Wild temperature swings normal? See graph

Ya but how was the chicken? All ovens temps swing heat is energe and it has to stop going up before it goes the other way. Be happy that the smoker controls it in stead of you having to watch over it all night adjusting the nob or putting more wood on to make it warmer. It looks to me that the meat temp. was steady and also you don't have to worry about it drying out.

This is a frequent topic, I'll have to do a search to find some old posts.

Good job charting the temps.

Until then....

Yup, in the smaller model, it's not unusual to see such a swing.

Butt...isn't there always a But, especially in BBQ. Ricky is right, how was the chicken? I think the success of the smoker speaks for itself.

You biggest issue is manufacturing. You won't get the same sophisticated controls I get in the 150 in the Smokette? Why? cost!

Stuart can certainly jump in here, but I believe that given the type of element used and the controls in that model (different ones for different models), that it doesn't control the fluctuations as closely as the more expensive models. You pay more you get the more controlled fluctuations.

When this has come up before, there is some time the assumption made that there wouldn't be temp flucs, even as large as this. As long as it always comes back to the temp we're all fine.

I'm sure others will join in, but that's my thought on the subject.

Smokin'

When I first got my Smokette I noticed the same thing and posted some questions about it. Finally, I realized that the product I was getting from the smoker was what I was after and realized how it got there didn't really matter. I think your chart though addresses the real issue. While the ambient temperature in the smoker rises and falls dramatically, the product (chicken) follows a nice slow steady climb without the rise and fall. After all, its all about low and slow and your chart shows the meat is doing its own thing despite the fluctuations. Just my two. Good luck with your new smoker, you won't be disappointed.
Richard

Geez,I'm sure glad my yardbirds can't read graphs.They thought they was in the perfect environment, and I didn't know to tell them different.

All kidding aside,I have the luxury of using what have been rated the top professional ovens tested ,'cause my bride is a pastry and bakin' kinda cook.Them folks actually measure stuff.

She even got ovens that proof stuff.Silly wimmen.

I occasionally stick a tater with a probe through it in there and watch it for an afternoon.

She just looks at me like I been playin' in the adult beverages again.

I tell her "I ain't got nothin' else to do,the CS is out back fixin' dinner".

It ain't near as accurate as my cd player,playin' Jerry Jeff Walker or Guy Clark,but it cost a bunch and it must know somethin' I don't.

It don't seem much different than the CS for swings and her cookin' tastes purty good.

I just put it down to magic and accept the finished product.

Steve H

I too had wild swings in the temperature when I first got the smokette. I was running swings of 90 degrees. So I called up Tony and he sent me another thermostat. With the new one, my swings were 55-60 degrees (about the same as what you are getting). While the product always tasted good, I was still concerned particularily at a hold temp. of 140 where the swing would be from 110 to 170. And in my case, the product was going down a few degrees at the bottom of the cycle. My concern about the holding temp. swing was that for a significant amount of time you are actually cooking the meat more and a significant amount of time where the meat is deep in the danger range.

So I saw an ad for a Pakstat I thermostat in Allied Kenco for $100 that guaranteed a range of plus or minus 5 degrees. I talked to the people at Pakstat and they agreed that their thermostat would work in this setting. I ordered it and installed it (you need to know a little about wiring and wiring diagrams to do this). Much to my amazement, however, the range with the pakstat was about the same as the original in the smokette. Now I hardly wanted to pay $100 plus shipping for that privelage. So I did some expermintation. Rather than attach the pakstat probe to the back wall, I just let the tip extend out into the interior about an inch. This caused the swing range to be reduced to about 15 degrees total-a vast improvement. I also tried it with a pork butt and got the swing down to 8 degrees-within the plus or minus 5 degrees specified by pakstat. I then put the original CS thermostat back in with the probe just dangling into the chamber about 1 inch and got the swing range down to about 30 degrees (without meat in the unit). Of course this was a reduction of about 50% in the swing range. And the swing would have been less if I would have had meat in the chamber.
Anyway I put the pakstat back in and built a little bracket that held the probe out from the wall about 3/4 of an inch and took out the bracked that CS supplied to secure the Probe. I also put screws in the holes and calked with high temp. calk.

I also did some other experminents by using two temp. probes-one within 1 inch of the pakstat probe and another in the middle front about 3/4 of an inch from the front door and about 5 inches above the fire box. I found out that the temp. in the front of the unit runs as high as 14 degrees above the back of the unit and as little as 4 or 5 degrees depending on the point in the cycle of "on and off" of the heating element. So the back of the unit is always trying to equalize to the front. In fact, I found out that by listening to the click on and off of the thermostat, and by recording the temperatures, the pakstat was actually cycling on and off at a plus or minus 1 degree range. But the total swing was about 8 degrees due to fact that the front is always warmer than the back and it is always in an equalization mode.

