should I place the 5x8 in my smoker?

[if !supportLists]2)    [endif]Should I pull the wood chip loader tube completely out of the smoker?

You may be able to help with these issues as well.

[if !supportLists]1)    [endif]I hung a CDN DTP482 digital meat thermometer probe on the middle rack of my new MES 40 and it consistently read 25 degrees higher than the temperature on the MES 40 display. Should I be concerned or just adjust the temp accordingly?

[if !supportLists]2)    [endif]I was surprised at how much the temperature fluctuated.  I set the temperature to 200’ on the MES display (225’ on the DTP482).  Once the temp reached 200’ on the display, the heating element shut down but the temp continued to climb to 215.  Then the temp would start to drop, when it reached 200’ on the MES display (225’ on the DTP482) the heating element kicked on but the temp continued to fall until it reached 185’  Should this be a concern?

Any help you can give me is greatly appreciated!
I just got my new MES 40 over the weekend and tried it out.  Same issues Todd and others have described regarding the actual temperature being way off from what the unit's thermostat reads.  In my case, it's about 40 degrees difference.

I called Masterbuilt this morning and they said that it is because the thermostat measures the temperature of the body (it's built into the back wall) and my probes are measuring the air temperature.  Before they replace anything, they told me to put a probe up against the back wall right by the thermostat and see how well it matches.

My main question, which the rep didn't have an answer to, is what use is a thermostat that measures the wall temperature rather than the air temperature?  Since the meat isn't cooking up against the wall, it's cooking in the air on the grates, knowing the wall temp is useless unless it matches the air temp, which it clearly doesn't in this case.  She didn't have an answer, but it sounds like this unit is just designed in such a way that you are required to use a separate temperature probe to know what temperature you're actually cooking at.

Anybody else actually put a probe up against the thermostat to measure the temp?  I'll be running that test tonight.
If your temps in your MES are higher than what MES display say's ,don't worry about it .Sounds like you know how much of difference so just adjust temp setting according to difference . Watch where you are putting your probe . Try putting it on left side just under draft control and about midway down wall . see what your temps are . You might see a difference if you were reading temps by back wall center. Also get yourself a Masterbuilt electric Cold smoker kit . $59 bass pro . Works great . Don't have to worry about it staying lit .
Another new bs story from the reps. Too bad meat is cooked by air temp and not by wall temp. As for adjusting temps...what happens if hes reading 40 under and has it set at say...250? That means the highest temp he can smoke at is 235 true temp. How about if mb just fixes these things someday?
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What I was saying was that  when putting the Maverick probe by the back wall where the MES sensor is  maverick reads 330 degrees when MES was set to 275.

When I put Maverick probe on left side of MES about mid point in the box Maverick reads approximately within 5 degrees of MES display .And yes Maverick was calibrated more than once with boiling water . Granted if your MES is running 40 degrees low send it back . Even before I found out about the dramatic differences of temps in the box I did not care about temperature because I knew it could be corrected by where I set temps . When I spoke to Masterbuilt I told them how I placed Maverick by back wall near their probe and even at that they still sent me a new controller .After installing new controller nothing changed until I moved Maverick away from MES probe .Don't know reason and don't care,all I know is that food cooks how it is supposed to and coupled with the Masterbuilt Cold smoker attachment it does an a%% kicking job for an electric . It is my go to smoker when I want something quick ,or need to cold smoke. Otherwise it is my Kamado  that does the heavy work . Partial to charcoal but love the MES too.I don't bother with the offset anymore. Bought MES 30 from Lowes (Masterforge branded version) for $161.00 with veterans discount. Masterbuilt Electric Cold smoker attachment for $59.00 Bas pro. For that kind of money can't complain .
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Thanks to everyone on this thread as well as the many threads on this topic. I purchased the 2nd generation MES 30 from LOWES about 3 weeks ago. Fired it up and of course not getting the smoke we all need for great food using the wood chips in this smoker. After hours of reading on this site I made the jump and purchased the AMPS from Todd's site and smoked my 1st brisket on Saturday. I had almost 13 hours of PERFECT smoke (all thanks to everyones hours of suggestions and tips to modify these smokers to the way they should work out of the box). My set up as follows: 3 inch elbow on the side damper (just fits snug right on the smoker with no modifications), the chip shoot about 1/4 out with the dump slot upside down, chip tray removed from the smoker and the water/drip pan sitting on the bottom directly below where it would normally sit. The AMPS sits above the hole for the water pan on the heat shield and a piece of foil the same size as the AMPS on the rack above it to sheild drippings. I followed Todd's lighting instructions to the T and had absolutly perfect smoke from 5am to 6pm Saturday evening. I did have to torch it mult times during the 1st 10min lighting process to keep a small flame going but I think that was because it was very humid outside. I had to remove the 1st rack at the bottom, there just isn't enough room in the MES 30 between the heatshield and the 1st rack. I still had plenty of room for a 10Ib brisket and a mess load of sausage to feed 8 adults and 6 kiddos and I still some brisket left to eat yesterday. Thanks again Todd on a absolute great product. I was selling the crap out of it Saturday evening so you should have 3 more guys ordering their AMPS very soon. Thanks everyone and happy smoking!!!!
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thanks for info I just took nine back as  after 2 times of use it would shut down after 30 min So gonna try one  more but can't find another 40" one without window. I am still looking!
Observations from a geek:

Test conditions:

MES 40 "windowless" second generation, model 20070613 available at Lowes for about $279.00 before discounts.

