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MES Temperature swings?

post #1 of 25
Thread Starter 

Hey guys, I just got an MES a few weeks ago, and I'm seeing crazy temperature swings when measured with my igrill2.  I recognize that the masterbuilt ambient thermostat is off, but it also tends to lag actual temperatures quite a bit.  basically when set to 208 *(I was aiming for 225 internal temp as read by my igrill2 ambient probe).  I get swings from 205 to 240.

 

Are there any mods that can help alleviate this?

 

My best guess is that the thermostat is getting a bunch of heat soak from the interior walls of the cabinet thereby making it read low, and read slow.  Has anyone tried insulating the thermostat from the interior walls of the masterbuilt and had any success?

 

Thanks,

post #2 of 25

I can't help with your question, but I'm sure one of the MES guru's will be along soon to give you an answer.

 

In the meantime, would you swing by "Roll Call" & introduce yourself, so we can all welcome you to SMF!

 

Al

post #3 of 25

Hi "nPoc",

That's a pretty common problem with most MES units, and other electric smokers.

 

I wrote this (below) up awhile back to show how I dealt with that problem with my older Generation #1 MES 40.

 

My new Gen #2.5 has a much smaller cycling spread.

 

 

This should help:

http://www.smokingmeatforums.com/t/208552/avoid-temp-swings-in-mes-by-bear

 

 

Bear

post #4 of 25
Thread Starter 

Thanks Bear, that's pretty much what I'm seeing. 

 

This is my smoker, *(although I paid about half that price)

https://www.amazon.com/Masterbuilt-20072115-Bluetooth-Smart-Digital-Electric/dp/B00TJ1OZR0

 

When graphing the temps of the igrill against the masterbuilt.  I really think the masterbuilt is measuring the air temp + getting heat soak from the internal cabinet temperature.  I think that's part of the reason for the swings.  Basically it takes longer for the masterbuilt thermometer to register that it needs to kick on because it's absorbing heat from the internal walls.  When I get a chance I think I'm going to take apart the back thermometer and see if I can't insulate it a little better from the walls so I can get a better air temperature reading.  The other idea I had was to add a different ambient air thermo-probe that doesn't sit on the wall and connect that into the controller instead of the built in one.  

 

Fun fun.

post #5 of 25
Quote:
Originally Posted by nPoc View Post
 

Thanks Bear, that's pretty much what I'm seeing. 

 

This is my smoker, *(although I paid about half that price)

https://www.amazon.com/Masterbuilt-20072115-Bluetooth-Smart-Digital-Electric/dp/B00TJ1OZR0

 

When graphing the temps of the igrill against the masterbuilt.  I really think the masterbuilt is measuring the air temp + getting heat soak from the internal cabinet temperature.  I think that's part of the reason for the swings.  Basically it takes longer for the masterbuilt thermometer to register that it needs to kick on because it's absorbing heat from the internal walls.  When I get a chance I think I'm going to take apart the back thermometer and see if I can't insulate it a little better from the walls so I can get a better air temperature reading.  The other idea I had was to add a different ambient air thermo-probe that doesn't sit on the wall and connect that into the controller instead of the built in one.  

 

Fun fun.


All I do is use my Wireless Digital probes near the meat.

Then I adjust the MES control until the Maverick reads what I want.

Other than that I just ignore what the MES says---I only use it to know how much to adjust it.

 

Like if I want 230° smoking temp:

If my Maverick says 220°, and my MES says 230°, then I set the MES to 240°.

In a few minutes the Maverick will be at 230°.

 

And as for the small 10 to 15 degree cycles, I just pick the average & let it cycle all it wants.

 

Bear

post #6 of 25
Quote:
Originally Posted by Bearcarver View Post
 

Hi "nPoc",

That's a pretty common problem with most MES units, and other electric smokers.

 

I wrote this (below) up awhile back to show how I dealt with that problem with my older Generation #1 MES 40.

 

My new Gen #2.5 has a much smaller cycling spread.

 

 

This should help:

http://www.smokingmeatforums.com/t/208552/avoid-temp-swings-in-mes-by-bear

 

 

Bear


Just looked at that old post. I understand what you wrote and I'll give it a try this year but I don't understand the science behind why the controller directs the heating element the way it does to cause those temp swings. I think it'd be interesting to read your more comprehensive procedures for how you tweak your controller to fine tune the controller to keep the swings to a minimum.

post #7 of 25
Quote:
Originally Posted by daRicksta View Post
 


Just looked at that old post. I understand what you wrote and I'll give it a try this year but I don't understand the science behind why the controller directs the heating element the way it does to cause those temp swings. I think it'd be interesting to read your more comprehensive procedures for how you tweak your controller to fine tune the controller to keep the swings to a minimum.