Now the folks at CS have always been wonderful. But I do disagree with them in the mounting of the probe. With the mounting of the probe in contact with the back wall(acutally having a bracket confining and forcing contact with the back wall) the proble is measuring the temp. of the back steel wall. In my opinion, it should be measuring the temp. of the air in the inside of the unit (and therefore the probe should be mounted so that the tip is out slightly from the wall). Because the steel wall is a mass substantially different from air, it is always substantially "behind" the air temperature of the interior. So while the heating unit has shut off at the pescribed temp. (the temp. of the wall) the interior of the unit is substantially higher in temperature. An it works the opposite on the downside. This causes the wide swing in the temperature in addition to the fact that the heating element produces more heat toward the front of the unit and is always in the process of equalizing out to the back.

Just my two cents and research results. At least my temperature with meat in the unit stays plus or minus 3 or 4 degrees. I'm not sure this changes the quality of the product, but at least I know the temperature is always close to what I set it at.

PS
One thing I found with the pakstat was that it does not have a off position. Now if you live in southern part of this country it does not make any difference since the ambient temperature is always above 35 degrees or so. But up here in the north country, if the temperature falls below 35 degrees, the thermostat cycles on (the range of the thermostat is about 35-275 degrees and is rated at 50-250). So I had to put a toggle switch in front of the thermosat to actually shut it off in temperatures below 35 degrees. You could do the same thing by unpluging it also.

MN Que, I'm sure you realized that voids any warranty, but sounds like you're apt to fix it yourself anyway.

So, now let's discuss not the fact that there is a fluctuation, but is there any impact?

Smokin

Ricky & SmokinOkie: You're quite right to focus on the result rather than the measurements - The bird was indeed cooked just fine; moist and tender. I still have a lot to read/practice/learn about seasoning and prep (rub flavors didn't make it into the meat), but it did get a good smoking.

I was just surprised by the temps and wanted to find out if it was normal. It sounds like my Smokette is working-as-designed, and in no way unique or defective. Happy to hear that.
I'm hoping to make repeatably-good BBQ, so recording the temperatures just seems like an easy thing to get a geek handle on. The more things I can hold constant, the less I have to guess at.

MN Que: Awesome post! I agree that a thermostat should operate on the air temperature rather than the metal wall temp, since hey, it's the air that cooks the goods. That has to explain a lot about the temperature spread.

I could be wrong, but the front wall is probably hotter because the smoke box fits snug against the back and leaves a gap at the front. In a no-draft closed environment, the hot air probably rises right up the front wall, heats it, and excites the front probe. I'd be curious to know if you get the same results if you do not slide the metal smoke tray all the way to the back -- leave it forward and let the door contact it to push it back.

One thing I've been wondering about is the slow heating cycles.. In 3 hours of smoking, the heater coil came on only three times -- the initial ramp-up, and two twenty-minute boosts later on. Would this also make the wood smoke in bursts rather than a nice steady burn?

I have to resist the urge to replace the thermostat with a thermocouple air probe, Solid State Relay and PID controller. An insulated oven like this, with a proportional heating coil should be able to hold within a few degrees easy. But like everyone else said.. does it really matter.

Thanks for the replies!

Steve, MC Que

I'd certainly take the time to send an email to Stuart at Cookshack. I believe he is always tinkering with the machines and you never know when someone can come up with a good idea. He can also talk about the technical experience with the smoker over the years.

Smokin'

All I know is I just cooked a Butt and a briskett at the same time yesterday pulled the briskett at 200 D. last night and pulled the butt at 200 D. about a hour ago and they cooked just fine and on time. Smoking is the science not the smoker.

I think most old cookers would opine that this is truly relavent if you were cooking a material that behaved with consistency.

They might pay closer attention if cooking a skinless,boneless chicken breast half of 4 ounces.

I think Donna once explained that her family designed the CS to cook briskets and swings really are not that critical.

Some of those briskets behave so differently,you'd think they weren't even from a cow.

Just my $0.02.

I agree the brisket cooked quicker than the others may be because I had a butt in with it.I think we had a topic about this and it was a good topic about why a loaded smoker seems to cook faster.

Smokin:

That warranty was voided after the first week I had the smokette. While the Smokette is a good appliance it, like most things I buy, are not perfected to the level I like. And with all kinds of tools and even a welder and my natural engineering talents, my toys get perfected.

