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Has Anyone Fooled the MES Temp Sensor Before? - Page 3

post #41 of 68
Quote:
Originally Posted by CFLBob View Post
 

Bear, did you have that piece of aluminum sheet lying around or did you buy it someplace?  Is it some sort of Home Depot part?  I don't have any sheets that size, and the only sheet I have is 1/8" thick anyway.  I wouldn't use 1/8 sheet in the smoker, it's too useful for other projects.  


That's one of the Perks I get for having a Son who has his own Tower Corp.

The aluminum I used was a cut-off from the 12' top of a cable tray.

 

However Home Depot should have all kinds---Try the aluminum siding & flashing area.

 

 

Bear

post #42 of 68

I have a MES 40-2.5 and used a 1/4 aluminum sheet pan from the restaurant supply as the bottom deflector. Fit is almost perfect but I had to cut the corners on one side and bend it down to fit over the water pan. The sheet pan fits fairly snugly although there are small gaps around the edges, especially at the glass door. It sits on top the water pan and the pan extends beyond it thereby splitting the rising hot air in half that I think makes for more dispersal of the hot air up the side opposite the heating element and the top exhaust port. The pan also fits in the dishwasher for cleanup.

 

I want to add the bent extension ducting like Bear has attached to the roof. But, it seems like with the bottom deflector the next greatest impact is the meat load and how they change the airflow. The roof ducting should mitigate those variances. Top rack and next to the door's glass is always the coolest area but the glass area will finally get close if I leave the door closed for +1 hour.

post #43 of 68
Quote:
Originally Posted by Sundown Farms View Post
 

I have a MES 40-2.5 and used a 1/4 aluminum sheet pan from the restaurant supply as the bottom deflector. Fit is almost perfect but I had to cut the corners on one side and bend it down to fit over the water pan. The sheet pan fits fairly snugly although there are small gaps around the edges, especially at the glass door. It sits on top the water pan and the pan extends beyond it thereby splitting the rising hot air in half that I think makes for more dispersal of the hot air up the side opposite the heating element and the top exhaust port. The pan also fits in the dishwasher for cleanup.

 

I want to add the bent extension ducting like Bear has attached to the roof. But, it seems like with the bottom deflector the next greatest impact is the meat load and how they change the airflow. The roof ducting should mitigate those variances. Top rack and next to the door's glass is always the coolest area but the glass area will finally get close if I leave the door closed for +1 hour.

 

 

If you trap too much heat in the bottom of the MES, it can warp and it can also burn up the electronics that are buried in the floor.....  

post #44 of 68
Quote:
Originally Posted by Sundown Farms View Post
 

I have a MES 40-2.5 and used a 1/4 aluminum sheet pan from the restaurant supply as the bottom deflector. Fit is almost perfect but I had to cut the corners on one side and bend it down to fit over the water pan. The sheet pan fits fairly snugly although there are small gaps around the edges, especially at the glass door. It sits on top the water pan and the pan extends beyond it thereby splitting the rising hot air in half that I think makes for more dispersal of the hot air up the side opposite the heating element and the top exhaust port. The pan also fits in the dishwasher for cleanup.

 

I want to add the bent extension ducting like Bear has attached to the roof. But, it seems like with the bottom deflector the next greatest impact is the meat load and how they change the airflow. The roof ducting should mitigate those variances. Top rack and next to the door's glass is always the coolest area but the glass area will finally get close if I leave the door closed for +1 hour.

 

 

I don't do any ducting at the top. All I do in my MES Gen #1 is the heat deflector at the bottom, and it shouldn't fit too tight, and the left side should be higher than the right side. None of this is needed in my MES Gen #2.5.

And like Dave & I have both said, you don't want to trap heat down there---It could do damage to the Smoker.

 

Bear

post #45 of 68
Just had a thought. I wonder if the mes cabnet temp sensor and the mes meat probe had have the same parameters. If so, one could just switch the wires and put the meat probe wherever you want. Or, if you could remove the cabinet sensor, extent its wires and make a dohicky to hang it wherever you want?
post #46 of 68

I know this is long, so bear with me if you want to:

 

 

It probably isn't a bad assumption to think that they'd use the same type of sensor element for both of these probes since it would simplify the design of the controller.  So they might both be thermistors of the same type.

 

And it's not a terrible idea to have a moveable sensor for the controller so that you could force the unit to maintain the temperature at your desired test point to be what you want.

 

But you would want to be very cautious with any such modification and the implementation of it.

 

It's important to realize that the position, shape, thermal time constant, etc., of the sensor that reports back to the controller so it can control the power to the heater are all part of the design of the system.

 

The position of their sensor, right above the heating element, and its size and speed of response have all been "tuned" along with the program in the controller to achieve the response that the designers want.

 

We can imagine that the sensor, right where they have it, "sees" the heat coming up off of the heating element fairly directly.  This causes the system to shut off the heater sooner than it would if the sensor was located somewhere farther from the heating element, and out of the direct path of warm air rising up from it.  So the speed of cycling on and off of the heating element is likely faster with the sensor right where it is than it would be if you placed the sensor farther away from the heating element.

 

If you place the sensor in some place that you feel is more representative of the actual temperatures that the meat is experiencing, that has the advantage of forcing the smoker to drive that temperature to the setpoint you've programmed.  And this seems, at first glance, to be a good thing.


But what you have to remember is that this could cause a dangerous situation, and further, it's not necessarily what you really want in terms of making your cooking match what you see in various recipes.

 

As an extreme example:


Let's say we swap the meat probe and the controller sensor on one of these smokers.

 

Now, we want the unit to control the temperature that our pork butt is actually experiencing.  So we put the meat probe fairly near to the pork butt, and fire up the smoker.

 

Right away, the heating element comes on full blast.  But it stays on for a very long time because the sensor is near to the pork butt, and the cold temperature of that butt, along with the moisture in it, creates an area around it that is fairly cool compared to areas in the smoker farther from the butt.

 

So the temperatures seen by the hottest places in the smoker (presumably down near the heating element, and other areas farther from the big piece of meat) end up being far higher than the setpoint we've punched into the controller.  The controller thinks it needs to keep the heater on, yet the temperatures in the hottest parts of the smoker may be dangerously high. High enough to start decomposing the foam insulation in the back or sides of the smoker nearest to the heating element.

 

Further, even if the temperatures don't become dangerous, the heater may cycle on and off very slowly.  Perhaps staying on for half an hour or an hour at first before our probe "sees" the temperature we wanted.  And then, once it does "see" that temperature, so much heat might be stored in the system that the heating element will now remain off for a very long time before things cool down enough to cause it to cycle on again.

 

Cooking recipes take into account the phenomenon of the actual air temperature right near the big thing being cooked taking a long time to come up to match the "oven temperature".

 

With a so-called convection oven (misnamed IMO because they use the OPPOSITE of convection, and instead rely on a fan to actively circulate the air). things cook faster than in a "normal" oven.  This is because the active fan-stirring of the air gives you a more uniform temperature throughout the oven and constantly forces this "proper temperature" air over the item being cooked.  So it doesn't have this layer of cool air surrounding it.  Instead, it's continuously exposed to air that is closer to the actual oven temperature setting.

 

So you have to consider the effects on cooking time in all of this.

 

Further, from a control-system tuning point of view, consider this:

 

In many laboratory drying ovens, incubators, etc., I have seen the temperature sensors placed in the direct path of the heated air coming off of the heating elements.  At first, I thought this was silly because everyone knows that you don't put your home heating system thermostat right above a heat register, or it'll shut off too early and never get the main living space up to the correct temperature.

 

But there is a method to their madness!  It's part of how they "tune" the controller that maintains the oven's temperature.  It effectively speeds the response of the system, and lessens the amount of temperature swing between the "ON" and "OFF" parts of the cycle.  It also acts as a safety feature because although parts of the oven are, indeed "too cool", we know that no part of the oven is ever "too hot".  And that's the tradeoff they make.

 

As we cook something in an oven or smoker (or as we dry samples in a laboratory drying oven), we do NOT want any part of the food or samples to get above the oven senpoint temperature.  Food can burn or dry out, and samples might go over the upper temperature limit set forth in a particular analytical method, and thus give invalid results because you drove off things that would not be volatile if you stayed below the prescribed upper temperature limit.