I like to blame a lot of it on "Momentum".

Hard to explain, but I'll try:

 

When you start a cold MES & set it for 250°, it builds momentum & everything inside is heating up as the temp rises. Then when the element stops, all that momentum & building heat continues to rise for various amounts of time (Maybe 30° 40°, or even 50° of over-run).

 

If the smoker is already at 245° & you only change the temp setting from 245° to 250°, once the element shuts off at 250° the Smoker temp doesn't coast much because only moving 5° in temp doesn't cause much momentum at all.

 

Example:

So that explains why if I want to go to 230°, and I normally have a 30° over-run, I would set the MES to 205°. Then when the element shuts off at 205°, the heat coasts to 235°.

Then if I reset the MES to 230°, it will come back on when the temp hits 229°, and it won't fall much below 230° because it won't have the falling momentum, and then again when it goes back up again, it won't go much over 230° when the element goes off, because of no momentum again.

 

Then from there on both the Up Cycle & the Down Cycle should have small over-runs, because all of the Up & Down Cycles are small. And each time the over-run gets smaller, it causes the following over-run to get smaller, again & again & again. Eventually the Cycles should get down as low as 4° to 6° cycles.

 

Hope that helps.

 

Bear

post #8 of 25
Quote:
Originally Posted by Bearcarver View Post
 


I like to blame a lot of it on "Momentum".

Hard to explain, but I'll try:

 

When you start a cold MES & set it for 250°, it builds momentum & everything inside is heating up as the temp rises. Then when the element stops, all that momentum & building heat continues to rise for various amounts of time (Maybe 30° 40°, or even 50° of over-run).

 

If the smoker is already at 245° & you only change the temp setting from 245° to 250°, once the element shuts off at 250° the Smoker temp doesn't coast much because only moving 5° in temp doesn't cause much momentum at all.

 

Example:

So that explains why if I want to go to 230°, and I normally have a 30° over-run, I would set the MES to 205°. Then when the element shuts off at 205°, the heat coasts to 235°.

Then if I reset the MES to 230°, it will come back on when the temp hits 229°, and it won't fall much below 230° because it won't have the falling momentum, and then again when it goes back up again, it won't go much over 230° when the element goes off, because of no momentum again.

 

Then from there on both the Up Cycle & the Down Cycle should have small over-runs, because all of the Up & Down Cycles are small. And each time the over-run gets smaller, it causes the following over-run to get smaller, again & again & again. Eventually the Cycles should get down as low as 4° to 6° cycles.

 

Hope that helps.

 

Bear

You gave me the scientific reasons behind what I've observed for years. It also explains why the temp swings in my MES 30 become minimal-to-none about 3 hours in. I'm giving your procedure a try this year. Thanks, Bear!

post #9 of 25
Quote:
Originally Posted by daRicksta View Post
 

You gave me the scientific reasons behind what I've observed for years. It also explains why the temp swings in my MES 30 become minimal-to-none about 3 hours in. I'm giving your procedure a try this year. Thanks, Bear!


Thanks Rick,

I don't know if we can call it scientific.

It's more like my trying to explain the way I see it & the reasons I figure it happens.

If you get this working for you, that 3 hours could drop down to a very short time after coming to set temp.

 

 

Bear

post #10 of 25
Quote:
Originally Posted by Bearcarver View Post
 


Thanks Rick,

I don't know if we can call it scientific.

It's more like my trying to explain the way I see it & the reasons I figure it happens.

If you get this working for you, that 3 hours could drop down to a very short time after coming to set temp.

 

 

Bear


Bear,

 

Looking forward to giving it a try. Right now the cold temp, a bum shoulder, and fighting off a touch of the flu has sidelined my smoking activities until warmer weather arrives and the other two issues are resolved.

 

Rick

post #11 of 25

I hope you get to feeling better soon, Rick.

 

Bear, I think you hit the nail right on the head when you said that you more or less ignore the swings and just shoot to have the average temperature be what you want it to be.  And your procedure for minimizing the overshoot when first starting the smoker up is actually just what a tuned PID controller tries to do!

 

On the one hand, I'm a smoking nut just like most of us on here, and I plan to modify the heck out of my MES soon.  And I'll try to optimize things, of course.