The unit has already been "smoked in" and used about 4 times since new.

Test temperature the unit is set for is 225 F.

Outside temperature is 78 F (early Arizona morning with cloud coverage).

It has the smaller chip tray, and chip loader from the factory.

No chips in tray, heating element only.

No liquids in water tray, wanting to see the unit's inherent temperature characteristics without other "stabilizing" factors (such as water or large hunks of meat).

Chip tray and loader fully inserted.

The "second probe" mention below is actually the built in meat probe, plus a chefmate remote probe both near the middle of the unit, set slightly left of center.

Both probes have been boil calibrated, and read within 2 degrees during calibration and this test event (once you allow for variations in display refresh rates).

The "button" sensor, which is read by the circuit board to determine when the heating unit is switched on and off is:

1. located on the same side, and near the heating element.

2. is bolted to the rear bulkhead.


1a. on all heating cycles (except the initial heating cycle), it gets up to your set temperature faster than a second probe which is set on one of the middle racks.  This results the heating element switching off before the second mid-rack probe reaching the "set temperature" by about 6 degrees.

2a. on the initial heating cycle, the thermal mass of the back bulkhead actually lowers the "button" sensor by several degrees (relative to the second probe), which causes an initial overshoot of temperature.  I experienced about a 30 degree initial overshoot of internal temperature due to this characteristic. 


Initial heat cycle, second probe temperatures hit 255, before the button probe registered 225 and switch off the heating element.

Temperature dipped to 189-192 on the second probe, before the temperature dipped below 225 on the button probe (bulkhead thermal mass), and switched on the heating element.

On subsequent cycles, the button sensor hit 225 (and switched off the heating element) when the second probes were at 216; with the element "off" it was still radiating heat and the second probes eventually reached 219. Statistical "average" second probe temperature observed, after two hours, was 205.5 degrees (against a set point of 225).


On the initial heating cycle, second probe temperature phase leads button probe significantly (due to bulkhead thermal mass, which is conducted into the button sensor).

On subsequent cycles, the proximity of the button probe to the heating element, and the heated bulkhead causes the temperature phase to lead the second probes "slightly".

Suggested engineering change:

Move the button sensor up about 10 inches (and center it from left to right), provide better thermal insulations from the bulkhead, so it reads actual free-air temperature more accurately.

Devil's advocate:

Exaggerated temperature swings encourage the heating element to stay on longer, which helps increase the peak temperature seen by the chip holder.  This encourages more complete combustion of the chips.  The large swings also allow for the chips to start smoking at a lower "set" temperature.  The large temperature swings may very well be an intentional design feature.

For those who are using products like the AMNPS, the large swings are not a benefit.  The typical swing temperature seen, after the unit had been running over 2 hours, was roughly 27 to 30 degrees.  In the grand scheme of things, not bad, but not great. Adding meat and water will improve the stability, but the high to low swing range will likely remain similar, as will the average cabinet free air temperature. More data is needed with a loaded cabinet to be sure.
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Testing Sub note:

After four hours of testing, the MES's meat probe started reading 20 degrees higher than actual.  Could be a bad crimp in the probe. 

Opening the front door for ten seconds (dropped chefmate second probe temperature to 170), only caused a 3 degree overshoot (228 vs. 225 set temperature), upon recovery; quite good.
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Hey y'all, new to the board and first time posting. Just got the MES 40 model 20070512 and just finished the seasoning. I've read about the temp differance using an independent thermometer from the MES so I was prepared and ready to take note. I did have the expected temp differance but opposite from what I've been reading about!

Set temp 275*
MES highest temp was 271*
Meat probe constantly read constantly 250-259*
Digaital thermometer read between 235-255*

So a concerned with the "actual" temp never reaching set temp which seems to be the opposet issue to others. Can any give advice or help diagnose the issue?

Sounds like you already diagnosed it.  Sometimes its higher, sometimes its lower.  You have the one where the controller reads 25 to 40 degrees higher than actual temp.  The problem with that one is that you cannot smoke at temps higher than about 250 as when you set to the max setting of 275 you will only be able to reach about 250.  I'm going to announce this now....... anyone thinking of buying the masterbuilt mes units be advised that the generation 2.5 (yes 2.5...I have no idea why Masterbuilt is not calling it gen 3) is just now coming out.  They've gone back to the larger vent on the top, gone back to the full size oval water pan / drip tray.  improved smoke box and other refinements.  Hopefully the biggest issue about the controller has been addressed also, but it has a new look and has.....tada.... bluetooth.  And the sportsmans model has 6, yes six, racks.  Anyone considering the masterbuilt should look into this model as it looks like it may have some of the bugs of the gen 2 worked out.
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Thanks for the reply! Any idea if replacing the controller will help correct the problem? Or at least get the smoker hotter for when I want to smoke chicken?
Thats what they did with mine..... 3 times.  Never got it to get any better.  Did you read what I just posted?  The new model is out. Why would you keep a new unit that is giving you problems?  It not like MB isn't aware of this issue.

BTW....heres what I finally did to mine.  Got an Auber PID controller and married the MES to my Traeger.
In other words, the cabinet was the only thing I found useful.
Not good news for me then! I have seen the newest model on MB site however this one is an early Christmas present from my wife so we all know how that goes! :)

Very creative on your part but pretty sad to pay that much money just for a box.
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