 

So always keep in mind that unless you're prepared to reprogram the controller and carefully troubleshoot all of the side-effects of tampering with the factory design, you probably should keep things pretty much as they are.

 

The easy method people have used on here is to simply set the controller to a temperature a bit above what you normally would if you want a higher cooking temperature.  And they base this "offset" on what they read with their moveable probe thermometers/loggers.  Still, they need to keep in mind that many of the recipes we see are based on an unmodified smoker that was set using the factory control system with no adjustments or modifications.  And measuring the temperature in one particular place may not really be telling us the whole story.

 

Still, I do sympathize with people thinking that their smoker's actual temperature is incorrect.  And clearly, these inexpensive smokers don't have the best possible control systems, and I'm sure some are way off.  Just be careful and realize that measuring the actual temperatures in an oven is a bit more involved than we might think.  There can be HUGE variations in temperature from one place to another, especially if there is no active stirring of the air.  I've seen laboratory ovens with 15 degrees C (27 degrees F) of difference between probes placed several INCHES apart!  I've had PhD chemists complain to me that my monitoring system was way off due to this, only to later prove to them that the system, and a number of separate probes were, in fact, all in agreement with a NIST traceable thermometer to within 1/100th of a degree C!  Indeed, it was simply variations in temperature within small distances in these ovens that was real.

 

So we need to be extremely diligent in our assessment of temperature accuracy.  What we see with our fancy external thermometer or data logger may well be true.  But only for the very place and time where it's probe happened to be.  So I don't like to be too quick to impugn the accuracy of the factory probes or controllers in any oven or smoker.

 

But again, I also know they aren't perfect.  And for what these systems cost, I'm sure people get real lemons.  My MES's sensor/controller is quite non-linear.  And while it's very accurate at room temperature, it gets farther and farther off as we get up into cooking temperatures.  But so far, I have found that if I set the unit to the temperature the recipe calls for, even though I've proven that its temperature sensor is not linear, and is off, perhaps 20 degrees at 225, the food cooks to the correct internal temperatures in times that match up pretty well with what other people post in their recipes and other posts on here.

 

Also, we all find that we have to make trial-and-error adjustments to our recipes anyhow because our humidity, ambient temperature, elevation, etc., all play into this.  So none of it is exact.  Our smoker calibration is just one of the variables we have to account for with our trial and error.


What I DO want to be dead-on is my meat probe, though!  And fortunately, in my MES, the meat probe is within a degree or so over the whole range.  Maybe I lucked out.  I don't know.  Maybe the meat probes are different.  And maybe, just maybe, the bizarre non-linear calibration of my MES's controller sensor was done on purpose to make the actual response in the main part of the cooking chamber end up being correct.  Perhaps that's giving MB too much credit.  But the fact is, I just don't really know.

 

But because my MES's meat probe IS so accurate, I can use it in different places in the chamber to see what the temperature is doing, and then make manual adjustments to the controller's setpoint to get what I want during different parts of a smoke, or just to keep an eye on it.


I once placed the meat probe just below where a large pork butt was being smoked, suspended in some paper clips so it was about an inch below the butt.  It was very interesting to look at that temperature and see it go up very slowly during the first hours of the smoke.  I didn't change anything based on those readings, but it was interesting to see how the temperature right there stayed fairly low, initially, probably in part because of the moisture on the surface of the butt.  Then, as it formed a pellicle or bark, the temperature right under the butt finally started to rise.  It's interesting information.  Not because I wanted to adjust the temperature of the smoker, but because it helped show me what the temperature near the butt was actually doing during a typical smoke in a non-stirred oven environment.

 

It's nice to have a known accurate, moveable probe that you can use to tell you what's going on in different places within our smokers.  Just don't be too quick to think you need to change things.  Millions of non-technical people make millions of great meals in their factory-stock smokers.  Ignorance is bliss, I guess.

 

Still, I'm a tinkerer, and for me, and clearly a lot of us on this forum, we LOVE to play with all of this, and we want to understand what's going on, and we want to optimize things.  And really, that is a big part of the fun in all of this. And I do not dispute that some of these smokers really do have calibration problems.

 

In the spirit of experimentation, hobbyist enjoyment, and just plain Smoker Nerdism, I am planning a serious modification of my MES, using different sensors, and a stirring fan from a convection oven.  So I am right with you in this!

 

But I will leave the snap-disk safety cut-off in the circuit that feeds the heating element.

 

And I've already modified the air intake and heating element area with different baffling to get better pellet burning along with heat and smoke distribution in the smoker.  But I have made sure that some of the heat from the heating element still has a good "straight shot" up to the sensor.  I don't want to circumvent the control system's tuning too much until I do the full modifications I have planned.  At that point, a lot of things will change, particularly because of the stirring fan.

 

What I've got in mind is to use the stirring fan to keep the temperature and smoke fairly even throughout the chamber.  And I'll also use a different sensor to inform the controller of the oven temperature as well as a couple of "free to move" sensors to give me information about what the temperature is doing in selected places within the smoker.  And finally, I've got a new meat probe as well because I want the controller (and me) to be able to keep track of the meat probe temp, and I have no interface that can read the factory style thermistors.

 

Hopefully, as I do this, it will yield some interesting and useful information about what the temperatures really do in different places inside of one of these smokers. Two of the thermocouple sensors I got have alligator clips so you can easily move them and hang them in different places.  They came from the manufacturer that way!  How cool is that?

 

I love experimentation.  Just be safe, and consider the consequences of various modifications.

 

All of this is great fun, IMO!


Edited by Sigmo - 1/20/17 at 4:29pm
post #47 of 68

Sigmo - Thank you for taking the time to share so many significant thoughts. I like checking the temps inside the MES and have found there are so many things beyond the design of the MES that cause variations in every smoke that the thing to do is relax, set it up like the last time the meat was great and enjoy the day.  Thanks again!!!

post #48 of 68
Thread Starter 
Quote:
Originally Posted by Sigmo View Post

 

What I've got in mind is to use the stirring fan to keep the temperature and smoke fairly even throughout the chamber.  And I'll also use a different sensor to inform the controller of the oven temperature as well as a couple of "free to move" sensors to give me information about what the temperature is doing in selected places within the smoker.  And finally, I've got a new meat probe as well because I want the controller (and me) to be able to keep track of the meat probe temp, and I have no interface that can read the factory style thermistors.

 

Hopefully, as I do this, it will yield some interesting and useful information about what the temperatures really do in different places inside of one of these smokers. Two of the thermocouple sensors I got have alligator clips so you can easily move them and hang them in different places.  They came from the manufacturer that way!  How cool is that?

 

I love experimentation.  Just be safe, and consider the consequences of various modifications.

 

All of this is great fun, IMO!

 

I've already PID'ed a used Gen2 MES I got for dirt cheap andI think I'm about to reach the fan part of my journey soon.  I'm finding that the PID prob (which is small) is getting hidden behind meat and pans and such and not reading as well as the Maverick probe (much much larger).  If airflow was more even then it wouldn't matter where I put the PID probe.

 

I've been researching convection ovens and such and I think I can create a makeshift convection type setup.  I'm looking at the following mod that would include a fan for convection type air flow and the mailbox mod with ANMPS spliced in:

 

- 3 inch duct Tee

 

 

 

 

-3200RPM 80mm (just over 3 inches) Fan

 

 

-Mailbox mod I already have in place

 

 

 

Basically hook the Tee into the MES.

Hook the fan to the back end of the Tee.

Hook the mailbox mod to the underside of the Tee

 

I would end up making something like the following photoshop'ed image:

 

 

 

The only thing I am lacking is a concrete calculation of how much fan and speed I need/want for the volume of air I need to turn over in the MES40.  I can find bits and pieces of info on convection cure oven, hvac temp management, and dimensions of convection oven parts and oven sizes along with fan speeds (RPMs).  However I cannot find a definite statement of "here is how you calculate fan size and speed for air volume" of a convection oven.

 

Sigmo, maybe you have some insight?