 

On the other hand, I don't think the temperature swings are too much of an issue.  Ovens have traditionally had wide temperature swings, but they bake and roast just fine.  The meat doesn't care as much as we do.  In fact, it might be argued that temperature swings give us better smoke penetration, or something, kind of like aging whiskey over many years, using the temperature cycles to our advantage.  Who knows?

 

In addition, we need to be extremely careful of how we interpret measurements we make in any oven or smoker.  Things are not always what they seem to be.

post #12 of 25
Quote:
Originally Posted by Sigmo View Post
 

I hope you get to feeling better soon, Rick.

 

Bear, I think you hit the nail right on the head when you said that you more or less ignore the swings and just shoot to have the average temperature be what you want it to be.  And your procedure for minimizing the overshoot when first starting the smoker up is actually just what a tuned PID controller tries to do!

 

On the one hand, I'm a smoking nut just like most of us on here, and I plan to modify the heck out of my MES soon.  And I'll try to optimize things, of course.

 

On the other hand, I don't think the temperature swings are too much of an issue.  Ovens have traditionally had wide temperature swings, but they bake and roast just fine.  The meat doesn't care as much as we do.  In fact, it might be argued that temperature swings give us better smoke penetration, or something, kind of like aging whiskey over many years, using the temperature cycles to our advantage.  Who knows?

 

In addition, we need to be extremely careful of how we interpret measurements we make in any oven or smoker.  Things are not always what they seem to be.


All True:

I do my measuring where it counts---Near the meat.

 

And I do these things to eliminate the big swings, but I don't worry about small swings.

If I'm smoking Bacon at 120°, I don't want 160° spikes. I want my Temps between 110° and 130° for the 120° average.

My method gets rid of the big swings real fast, instead of a long string of big swings.

 

 

Bear

post #13 of 25
Yep. The human PID conroller.

I do this myself, even with ovens that have a PID controller, if the "loading" or temperature is far off from the conditions that were present when we tuned the PID controller. You really can get things running well a lot faster if you set the temperature a bit low to start, then bump it up to the desired setpoint once it stabilizes at the first, lower temperature.

I do that when using my temperature calibrator at low temperatures because the PID controller overshoots at startup at low temperatures even though it is well tuned for higher temperatures. They make controllers that let you tune them at a number of different temperatures, and then the controller chooses the tuning parameters for the closest temperature to the setpoint that you're using right then. I really should set that up in my calibrator. But I just do what you do, and start off with a lower setting than what I want, and bump it up once it settles in at that first setpoint.

A great example of how us humans act as a fantastic PID controller is how well most people do at regulating the speed of a car when driving. We don't even think about it, yet we can get the car from a stop to the desired speed with no overshoot, undershoot, or ringing just by feathering the throttle back as we close in on the desired speed. That kind of intelligent control is what inspired the development of modern PID algorithms, I'm sure.
post #14 of 25

Exactly!!

 

Bear

post #15 of 25
I know alot of folks hate wasting fuel, but I always pre-heat my MES for at least an hour to let things stabilize. I also always pre heat the water in my pan and and add pre heated water to my water pan when needed. I use the side burner on my grill to heat water before adding to the pan. I also drape a welding blanket over the unit for some added insulation and added an external smoke generator so I could control smoke without opening the cabnet...These things did help but I still have temp swings during cycling, though not as drastic.
post #16 of 25
That's what I usually do with the smoker, too. I like having it pre heated so the inside walls and everything is up to temp before I put the meat in. Plus, I can have the pellets in the amnps during that pre heat, and that gets them nice and dry, which is important for me here.

Once I set up a mailbox, I might still pre-cook the pellets in the smoker before moving the pre-filled, and pre-dried amnps to the mailbox. An hour of pre heating costs about a dime here.
post #17 of 25
Quote:
Originally Posted by jokensmoken View Post

I know alot of folks hate wasting fuel, but I always pre-heat my MES for at least an hour to let things stabilize. I also always pre heat the water in my pan and and add pre heated water to my water pan when needed. I use the side burner on my grill to heat water before adding to the pan. I also drape a welding blanket over the unit for some added insulation and added an external smoke generator so I could control smoke without opening the cabnet...These things did help but I still have temp swings during cycling, though not as drastic.
Quote:
Originally Posted by Sigmo View Post

That's what I usually do with the smoker, too. I like having it pre heated so the inside walls and everything is up to temp before I put the meat in. Plus, I can have the pellets in the amnps during that pre heat, and that gets them nice and dry, which is important for me here.