With respect to contacting Stuart-Been there- Done that. Sent a detail report of my analysis to Stuart and Tony at CS about 6 months ago.


An additional thought I had though was the question "Is a variation in temperature a positive element in Q cooking". In other words, could this temperature swing be a good thing in terms of enhancing cooked meat quality and flavor. Do you know of anyone that has done research on this?

Also, with respect to location of the probe, I forgot to mention that my Jenn-aire oven has the probe set out from the wall about 1 inch. It produces a swing of about 30 degrees.

Regarding cooking times with more product(s) in the unit, it would seem logical to me that the faster cooking times are due to the increased humidity in the unit (the steam effect) due to the larger mass of product (including water) and the contiously limited CS vents and drain holes.

MN Que

In reading the above posts and thinking through the issues that could result from "perfect" temp control, it occurs to me that achieving this perfection may actually be counter productive. As most all have stated, the results from the smokers are great and can be reached with relative ease. Why? Because it is an electric smoker and it removes the unpredictable nature of a fire and replaces it with predictable heating cycles of a thermostat. With that said, what makes the smokette different from your indoor oven is the ability to produce (believe it or not) smoke. Whether by Cookshack design or coincidence I believe that the longer cycle times lend themselves to allowing more time to actually heat the wood to the point of producing smoke. If the oven was controlled to within +-5 degrees for example, it is probable that the heating element would not be on long enough to cause the wood to burn. After all its only a few cubic feet and we're trying to achieve an average temp of about 225. Heating from 220 to 225 wouldn't take that long.

Anyway, its just a therory and besides I'm happy with the results as is.

Richard

Howdy, RPM.

They are advertising available passes for the coming midnight launch of the shuttle.

Of course,if it is a clear night ,you can probably see it from Hotlanta.

Not sure if that gives the same thrill as having your frosty beverage shake ,when it comes off the pad.

Especially when you are sitting in your lawn chair,just across the water.

PrestonD can probably lend some tips to viewing.

I like your whole post ,except knowing your your cooker leaves you with a pretty predictable fire behavior- with enough experience.

Come on down and see us.

Hi All,

Sorry for long post here...

This has been a really good post for lurking on...being a former instrumentation and controls guy at Kennedy Space Center I enjoyed some of the comments noted above. Great graphing and great comments by all!

The PID controller that Steve had mentioned with a temperature probe strategically placed inside the unit could address the temperature swings - the integral setting of the controller could handle the time aspect of the length of the temperature cycles and the angle of slope could be addressed by the derivative setting. All parameters could be tuned in the system with the PID controller to dampen out the oscillations. It would add about $300 rough estimate to the cost of the smokette. Is that really worth it? If you are a geek like me...

The smokette has a small volume with appreciable gain added to the process variable (temperature) when the heater comes on and that might be more difficult to control with an on/off controller such as a thermostat. But I do think there can be a way for more accurate control of the heater than the swings that are reported, but again you don't want the heater cycling off and on every minute or so as the thermostat might not be able to handle such a duty cycle. I am not familiar with the thermostat design used in the smokette, a more expensive thermostat might do the trick - I don't know.

I think the most important graph that is shown above is the internal meat temperature...that is a pleasant upward moving stable slope. And that speaks volume of the end results and is really the most important variable.

because everyone is right in that the end product is what counts...you will need to do a cost benefits analysis on whether it is worth it to implement the new controller design... ha ha...

FYI, I will be soon adding a new page on my web site for information regarding digital thermometers (I have been discussing with the head of engineering at Taylor Instruments) and also will be adding another page in the future regarding the BBQ Data Acquisition and Telemetry System (BDATS for short) that I am designing. The system is comprised of a RS-232 serial interface analog input acquisition device that you connect to your PC and hook up to 4 temperature sensors to it. The cost of the data acquisition unit itself is very inexpensive and is $25 and available from Dataq, but the temperature sensors I am working out the design and costs of. Commercially available temperature sensors with the proper signal conditioning can be close to $100 or more so I am trying to use the Taylor thermometer probes as they can be had for $2.50 a unit directly from Taylor. I designed a signal conditioner circuit for the probe I just have to bench it and test...more to come on that in the future....

I must have missed a comment regarding shuttle launches...but there is no longer any passes provided for viewing the shuttle on KSC due to new enhanced security since 9/11. The best viewing is actually in Titusville on US 1 right across the Indian River from the space center. If you can see the Vehicle Assembly Building (VAB) from US 1 in Titusville you most likely will be able to see the launch pads.