The best I can do is try to replicate what convection ovens are doing as best as I can within the confines of the MES dimensions and not completely hacking up the smoker to use an actual convection oven fan.

 

[Edited to strike through because CFM is probably the metric I need to work with not RPM, learned it here https://ftiinc.org/4-best-features-make-oven-airflow-better/]

So a 3200 RPM fan with a roughly 3 inch diameter fastened to 3 inch ducting is about the best I could do within the limitations of the MES in an attempt to mimic 150mm ( almost 6 inches) 4000 RPM convection oven fans I looked up.  Most of those fans operate on a low setting of 900-1000 RPM's so I'm hoping that 3200 RPM out of a 3 inch fan would be roughly equivalent to the min speeds of the 6 inch convection fans or fall between the min and max speeds for those same convection fans.

 

Ok the MES40 has no more than 24 cubic foot of space (calculated from outer dimensions, couldn't find inner dimensions and I'm not near to measure).

So the fan I looked up is a 22 CFM so it should pump 22 cubic feet of air per minute.  So every minute the air could technically circulate in the MES (barring issues bouncing around, etc.).

Now I just need to figure out the desired circulation per minute for cooking.   

 

That's the best I have so far.  Any input from the community would be appreciated. Thanks :)


Edited by TallBM - 2/14/17 at 9:53pm
post #49 of 68
The problem I see with this is that you are introducing cold air to the box, as opposed as to recirculating the existing air. This could make it hard to maintain higher temps inside the box.
post #50 of 68
Thread Starter 
Quote:
Originally Posted by FloridaSteve View Post

The problem I see with this is that you are introducing cold air to the box, as opposed as to recirculating the existing air. This could make it hard to maintain higher temps inside the box.

Good point. Thanks for waking me up hahaha.  

I got so carried away with researching the ins and outs of circulating air that I totally failed to keep that detail in mind!

 

Well I did see an example on the internet of a fan simply installed into the smoker with the motor on the outside, see image below:

 

 

 

 

With that setup I think I can apply a bit more of what I have been learning and see what/if anything is possible.  I like how simple that mod seems but I have to dig into it a bit more.

 

Please feel free to poke any obvious holes into these ideas or offer solutions.  Thanks for the input! 

post #51 of 68

My cables and probes clip/lay/hang/suspend from the rack above the meat so no obstruction. I made rtv silicone pucks, the clips the probes came with are clipped on the underside of the rack above the food. Use wooden clothes pins. Get probes/cables away from your food that aren't in the food. Dont let finding a home for your chamber probes be your demise.
-Kurt
post #52 of 68
Thread Starter 
Quote:
Originally Posted by Dr K View Post


My cables and probes clip/lay/hang/suspend from the rack above the meat so no obstruction. I made rtv silicone pucks, the clips the probes came with are clipped on the underside of the rack above the food. Use wooden clothes pins. Get probes/cables away from your food that aren't in the food. Dont let finding a home for your chamber probes be your demise.
-Kurt

 

Thanks for posting your solution.  Maybe i can take a bigger champagne cork and put the little probe through it and pull through some excess chord so I can then let it dangle through a rack above meat.  I will try and mimic your design with a cork and see what happens. 

 

So far I've tried to utilize a little flue tape and a small stainless steel hook to try and rig up a hanging mechanism for my PID smoker probe.  The squeeze clip is just not working out and is barely small enough for the probe to fit in it.   The PID probe is the small and doesn't want to cooperate so well with my make shift hook addition. I will look into the alligator clips as well. Thank goodness the maverick probe has no issues.

post #53 of 68
Quote:
Originally Posted by FloridaSteve View Post

The problem I see with this is that you are introducing cold air to the box, as opposed as to recirculating the existing air. This could make it hard to maintain higher temps inside the box.

That's right.


The way I am thinking about all of this is that the stirring/circulating of the air within the smoker is independent of the air flow through the smoker.

 

So, as TallBM points out in a later post, what we want (for circulating the air within the smoker) is a draft inducer type fan which stirs the air within the smoker itself, but which does not directly affect the flow of air through the smoker.  This is exactly the type of fan I've got and am considering installing into my MES 40.

 

The airflow through the smoker (the "draft", if you will) can then remain the same as it always was, being driven entirely by the convection (warm, lower-density air rising due to its buoyancy with respect to cooler, denser air).  Or, a separate forced-draft system can be used to force air through the smoker if desired/needed.

 

I think it's best to think of these two air-flows as being separate, and separately controlled or adjusted.

 

Quote:

Originally Posted by TallBM View Post
 

Good point. Thanks for waking me up hahaha.  

I got so carried away with researching the ins and outs of circulating air that I totally failed to keep that detail in mind!

 

Well I did see an example on the internet of a fan simply installed into the smoker with the motor on the outside, see image below:

 

 

 

 

With that setup I think I can apply a bit more of what I have been learning and see what/if anything is possible.  I like how simple that mod seems but I have to dig into it a bit more.

 

Please feel free to poke any obvious holes into these ideas or offer solutions.  Thanks for the input! 

 

That fan is very much like the one I got to try in my smoker.  I got a used fan meant for a convection oven.

 

(Darn how I hate that term:  "Convection Oven")!

 

Convection is the effect where air circulates due to differences in density, usually due to temperature differences.  As you heat air up, it wants to expand.  If the pressure is kept the same, it "swells up" if you will.  Naturally, when the air expands, its density goes down because the same number of molecules are now occupying more space.  So any given volume has less molecules and therefore less mass.  This is why a hot air balloon has lift or buoyancy.

 

Anyhow, it is this effect that causes convection.

 

But in a "convection oven", a fan is used to stir the air, NOT convection!  So the terminology is completely backwards and counterproductive, creating more confusion among people, which is a real crime IMO.  Whoever coined the term and applied it to a fan-forced oven should be ashamed of themselves.

 

Anyhow, I got a used fan from a "convection oven".  They're designed for just the kind of use we're proposing here.  The design uses a long shaft to separate the "hot end" (the fan and end of the shaft that is inside of the oven or smoker) from the "cool end" (the end where the bearings and motor are - outside of the oven or smoker).

 

There is also a separate, smaller set of fan blades back near the motor and bearings to help keep it even cooler and to draw heat that travels down the shaft out of the shaft before it enters the front set of bearings.  This all helps allow such a fan to last a long time despite the main fan blades being inside of a very hot oven.

 

I need to drill a hole through both the inside and outside layers of the smoker body, and through the insulation between those layers.  I want the hole to be small so that I don't create a puncture in the oven and an unwanted path for airflow into or out of the oven.  But I also don't want the shaft to rub on the inside of the holes, so that's a tradeoff.  It'll never be perfect.  I also need to build an enclosure around the fan motor to protect it from the elements and to provide a grounded safety "cage" around the open electrical contacts on my fan's motor.  But I do want the fan motor to be able to stay cool, so I may put some ventilation openings on the bottom of its enclosure, and make it out of aluminum for best heat transfer to the outside.

 

The power wiring for this fan will enter this safety/protection enclosure through a normal electrical box fitting or conduit gland bushing, etc.  Electrical safety is a concern as is physical protection of the motor.

 

I'm still considering the best placement of the little stirring fan.  I want it to blow air over the heating element of the smoker to some degree and stir the entire cabinet as well as possible.  We'll never have the kind of fancy airflow control like what is mentioned in that article you linked to, but I'm hoping it can be made considerably better than what I have right now.

 

I'd also prefer to place some kind of protective screen over the fan blades inside of the smoker to prevent accidental contact with them either by food or my fingers!  The placement of the little fan will need to be such that it doesn't interfere with the grates, etc., too.

 

I also think I may set up my control system to cycle the fan on and off rather than leaving it on 100% of the time.  In my home "convection oven", the fan switches on and off.  It may cycle on and off with power to a heating element that surrounds the fan, but in any case, it's not on all of the time.   It cycles frequently enough, though, that it probably does keep the air well stirred.