Once I set up a mailbox, I might still pre-cook the pellets in the smoker before moving the pre-filled, and pre-dried amnps to the mailbox. An hour of pre heating costs about a dime here.

 

Hi Guys,

I preheat between a half hour & an hour too.

 

As for the Pellets, I keep them in air tight plastic Half Gallon Jugs, so they never need heating to Dry. I light them outside of the smoker when I turn the smoker on, so they have time to get going good before I put the Amazing in the smoker. I have some for 5 years that still light & keep smoking like the new ones.

 

As for Water in the Pan---I haven't put water in my Water Pan for the last 6 years. There are more reasons to NOT put water in than there are to put water in.

 

 

Bear

post #18 of 25
Quote:
Originally Posted by Sigmo View Post

Yep. The human PID conroller.

I do this myself, even with ovens that have a PID controller, if the "loading" or temperature is far off from the conditions that were present when we tuned the PID controller. You really can get things running well a lot faster if you set the temperature a bit low to start, then bump it up to the desired setpoint once it stabilizes at the first, lower temperature.

I do that when using my temperature calibrator at low temperatures because the PID controller overshoots at startup at low temperatures even though it is well tuned for higher temperatures. They make controllers that let you tune them at a number of different temperatures, and then the controller chooses the tuning parameters for the closest temperature to the setpoint that you're using right then. I really should set that up in my calibrator. But I just do what you do, and start off with a lower setting than what I want, and bump it up once it settles in at that first setpoint.

A great example of how us humans act as a fantastic PID controller is how well most people do at regulating the speed of a car when driving. We don't even think about it, yet we can get the car from a stop to the desired speed with no overshoot, undershoot, or ringing just by feathering the throttle back as we close in on the desired speed. That kind of intelligent control is what inspired the development of modern PID algorithms, I'm sure.


So that's been my problem. I play around with adjusting the temps to offset the upswing when I should be waiting for it to stabilize, which it typically does, more or less, 3 hours into the smoke.

post #19 of 25
Quote:
Originally Posted by Sigmo View Post
 

I hope you get to feeling better soon, Rick.

 

Bear, I think you hit the nail right on the head when you said that you more or less ignore the swings and just shoot to have the average temperature be what you want it to be.  And your procedure for minimizing the overshoot when first starting the smoker up is actually just what a tuned PID controller tries to do!

 

On the one hand, I'm a smoking nut just like most of us on here, and I plan to modify the heck out of my MES soon.  And I'll try to optimize things, of course.

 

On the other hand, I don't think the temperature swings are too much of an issue.  Ovens have traditionally had wide temperature swings, but they bake and roast just fine.  The meat doesn't care as much as we do.  In fact, it might be argued that temperature swings give us better smoke penetration, or something, kind of like aging whiskey over many years, using the temperature cycles to our advantage.  Who knows?

 

In addition, we need to be extremely careful of how we interpret measurements we make in any oven or smoker.  Things are not always what they seem to be.


Thanks, Sigmo. My shoulder problem is either just old age arthritis or it's a rotator cuff thing. I find out early next month. At least I don't have the flu.

post #20 of 25
Quote:
Originally Posted by Bearcarver View Post
 

 

Hi Guys,

I preheat between a half hour & an hour too.

 

As for the Pellets, I keep them in air tight plastic Half Gallon Jugs, so they never need heating to Dry. I light them outside of the smoker when I turn the smoker on, so they have time to get going good before I put the Amazing in the smoker. I have some for 5 years that still light & keep smoking like the new ones.

 

As for Water in the Pan---I haven't put water in my Water Pan for the last 6 years. There are more reasons to NOT put water in than there are to put water in.

 

 

Bear

 

I never use the water pan, either.  If I do, the moisture kills the the pellet burn.  Things gotta be really dry at this elevation.

 

And I have to pre-dry the pellets here.  At 5300', the air is just too thin for reliable burning without taking every possible step.  If I dry them in my oven, I then put them in sealed jars, and they're ready to go.  If I'm doing a cold smoke, I really need the pre-dried pellets from the jars.  If I'm smoking at a high temperature, then the draft through the smoker is better, for one thing, and I also have the opportunity to use the pre-heating smoker to get the pellets really dry.  So that works great.

 

If I end up using the AMNPS inside of the smoker once I have the little stirring fan installed, I suspect it'll make them burn too fast by keeping the air moving.  So then I'll probably be looking for a way to slow the things down!

 

Of course, with the AMNPS in a mailbox, any stirring inside of the smoker won't have any effect on the burn.  So then I'll be back to finding ways to make them burn reliably again, most likely.  ;)

 

But it's all a lot of fun to tinker with.