Take care!
PrestonD

RPM: It's a very interesting question you bring up. Would a 'perfect' 200-degree flat-heat hold be appropriate for smoking, or do we want the 'long burn' surge from a red hot coil now and then to stoke the smoke. Hmmm!

I think holding the oven air at 200 would probably still demand that the coil be pretty warm -- perhaps warm enough to burn the wood right above it. Anyone know what a good smoke-point temperature for wood might be?

As for the cost of the PID controller, I buy them for all kinds of things, and they can be found for ~$50 on eBay, sometimes brand new. I have one for my espresso machine, one for my fridge.. magical things they are.

That said, it seems pretty presumptuous of me, a total BBQ noob, to be tinkering with a fine oven. That, and I've been expressly forbidden by the Other Chef. I'm content to keep measuring and revisit the issue next year after I have some results to compare it to.

More pretty graphs coming (just because I can), but with an increased interest in the meat temperatures. I've got a fresh pork butt that needs some probing. You know, for science. Thanks again for the thoughts.

Hi Steve,
The cost I am referring to includes the controller, sensor probe, signal conditioning and power supply. When you add that all up it gets pricey. And yes you can always shop around and go to surplus stores, eBay, etc. and get cheaper prices.

I did a search on eBay with PID controller and there are a few units at reasonable prices thats for sure!
Thanks!

PrestonD

Preston D., I'm very interested in your invention. Great idea! The remote sensor I'm using gives more frustration than useful data. If you develop some "BDAT for Dummies" instructions, I'll be happy to serve as a non-technical reviewer to help you refine them for the general market.

Steve H.

I think what will be of good interest is any graphs you build for the meat temps. One of the hard things for people to understand is the time it takes.

Certainly we've talked before and the "conventional" theory of Q is that the smoke won't penetrate past a few millimeters and only then until the meat reaches 140. So on your graph that's at the 139 min point

I've tracked mine (although not as close as yours) and it usually takes longer than that.

Interesting posts and responses. Always good to understand the concepts of smoke and temp control and the effect.

When you're workin on that Butt, watch for the "plateau" it will be interesting to see if the temps hold for a certain period and if in fact, they drop some.

Thanks for the work!

Smokin'

Let's see if anyone's heard this story before.. I put the 6lb pork butt in around noon, expecting a fine bbq sanwich for dinner. Eight hours later, my meat temp totally stalled at 165, and wouldn't budge! Flatline..



I started to doubt my thermometer probe, and opened the door to get a second reading from another. (That's the wild air temperature swing around 500 and 600 minutes.)

I'm sure it's no surprise to the seasoned folks here, but the butt waited until 7AM to reach 192.

Good thing I had not invited guests for dinner, eh?

Yep sounds like my first one.

aaahhhh....

Proof that there is INDEED a Butt Plateau.

Good graph...where's the rest of it?

did you keep the temp at 225 for the whole cook? It can definitely take 2 hrs+ per lb for butt... I usually boost the temp to 250 toward the second half of the cook, to get it out a bit faster. So yours taking 15+hrs makes sense if at 225 the whole time. Whn set at 250 I see the cooker temp rising to around 290 at its peak. the charting is fabulous, by the way...

SmokinOkie: Next time I'll not open the door and disturb The Force.. that way we'll have a proper scientific photo of the Plateau in action.

As for the graph above, there is no "rest of it". When it got to 295 at just past 1000 minutes, I pulled it.

woodburner: Thanks. I did leave the dial right at 225 the whole time. Next time I'll know to push it up a little toward the middle to get it over the hump.

The question for this weekend is.. does beef brisket have a Plateau?

Looks like it sat on the plateau from the 400min to 700 min point. Lot of time, but certainly expected.

Actually a lot of people will bump the temp up as butts are so fatty, they can actually handled a little higher temp.

And I just didn't look close enough to see the total time.

I know the answer about brisket, but we'll just let you have fun and report back later.

for later items, I think I'd like to copy your images to our server, so that we'll also have them with the forum. Would hate for them to disappear. When I get time, I'll just copy them over and change the links.
Smokin

The chart is interesting,but I wonder how many briskets would need to be charted to give as good a graph as a butt.

Briskets have a temperament all their own and don't seem to work as well against a standard.

drbbq had a pretty good,yet simple,post today.

drbbq Brisket Thoughts

Steve: I was gonna give me answer to your brisket question, but I wouldn't want to spill the beans if Smokin wanted to let you find out for yourself

Well, I think you'll find that the brisket tends to take a little less time, pound for pound, than the butts. Of course, depends on what cut o' meat you throw in there (as drbbq suggested). What are you cooking? Whole monster, or flat? Does it have lots of fat? Weight going in?