 

It may be that running it 100% of the time is too much, drying things out or making things cook too rapidly.  But in any case, having the ability to adjust (or have the controller adjust) the fan's duty cycle will let me play with that to get good stirring without having it be too much.  I think there are good reasons for not directly controlling its speed, but instead cycling it on and off.  And since that's easy enough to do, I plan on doing it that way.  As that article points out, the hot air can be made to sweep the cold air out from around the "product" and then left there for its heat to soak in for a while, then stirred again, etc.

 

One of the advertising sites I see for a manufacturer of these commercial smokehouses uses a set of dampers operated by a motor drive, that constantly move to make the "breakpoint" they mention move from place to place within the smokehouse.  They make the same point about sweeping the cool air away from the product, replacing it with the heated air, then letting the heat from that hot air soak into the product in that particular place while the smokehouse moves the breakpoint on to another place within the cooking chamber.


In our case, the chamber is small (like my home convection oven), so simply cycling the fan on and off probably stirs the air within the whole volume all at once, then, while the fan is off, you get that soaking-in phase.  I sort of get the feeling that they want to periodically stir the air to displace the layer of cold air that builds up around the "product", and replace it with hot air, but then they let it rest that way for a short time, then repeat that process.  Perhaps this gives less drying of the product yet achieves the even, faster cooking.  So I do think this is something to consider.

 

My hope is to get even cooking and smoke throughout the whole chamber regardless of how I load the "product" in.  Of course nothing is perfect, and I think it'll still be wise to arrange chunks of "product" in ways that lend themselves to good airflow around and between them to help keep things even.  But having a fan stirring the mix every so often should be a LOT better than just letting the air sit stagnant in the smoker.

 

 

Of course, now we get to the other airflow.  That's the air flowing through the smoker.

 

My feeling is that it will always be beneficial to be able to control that airflow separately from the stirring airflow.  And we'll have that by using a stirring fan as you've shown in your pictures above.

 

I figure the actual "convection" or "draft" will still suffice to let us use our mailbox type smoke generators.  The smoke generator won't even know if the stirring fan is on or off.  It'll behave, and the draft will be the same as it always has been.

 

But I'm not currently using a mailbox mod.  I just put an AMNPS inside the smoker, and have the inside ducting/baffling set up to draw air over the AMNPS by convection up and out of the vent at the top of the smoker.

 

I won't be able to do that once I have the stirring fan in place. At least not without some kind of modification.  I think the best will be to move the AMNPS outside of the smoker, into a mailbox mod setup, so that the airflow over the pellets will be independent of the air movement inside of the smoker.  So that will all have to happen at the same time as my installation of the stirring fan.

 

I guess I could do something to shield the AMNPS from the blowing of the stirring fan, and maybe continue to use it inside of the smoker.  But there are other good reasons to move the smoke generator completely outside of the smoker, too, and I've been planning on doing a mailbox mod anyhow, so I'll likely go that route ultimately.

 

Now, we also get to the idea of using a fan to force or regulate the airflow through the smoker.  And, perhaps a separate fan or way to regulate the combustion air over our burning wood chips or pellets, etc.  you could end up with three fans if you wanted to control all three air flows separately!

 

But simply adjusting the position of the damper at the top vent of the smoker, and playing with the positions and sizes of the air inlet openings in a mailbox will still work just as it does in a non-stirred smoker.  So actively controlling the draft and combustion air can be played with as separate projects.

 

 

I tend to think that having control over all of that would be handy, though.  For doing jerky, for example, one might run the stirring fan constantly, and force more air through the smoker than normal to aid in drying it during the later phases of the process.  Yet we'd want to keep the smoke density at some ideal level the whole time, so having independent control of all three air flows could come in handy there.  Or for crisping the skin on a turkey or chicken, we might want to do the same kind of thing.  On the other hand, for a lot of other smoking, we may not want so much air flow through the smoker so that things stay more moist, etc.

 

You could end up with a lot of control, but you'd then have to play with things to figure out what works the best.  And we'd be on our own with all of that because none of the recipes you'd find would be tailored for that kind of setup.


But again, these smokers work pretty well right out of the box, or with some simple modifications.  So playing with all of this is something I'd be doing, in great part, just because it's a fun part of the "hobby", not because it's necessary to get good smoked food.  The last pulled pork and the last batch of smoked pecans that I did came out just great with things just as they already are.  So I have to admit that this whole exercise would be mostly just smoker-nerdism!

 

Quote:
Originally Posted by Dr K View Post


My cables and probes clip/lay/hang/suspend from the rack above the meat so no obstruction. I made rtv silicone pucks, the clips the probes came with are clipped on the underside of the rack above the food. Use wooden clothes pins. Get probes/cables away from your food that aren't in the food. Dont let finding a home for your chamber probes be your demise.
-Kurt

Excellent points, and I like the high-temp RTV pucks!

 

You really don't need a bunch of wires and probes interfering with the use of the smoker.  That looks like an easy way to move things around when you need to, yet keep them in place.

 

Quote:
Originally Posted by TallBM View Post
 

 

Thanks for posting your solution.  Maybe i can take a bigger champagne cork and put the little probe through it and pull through some excess chord so I can then let it dangle through a rack above meat.  I will try and mimic your design with a cork and see what happens. 

 

So far I've tried to utilize a little flue tape and a small stainless steel hook to try and rig up a hanging mechanism for my PID smoker probe.  The squeeze clip is just not working out and is barely small enough for the probe to fit in it.   The PID probe is the small and doesn't want to cooperate so well with my make shift hook addition. I will look into the alligator clips as well. Thank goodness the maverick probe has no issues.

The probes I bought to use for my proposed project came from Auberins.

 

I got all type K thermocouples because that's the kind of inputs I had available for my controller.  I'll have to use type K thermocouple extension wire for them, though, which is an issue, but I have a bunch of that on hand now.  But the point is that I found three different types of probes.

 

A meat probe, which is just like most meat probes with the probe tube bent over at a 90° angle and a sharp point on the end.

 

Air probes that have alligator clips already on them so I can move them around to monitor various points inside of the smoker.

 

A bulkhead-mount probe that I'll mount through the smoker wall to be the main sensor for the PID control of the smoker temperature.

 

As with the OEM setup, I'll likely put that sensor in a position above the heating element and not too far up from it so that it shows me a "worst case" highest temperature for fast response and greatest safety.  I can log the temperature at the other two alligator clip probes and even work them into the control algorithm if I want, too.  Being able to see how far the alligator clip probes are from the main sensor can be used to control the duty cycle of the circulating fan, too.

 

It should be interesting to see how uneven the temperatures are without the fan operating and then see how much that can be helped and how much fan operation is needed to achieve that.

 

 

When I did the last pork butt, I again placed the smoker's meat probe below the butt, hanging in paper clips from the rack about an inch below the butt.  And I wrote down what that temperature read at various points in the run.  I only inserted the probe into the meat after it had cooked for quite some time so I was sure the outside was pasteurized, and then, only after probing with a separate meat thermometer showed that the IT was getting high enough to warrant constant surveillance.  So I do have the data for most of the run.

 

But I can only go by the smoker's own probe to know what the smoker's air temperature was supposed to be at all of those times.  So I'd just have to assume that it was holding the set temperature.  Which it may well have been.  The butt came out great for whatever that's worth.  ;)

 

Having some separate, independent probes that I can place as I wish should prove informative.  It would be neat to make a run without the fan stirring, and then try to keep everything the same, but use the stirring fan, and see how a probe placed near the meat responds in both cases.  But there are a lot of uncontrolled variables in such an experiment.  Still, it'd be fun.

 

I'm waiting for good weather here to take on this project because I'll need to run cabling for the probes to where I plan to have the controller.  And I'll need to take the smoker's back off and do some kludging for the fan and the probes as well as to bring out the power feed for the heating element so I can control it.  And I'd like to do that all when I'll have good weather for it.

 

So for now, I'm just accumulating parts and pieces and trying to think of how to do it best.

post #54 of 68
Thread Starter 
Quote:
Originally Posted by Sigmo View Post
 

That's right.


The way I am thinking about all of this is that the stirring/circulating of the air within the smoker is independent of the air flow through the smoker.