 

Meanwhile, I smoked a batch of Pecans the other night, and everything worked dandy.  I ran it set to 225, and it was about 25 to 30 degrees outside.  With the modifications I've made to the smoker, the pellets burned just right, and the nuts came out dandy.  Hopefully the "improvements" I plan to make will actually make things work better.  But there's always the distinct possibility that it'll all cause unintended problems.  Still, it's fun.

 

My wife wants me to smoke a couple more pork butts because we just ate the last of the frozen pulled pork from the last time.  What we don't eat immediately, I vacuum seal in bags holding enough to make a good meal for two.  Then it's fast to heat up, and makes for a tasty "fast food" treat.  If I get some modifications done before I do the butts, then I'll have to learn as I go again because it'll change things.  Right now, I've got the procedure down to a sure-thing.  But where's the challenge if it always works right? 

 

Quote:
Originally Posted by daRicksta View Post
 


So that's been my problem. I play around with adjusting the temps to offset the upswing when I should be waiting for it to stabilize, which it typically does, more or less, 3 hours into the smoke.

 

The thing I find is that the dynamics of it all change during the course of any smoke because the meat is warming up and drying out.  So the amount of "damping" that the meat provides to the system is ever-changing.  At first, I've got a large mass of cold, wet meat.  And as the meat warms up and dries out, the "load" that it puts on the system decreases.  So things are never tuned ideally over the whole smoke.  Usually, I just don't worry about it, and let the MES do its thing, and the meat comes out fine.

 

The modifications I intend to make will be trying to create a system where the temperature is more even throughout the whole smoker, and held to a closer tolerance with respect to time, too.

 

But assuming I'm successful in getting the system to hold a more constant and steady temperature, and keep things even throughout the whole smoker, what will be interesting will be to see if that improves the end product.  It seems like it should, but I'm also sure it'll require a learning curve for me because I think the food will cook faster.


The instructions for our convection oven say that if you use the convection mode, you either need to shorten the cook time or use a lower temperature.  With a smoker, I kind of like long cooking times because they give more time to apply the smoke.  And I worry that having the air actively circulated may make the surfaces of the meats dry out faster.  Maybe that will make the smoke fail to penetrate or "stick" as well.

 

For doing jerky, I think it'll be great.  For doing something like poultry, maybe it'll let me get crisper skin.  But for something like a Boston Butt, maybe it'll be a disadvantage.  I'm sure it's going to take some trial and error to get used to it.

 

The advertising hype I was reading for some of the commercial smoking ovens really made a big point of how they managed the air movement within the smoker to get consistent cooking times and smoke application throughout the whole chamber.  The really stressed that everything would be done at the same time, cooked to the same IT, and smoked the same.  And the ways they achieved this always used fancy fan-forced circulation, often with sets of dampers that were motorized to create back and forth air flows at different times in different areas to really try to keep the heat and smoke evenly applied everywhere in the large volumes of these big commercial smokers.

 

I think with our smaller smokers, it's less of an issue, but it's still a consideration, particularly when doing multiple items placed throughout the smoker.  If I'm just cooking one Butt, or a turkey, etc., then it's not much of a worry.  But if I do multiple little birds, or butts, or fill the thing up with jerky, then it really does become important to have the same conditions everywhere in the smoker.

 

I've removed all of the factory "guts" of my MES 40 except for the actual heating element and the support rods and that cross piece down there.  Instead, I've got something similar to what a lot of you folks have, designed to move most of the heated air over towards the middle of the chamber which also directs the airflow towards the AMNPS's position.  This has given me much more reliable burning of the pellets.  And It also seems to give me better consistency throughout the chamber.

 

It's entirely passive, using only the convection draft through the smoker, though.  So it really doesn't do much for me during cold smoking when there is no "draft".  So I've used a computer fan, running on a lower voltage, inside of the smoker to stir the smoke around when doing cheese and butter. And that's worked well.  But I do look forward to being able to have active stirring even when doing hot smokes.

 

Quote:
Originally Posted by daRicksta View Post
 


Thanks, Sigmo. My shoulder problem is either just old age arthritis or it's a rotator cuff thing. I find out early next month. At least I don't have the flu.

 

I hate the flu!  Then again, don't we all!  :)

 

I have a bit of that shoulder thing myself.  But so far, it hasn't caused me enough grief to go in for the MRI that was suggested. I suspect that time will come, however!  I hope you get good news, or at least you end up with a diagnosis that suggests a good, solid fix for it.

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