 

So, as TallBM points out in a later post, what we want (for circulating the air within the smoker) is a draft inducer type fan which stirs the air within the smoker itself, but which does not directly affect the flow of air through the smoker.  This is exactly the type of fan I've got and am considering installing into my MES 40.

 

The airflow through the smoker (the "draft", if you will) can then remain the same as it always was, being driven entirely by the convection (warm, lower-density air rising due to its buoyancy with respect to cooler, denser air).  Or, a separate forced-draft system can be used to force air through the smoker if desired/needed.

 

I think it's best to think of these two air-flows as being separate, and separately controlled or adjusted.

 

Quote:

 

That fan is very much like the one I got to try in my smoker.  I got a used fan meant for a convection oven.

 

(Darn how I hate that term:  "Convection Oven")!

 

Convection is the effect where air circulates due to differences in density, usually due to temperature differences.  As you heat air up, it wants to expand.  If the pressure is kept the same, it "swells up" if you will.  Naturally, when the air expands, its density goes down because the same number of molecules are now occupying more space.  So any given volume has less molecules and therefore less mass.  This is why a hot air balloon has lift or buoyancy.

 

Anyhow, it is this effect that causes convection.

 

But in a "convection oven", a fan is used to stir the air, NOT convection!  So the terminology is completely backwards and counterproductive, creating more confusion among people, which is a real crime IMO.  Whoever coined the term and applied it to a fan-forced oven should be ashamed of themselves.

 

Anyhow, I got a used fan from a "convection oven".  They're designed for just the kind of use we're proposing here.  The design uses a long shaft to separate the "hot end" (the fan and end of the shaft that is inside of the oven or smoker) from the "cool end" (the end where the bearings and motor are - outside of the oven or smoker).

 

There is also a separate, smaller set of fan blades back near the motor and bearings to help keep it even cooler and to draw heat that travels down the shaft out of the shaft before it enters the front set of bearings.  This all helps allow such a fan to last a long time despite the main fan blades being inside of a very hot oven.

 

I need to drill a hole through both the inside and outside layers of the smoker body, and through the insulation between those layers.  I want the hole to be small so that I don't create a puncture in the oven and an unwanted path for airflow into or out of the oven.  But I also don't want the shaft to rub on the inside of the holes, so that's a tradeoff.  It'll never be perfect.  I also need to build an enclosure around the fan motor to protect it from the elements and to provide a grounded safety "cage" around the open electrical contacts on my fan's motor.  But I do want the fan motor to be able to stay cool, so I may put some ventilation openings on the bottom of its enclosure, and make it out of aluminum for best heat transfer to the outside.

 

The power wiring for this fan will enter this safety/protection enclosure through a normal electrical box fitting or conduit gland bushing, etc.  Electrical safety is a concern as is physical protection of the motor.

 

I'm still considering the best placement of the little stirring fan.  I want it to blow air over the heating element of the smoker to some degree and stir the entire cabinet as well as possible.  We'll never have the kind of fancy airflow control like what is mentioned in that article you linked to, but I'm hoping it can be made considerably better than what I have right now.

 

I'd also prefer to place some kind of protective screen over the fan blades inside of the smoker to prevent accidental contact with them either by food or my fingers!  The placement of the little fan will need to be such that it doesn't interfere with the grates, etc., too.

 

I also think I may set up my control system to cycle the fan on and off rather than leaving it on 100% of the time.  In my home "convection oven", the fan switches on and off.  It may cycle on and off with power to a heating element that surrounds the fan, but in any case, it's not on all of the time.   It cycles frequently enough, though, that it probably does keep the air well stirred.

 

It may be that running it 100% of the time is too much, drying things out or making things cook too rapidly.  But in any case, having the ability to adjust (or have the controller adjust) the fan's duty cycle will let me play with that to get good stirring without having it be too much.  I think there are good reasons for not directly controlling its speed, but instead cycling it on and off.  And since that's easy enough to do, I plan on doing it that way.  As that article points out, the hot air can be made to sweep the cold air out from around the "product" and then left there for its heat to soak in for a while, then stirred again, etc.

 

One of the advertising sites I see for a manufacturer of these commercial smokehouses uses a set of dampers operated by a motor drive, that constantly move to make the "breakpoint" they mention move from place to place within the smokehouse.  They make the same point about sweeping the cool air away from the product, replacing it with the heated air, then letting the heat from that hot air soak into the product in that particular place while the smokehouse moves the breakpoint on to another place within the cooking chamber.


In our case, the chamber is small (like my home convection oven), so simply cycling the fan on and off probably stirs the air within the whole volume all at once, then, while the fan is off, you get that soaking-in phase.  I sort of get the feeling that they want to periodically stir the air to displace the layer of cold air that builds up around the "product", and replace it with hot air, but then they let it rest that way for a short time, then repeat that process.  Perhaps this gives less drying of the product yet achieves the even, faster cooking.  So I do think this is something to consider.

 

My hope is to get even cooking and smoke throughout the whole chamber regardless of how I load the "product" in.  Of course nothing is perfect, and I think it'll still be wise to arrange chunks of "product" in ways that lend themselves to good airflow around and between them to help keep things even.  But having a fan stirring the mix every so often should be a LOT better than just letting the air sit stagnant in the smoker.

 

 

Of course, now we get to the other airflow.  That's the air flowing through the smoker.

 

My feeling is that it will always be beneficial to be able to control that airflow separately from the stirring airflow.  And we'll have that by using a stirring fan as you've shown in your pictures above.

 

I figure the actual "convection" or "draft" will still suffice to let us use our mailbox type smoke generators.  The smoke generator won't even know if the stirring fan is on or off.  It'll behave, and the draft will be the same as it always has been.

 

But I'm not currently using a mailbox mod.  I just put an AMNPS inside the smoker, and have the inside ducting/baffling set up to draw air over the AMNPS by convection up and out of the vent at the top of the smoker.

 

I won't be able to do that once I have the stirring fan in place. At least not without some kind of modification.  I think the best will be to move the AMNPS outside of the smoker, into a mailbox mod setup, so that the airflow over the pellets will be independent of the air movement inside of the smoker.  So that will all have to happen at the same time as my installation of the stirring fan.

 

I guess I could do something to shield the AMNPS from the blowing of the stirring fan, and maybe continue to use it inside of the smoker.  But there are other good reasons to move the smoke generator completely outside of the smoker, too, and I've been planning on doing a mailbox mod anyhow, so I'll likely go that route ultimately.

 

Now, we also get to the idea of using a fan to force or regulate the airflow through the smoker.  And, perhaps a separate fan or way to regulate the combustion air over our burning wood chips or pellets, etc.  you could end up with three fans if you wanted to control all three air flows separately!

 

But simply adjusting the position of the damper at the top vent of the smoker, and playing with the positions and sizes of the air inlet openings in a mailbox will still work just as it does in a non-stirred smoker.  So actively controlling the draft and combustion air can be played with as separate projects.

 

 

I tend to think that having control over all of that would be handy, though.  For doing jerky, for example, one might run the stirring fan constantly, and force more air through the smoker than normal to aid in drying it during the later phases of the process.  Yet we'd want to keep the smoke density at some ideal level the whole time, so having independent control of all three air flows could come in handy there.  Or for crisping the skin on a turkey or chicken, we might want to do the same kind of thing.  On the other hand, for a lot of other smoking, we may not want so much air flow through the smoker so that things stay more moist, etc.

 

You could end up with a lot of control, but you'd then have to play with things to figure out what works the best.  And we'd be on our own with all of that because none of the recipes you'd find would be tailored for that kind of setup.


But again, these smokers work pretty well right out of the box, or with some simple modifications.  So playing with all of this is something I'd be doing, in great part, just because it's a fun part of the "hobby", not because it's necessary to get good smoked food.  The last pulled pork and the last batch of smoked pecans that I did came out just great with things just as they already are.  So I have to admit that this whole exercise would be mostly just smoker-nerdism!

 

Excellent points, and I like the high-temp RTV pucks!

 

You really don't need a bunch of wires and probes interfering with the use of the smoker.  That looks like an easy way to move things around when you need to, yet keep them in place.

 

The probes I bought to use for my proposed project came from Auberins.

 

I got all type K thermocouples because that's the kind of inputs I had available for my controller.  I'll have to use type K thermocouple extension wire for them, though, which is an issue, but I have a bunch of that on hand now.  But the point is that I found three different types of probes.

 

A meat probe, which is just like most meat probes with the probe tube bent over at a 90° angle and a sharp point on the end.

 

Air probes that have alligator clips already on them so I can move them around to monitor various points inside of the smoker.

 

A bulkhead-mount probe that I'll mount through the smoker wall to be the main sensor for the PID control of the smoker temperature.

 

As with the OEM setup, I'll likely put that sensor in a position above the heating element and not too far up from it so that it shows me a "worst case" highest temperature for fast response and greatest safety.  I can log the temperature at the other two alligator clip probes and even work them into the control algorithm if I want, too.  Being able to see how far the alligator clip probes are from the main sensor can be used to control the duty cycle of the circulating fan, too.

 

It should be interesting to see how uneven the temperatures are without the fan operating and then see how much that can be helped and how much fan operation is needed to achieve that.

 

 

When I did the last pork butt, I again placed the smoker's meat probe below the butt, hanging in paper clips from the rack about an inch below the butt.  And I wrote down what that temperature read at various points in the run.  I only inserted the probe into the meat after it had cooked for quite some time so I was sure the outside was pasteurized, and then, only after probing with a separate meat thermometer showed that the IT was getting high enough to warrant constant surveillance.  So I do have the data for most of the run.

 

But I can only go by the smoker's own probe to know what the smoker's air temperature was supposed to be at all of those times.  So I'd just have to assume that it was holding the set temperature.  Which it may well have been.  The butt came out great for whatever that's worth.  ;)

 

Having some separate, independent probes that I can place as I wish should prove informative.  It would be neat to make a run without the fan stirring, and then try to keep everything the same, but use the stirring fan, and see how a probe placed near the meat responds in both cases.  But there are a lot of uncontrolled variables in such an experiment.  Still, it'd be fun.

 

I'm waiting for good weather here to take on this project because I'll need to run cabling for the probes to where I plan to have the controller.  And I'll need to take the smoker's back off and do some kludging for the fan and the probes as well as to bring out the power feed for the heating element so I can control it.  And I'd like to do that all when I'll have good weather for it.

 

So for now, I'm just accumulating parts and pieces and trying to think of how to do it best.

 

Sigmo you posted the exact kind of info I was looking for. 

For my fan mod I have bought a "convection" oven motor and fan blade like you have done.

Also I purchased the following fan controller so I could wire it in and go from Zero circulation to the Max circulation or anywhere in between.  I think I will take a page out of the Traeger pellet grill smoking book and turn the fan to a LOW constant RPM so I get continuous stirring but hopefully slow enough to remove cool air and still allow heat from hot air to soak into the meat.  Only playing around will let me know but as you allude to, things work pretty well as they are with no fan so I think just adding a little stirring will go a long way and I have the option to go hardcore stirring for jerky!

Fan Speed Controller I bought and handles a max of 15A over 120V:

https://www.amazon.com/gp/product/B01IO5QO7U/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1

 

I have the mailbox mod so no issue with the air flow to the smoke generator and I believe the draft from the heat of the element will still pull air with no issue. I"m just going to live with my current vent setup so here is a breakdown of all 3 of my air flows:

 

  1. Breakpoint and Vent - I'm living with what is there, it seems to be OK and I think it will do well enough
  2. Draft into smoker - pulled from heat of element through my mailbox mod which will also suck the smoke in as it does today so no changes from my current setup there
  3. Stirring - Frigidaire 316136300 Range/Stove/Oven Fan Motor  and a fan blade for it.  I plan to drill into the box and attach from the outside as you mention.  Placement is still up in the air but I'm thinking in the back and out of the way would be great and also putting perpendicular to the Draft from the mailbox mod would be wise so that I don't chance blowing that draft back or interrupting it much at higher fan speeds for jerky and such.

 

As for probes my current PID on my Gen2 build came with the box mount type probe so it is small and get's blocked easily.  I'm working on getting it setup to be easily moved.  This smoker is may experimental smoker I'm giving away to my parents after I finish running it through it's paces to ensure it is good to go.

The probes for MY Gen1 smoker that I will be modding are all Hybrid probs (at least 3 of the 4 probes are).  But like you I am still gathering parts for that smoker overhaul as the HeaterMeter/LinkMeter PCB boards are on back order and should be in over the next couple of weeks. I still need to figure out a project box for that setup as well but I figure I would wire it up into a simple Gladware container and then understand the requirements for the project box after that :)

 

Thanks for the input and please keep us all posted on your fan mods and adventures.  I will surely do the same :)

post #55 of 68
Quote:
Originally Posted by TallBM View Post
 

 

Sigmo you posted the exact kind of info I was looking for. 

For my fan mod I have bought a "convection" oven motor and fan blade like you have done.

Also I purchased the following fan controller so I could wire it in and go from Zero circulation to the Max circulation or anywhere in between.  I think I will take a page out of the Traeger pellet grill smoking book and turn the fan to a LOW constant RPM so I get continuous stirring but hopefully slow enough to remove cool air and still allow heat from hot air to soak into the meat.  Only playing around will let me know but as you allude to, things work pretty well as they are with no fan so I think just adding a little stirring will go a long way and I have the option to go hardcore stirring for jerky!

Fan Speed Controller I bought and handles a max of 15A over 120V:

https://www.amazon.com/gp/product/B01IO5QO7U/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1

 

I have the mailbox mod so no issue with the air flow to the smoke generator and I believe the draft from the heat of the element will still pull air with no issue. I"m just going to live with my current vent setup so here is a breakdown of all 3 of my air flows:

 

  1. Breakpoint and Vent - I'm living with what is there, it seems to be OK and I think it will do well enough
  2. Draft into smoker - pulled from heat of element through my mailbox mod which will also suck the smoke in as it does today so no changes from my current setup there
  3. Stirring - Frigidaire 316136300 Range/Stove/Oven Fan Motor  and a fan blade for it.  I plan to drill into the box and attach from the outside as you mention.  Placement is still up in the air but I'm thinking in the back and out of the way would be great and also putting perpendicular to the Draft from the mailbox mod would be wise so that I don't chance blowing that draft back or interrupting it much at higher fan speeds for jerky and such.

 

As for probes my current PID on my Gen2 build came with the box mount type probe so it is small and get's blocked easily.  I'm working on getting it setup to be easily moved.  This smoker is may experimental smoker I'm giving away to my parents after I finish running it through it's paces to ensure it is good to go.

The probes for MY Gen1 smoker that I will be modding are all Hybrid probs (at least 3 of the 4 probes are).  But like you I am still gathering parts for that smoker overhaul as the HeaterMeter/LinkMeter PCB boards are on back order and should be in over the next couple of weeks. I still need to figure out a project box for that setup as well but I figure I would wire it up into a simple Gladware container and then understand the requirements for the project box after that :)

 

Thanks for the input and please keep us all posted on your fan mods and adventures.  I will surely do the same :)


That looks excellent.

 

That fan is virtually identical to the one I got.  I think it should work very well.

 

I'm torn between adjusting the speed of the fan versus cycling it on and off.  I could do either with the controller system I'm going to use depending on the type of output I choose.  On the one hand, having the fan run constantly at a low speed seems like it would keep things more evenly stirred and be more consistent.

 

But on the other hand, running it full blast, but only intermittently might have some advantages to consider:

 

1.  With the fan running full bore, you'd get a more vigorous blast of wind inside the chamber, so it would "break through" any stratification and force its way around more difficult paths better.  So that might give better "reach" into the corners, nooks, and crannies.

 

2.  If the bearings gum up a bit, starting the fan full bore will tend to break past that crusty-bearing resistance and allow the fan to start more reliably after things get more gummed up with smoke residue.

 

3.  There may be some method to their madness in the commercial convection ovens where they do seem to run the fan full blast, but intermittently.  Perhaps the "blast and soak" has some cooking advantages over the more gentle-continuous stirring of the air.  I tend to think that it may be good to have high air flow to better "scour" the cool air away from the product every so often lest we get zones of stratified air that are hard to penetrate with a gentler blowing action.

 

I've been amazed at how badly the air in laboratory ovens stratifies.  Having huge temperature differentials over distances of only a few inches points out how resistant these stratified zones must be to stirring from normal convection.  They're sort of like the stark layers you get with a temperature inversion.   Still, any active stirring has got to be a LOT better than just letting things be stagnant and stratified.  I just like the idea of really blasting it every so often to break through and destroy any of these "barriers" that might develop.

 

 

The problem becomes how to achieve this intermittent "full-on/full-off" mode without using a fancy programmable controller or microcontroller, etc.  For the major manufacturers of convection ovens or smokehouses, it's no problem, and is likely even cheaper to implement than a variable speed control.  In my home convection oven, I can hear a mechanical relay kick on and off as the stirring fan comes on and off.  So since they've already got a microcontroller running everything, it's cheap and easy for them to just add a cheap mechanical relay and use a digital output on the controller to run it.  So they may be doing it just because they're being cheap!

 

Also, they may be cycling the fan on and off simply because it's cheap and easy to just wire the fan in parallel with the circular heating element that surrounds that fan.  They just cycle the heater on and off as needed, and the fan just goes along for the ride!

 

So I don't really know if they're cycling it full-on/full-off on purpose because they think it will work better that way, or if they're doing it that way just because that's a cheaper option for them than using a variable speed setup.  Beats me!

 

Again, I can see pros and cons to doing it both ways, so I'll be interested to hear how the variable speed control works for you.  That looks like a good unit, and the price is right, too!  It will make it easy to experiment and adjust things easily to get what you want.  And I agree that it may well be that just a bit of gentle stirring will likely make a big difference in uniformity without drying out the meat too quickly.  But you'll have the option to blast it hard for jerky or crisping, etc. 

 

 

You make a good point about not letting the stirring fan accidentally blast air towards the air inlet, thus, perhaps, causing backwards flow or reduced draft, etc.  The placement of the fan and maybe some kind of baffling will need to be considered to keep the fan from affecting the "draft" through the system!  Ideally, the stirring won't affect the draft at all.  But it would be all too easy to get some kind of accidental pulling or pushing of the draft air!  So we'll have to be careful with that, for sure!  And that might be more of an issue when the fan is running full bore, too.  So that's something I'll need to watch out for.

 

The way the blades on mine look (and I think it'll be identical to yours), it must pull air inwards at the center of the blade disk.  Then it slings it outwards in all directions.

 

This works great with the circular heating element that surrounds the fan in my actual convection oven.  And in our smokers, I think it might work very well, too.  But since air will go out in all directions from the fan when it's on, some of that might end up aimed right at the normal air inlet to the smoker.  So some kind of baffle might need to be installed so that the inlet port doesn't see any increased (or decreased) pressure when the fan is running.  Ideally, the inlet port will see the "average" air pressure inside of the smoker so it will draft normally with or without the fan running.

 

 

You might not need to worry as much about your current PID's sensor being "blocked" once you're running the stirring fan.  Ideally, having things stirred will give us better control since the controller's sensor will "see" a better representation of the overall temperature in the smoker.  You still want things to be safe with the fan turned off, of course.  So I plan to mount my "main" sensor more or less where the manufacturer's sensor is located.  But I anticipate better control with the fan stirring taking place.  I just want it to be safe if the fan is off on purpose or fails for some reason.

 

 

There's a lot to be considered in all of this!

 

 

We'll both have to keep posting as we get further along with these projects so we can share our thoughts and experiences.  This forum is great.  :)

post #56 of 68
Thread Starter 

Sigmo we have some fun times ahead of us for sure.  I have a feeling it will work out well.  I believe the Traeger pellet gril has a fan that runs like 2.5 RPM for their smokers.  If that stirs and keeps their pellets going then I"m sure anything we do will be icing on the cake :)

post #57 of 68
Quote:
Originally Posted by TallBM View Post
 

Sigmo we have some fun times ahead of us for sure.  I have a feeling it will work out well.  I believe the Traeger pellet gril has a fan that runs like 2.5 RPM for their smokers.  If that stirs and keeps their pellets going then I"m sure anything we do will be icing on the cake :)

 

You're right!

 

And you bring up another point, too.  A stirring fan also "stokes" the pellets.  Since I have had to resort to heroic measures to keep pellets burning at my elevation, a bit of extra airflow over a smoke generator that's inside of the smoker might not be a bad thing for me.  But it would have to be very gentle or else it'd be way too much of a good thing!  I can see how a very slow stirring fan would help with uniformity of temperature and smoke and also help keep pellets burning reliably.

 

I can't wait for a long stretch of good weather when I have some time off to pursue this project further.  I guess I can run some of the wiring ahead of time, but I've had a lot on my plate (besides great smoked meat) lately, and just haven't gotten around to all of that.

 

Since I'm going to use a fancy programmable automation controller for this, and since that same controller will be doing other chores around the house, I will keep it in an office room.  But that means that the thermocouple extension wire as well as other sensor cables and control wiring will need to be run from that room out to an outdoor connection box at the back porch where the smoker lives.  I've got the wire and connectors, etc.  But I think I'll run plastic conduit over the wiring route so I can pull additional wires as necessary.  This will all be low voltage signals.


Then, out at the back porch, I'll have another box with any solid state relays and other high voltage goodies needed at that end.  I'll set it up so that I can just unplug one 120V power cord to kill all of the HV stuff in the system.  The heater and fan of the modified smoker will simply plug into receptacles on that interface box at that end.

 

This controller system has a nice, free MMI software and the control software is also free.  So I can then interact with the smoker (or anything on that controller) from any PC connected to our home network.  That will allow for control and data logging, etc. for not only the smoker, but other things around the house.  I'm doing it this way simply because I already have the controller gear and I work with this stuff at my job, so I'm comfortable with it.  It wouldn't be a very practical way of approaching this for most people.

 

What would be better, cheaper, and more useful for more people would be to set up an Arduino or Raspberry Pi type system to do all of this.  But I'm just not that familiar with all of that, so I'm taking the easy way out for me at this point.  Maybe someday I'll find a lot of time for playing with one of those other, cheaper systems, and then it would be fun to come up with a fancy system that a lot of people could replicate for their own systems.  Heck, if I looked around, I'd probably find that this has already been done a number of times, actually!


But what fun is that?  ;)

 

I really want to play with it this way because I could use more experience programming the MMI in particular on this system because that will help me at work.  So it's very impractical, but should work for my purposes.  The only things that will likely come of it of any use to most of the rest of us on here is the data I'll gather about what ends up working and what doesn't.

 

This is a good "prototyping" kind of setup for me because of the extreme ease of programming for both the control system and its MMI (man machine interface).  I can make program changes in a few minutes and be running them immediately.  That's what I need because I NEVER think of everything on the first revision of ANY program. :)

 

Trial and error and many iterations.  That's what works for me.  :)

post #58 of 68
@Sigmo does the fan controller have a three prong plug so it's grounded? I couldn't tell. If it does I guess it would run mes heating elements being 120v 15A = 1,800W. Just wondering if it would work. If it would then you could turn it on full to preheat and switch to variable without adjusting the dial. As well as bumping the heat up on full for a minute then switching back to variable during a smoke without touching the dial. Keeping my eyes open for when my electronics fail. I may try a rheostat before a PID. I like that switch.
-Kurt
post #59 of 68
Thread Starter 
Quote:
Originally Posted by Sigmo View Post

 

What would be better, cheaper, and more useful for more people would be to set up an Arduino or Raspberry Pi type system to do all of this.  But I'm just not that familiar with all of that, so I'm taking the easy way out for me at this point.  Maybe someday I'll find a lot of time for playing with one of those other, cheaper systems, and then it would be fun to come up with a fancy system that a lot of people could replicate for their own systems.  Heck, if I looked around, I'd probably find that this has already been done a number of times, actually!

I'm going the the HeaterMeter/LinkMeter route (Raspberry Pi).  It will come loaded with the open source (free and freely available to modify) software pre-loaded.

I plan to do a step by step of setting it up.  Additionally I have no problem writing software to update, enhance, or modify what I can or want with the system.  I don't plan on doing this or doing an extensive amount of software additions but I have a feeling I may add some scripts or two if/when the time comes.  The system seems to be setup for that.

 

I plan to post a step by step once I do it.  Just gotta wait for the back ordered stuff to come and some time to do it all :)

post #60 of 68
Quote:
Originally Posted by Dr K View Post

@Sigmo does the fan controller have a three prong plug so it's grounded? I couldn't tell. If it does I guess it would run mes heating elements being 120v 15A = 1,800W. Just wondering if it would work. If it would then you could turn it on full to preheat and switch to variable without adjusting the dial. As well as bumping the heat up on full for a minute then switching back to variable during a smoke without touching the dial. Keeping my eyes open for when my electronics fail. I may try a rheostat before a PID. I like that switch.
-Kurt

Hi there.

 

I'm not sure which controller you're referring to.

 

What I'm going to be using will be based on the Opto 22 SNAP-PAC line of controllers in a SNAP-IT rack that I've got laying around, using various I/O modules as needed.  And the wiring to the smoker's heating element and the fan will be connected to a box that I'll be building.  So in this case, I will install normal 3-Prong receptacles in that interface box when I build it.   I may use 20 Amp receptacles just to allow for the possibility of higher power devices at some point, but all of the receptacles will be grounded, having their ground contacts wired to the main cable that brings power out to that interface box.

 

The fan I've got does have a spade type "male" for grounding as well as similar spades for the hot and neutral power wiring to the motor windings themselves.  The way I plan to wire the MES is to have two separate three-wire (grounding) power cords coming out of the MES itself.  One will be for the fan, and the other will be for the heating element.  Both of those cables will provide a ground path to the chassis of the MES, so if either one (or both) is plugged in to a grounded receptacle, the chassis of the MES will be grounded.  My "interface box" will be grounded by the ground wire inside of its three-wire power cord, and any and all power receptacles on that box will carry that ground through their ground pins.

 

In my case, the way I'm envisioning it, since I'll have separate independent control over the fan and heating element, I could do what you're talking about and control the heater power and fan operation separately to get what I want during different parts of a smoke.

 

I can get SSRs that accept a 4-20mA or analog voltage signal and put out a phase-controlled variable output.  In that case, I could run the fan full blast or at some variable speed under the control of the controller.  But if I do that, and also want to use the fan in the "full-on/full-off" mode, and vary the duty cycle of the "full-on" periods, I would need to create that duty cycle control "by hand" in the program strategy.  But if I forego any variable-speed operation of the fan, I can use the controller's I/O Brain to implement what they call "TPO" (time period output).  When you use the TPO feature on a digital output, all you do is define the total time period somewhere in the program (strategy as they call it) and then tell it what percent "on" you want at any point in the strategy.  That percent on can be the output of one of the PID loops running on that I/O brain.  A bit of overkill, but a really easy, lazy way to get what I want.

 

I guess you could set things up so that you've got one of the analog-controlled SSRs that act like a "dimmer" based on a 4-20mA or analog voltage signal, and use an analog output module to provide that signal.  Then, you could simply wire that analog signal through the relay output contacts of another digital output module that was configured to be a TPO (time period output).

 

So you could set the fan's speed with the analog output, and then set the on-off duty cycle with the digital output.  That would let you have any kind of fan operation you might ever want!  The digital output module would need to have a dry-contact relay output for it to properly pass the 4-20mA or analog voltage signal, but I've got a few of their reed-relay output modules laying around that I got surplus a while back.  They come in handy for things like this.  Auber sells SSRs that act like dimmers, and accept an analog voltage input to control them.  You can find them on EBAY, too.

 

Now that I've written all of that, I'm thinking you may have been asking about that neat speed control that TallBM mentioned earlier.  I need to look it up again, but as I recall, it did have a grounded three-wire power cord, and its output receptacle was also the grounding type.  So you should be able to make sure the fan (and whole chassis of the smoker) is properly grounded.  I do think grounding these smokers is very important.  Anything with a metal cabinet, and used outdoors, or even in a garage, should be grounded for safety.

 

I can envision setting up the "Recipes" (as the Opto 22 people call what might be otherwise called a "macros") to do a pre-heat sequence.  And for that, as you say, it might be great to have the fan on full blast to get everything up to the desired starting temperature quickly and uniformly.  Then, when the actual cooking begins, you'd likely want to go easier on the stirring fan, depending on what you were cooking.

 

I'd be controlling the temperature via a PID loop the whole time, but depending on how that PID loop is tuned, it'd have the heater turned on pretty much full blast while preheating anyhow.  That's the nice thing about a PID loop.  It'll heat up to the setpoint as fast as possible, but shouldn't overshoot or "ring" much if any at all (if tuned correctly).  But tuning a PID loop can take a bit of tweaking.  Most PID Controllers that you buy as a separate gadget have an "auto-tune" mode, which, if done correctly, can get the tuning pretty darned good on one try.

 

I don't think I'd ever bother with a variable power "dimmer" kind of thing for the heater if I had a PID controller to use instead.  If you set the PID controller (or software) to a fast enough cycle time, the heating element will be turned on and off fast enough that for all purposes, you wouldn't be able to tell the difference between that and a dimmer (as far as smoothness of the control).  Most of these heating elements are fairly heavy and don't heat up or cool down all that fast.  So using a fairly short time period for the PID loop would make for very smooth heat control with very little cycling up and down of the temperature in the smoker.

 

The thing to remember about one of these speed control (dimmer) type units is that they're great for setting a fan speed or something like that, but for setting the temperature in a smoker, they'd be kind of a hassle because they're not really a temperature controller.  They don't know what the temperature in the smoker is.  So you'd have to "be the controller", adjusting the knob while watching a thermometer all of the time.  You really would want a thermostat or PID controller of some sort to make the system easy to use and forgiving of changes in sun, outdoor temperature, wind, rain, and the wetness and temperature of the meat you were cooking, too.  One of the things I love about the MES just as it came from the factory is the ability to just set the temperature and then not worry about it.

 

It really has spoiled me versus tending my charcoal smoker!

 

Quote:
Originally Posted by TallBM View Post
 

I'm going the the HeaterMeter/LinkMeter route (Raspberry Pi).  It will come loaded with the open source (free and freely available to modify) software pre-loaded.

I plan to do a step by step of setting it up.  Additionally I have no problem writing software to update, enhance, or modify what I can or want with the system.  I don't plan on doing this or doing an extensive amount of software additions but I have a feeling I may add some scripts or two if/when the time comes.  The system seems to be setup for that.

 

I plan to post a step by step once I do it.  Just gotta wait for the back ordered stuff to come and some time to do it all :)

 

Hey!  That looks like a nice way to go.  Lots of possibilities with all of that, and I like the remote radio link part of it, too.  That's more like what I was thinking would be a nice, practical way of implementing this!  So I'll be interested to see how this works out for you.  Plus, I should read up on that equipment.  I need to play with the Raspberry Pi system and become familiar with it and the Arduino stuff.  I have an Arduino experimenter's kit that I have yet to play with at all!  Just too many projects, always, I guess.  But I WILL eventually play with it.  There are so many possibilities with Arduino and Raspberry Pi that it's a shame not to become intimately familiar with it all.  So many projects come to mind, don't they?  :)

 

It looks like the page I landed on when I searched is aimed at controlling a fan or damper to control temperature in a charcoal burning system.  I thought about that quite a bit before I got the MES.  I still think that all has a lot of potential, too!  There were some aspects of my ECB smoker that really were kind of nice.  But the electric smoker has spoiled me and made me lazy, I guess, so I've gotten side-tracked into that for now.

 

It seems like modifying the program to run an electric heating element would be fairly straightforward, and if I took the time to read further, I'd probably find that this has already been done!

 

I'll post a step by step thread showing what I end up doing, too.  It won't be as useful as yours because of the rather obscure hardware I'll be using, but the measurements and observations about how things work inside of the smoker will hopefully be useful to everyone.

 

This will be fun, and especially so with several people going at it from slightly different directions and sharing their observations and hints!

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