I had nothing to do this morning so I sat down with a pot of coffee for a few hours and did some testing on the DBS temp swing issue.
Here's my test criteria:
- DBS with circulation fan running. (no PID running)
- Tower had the water bowl (full of hot water) in it and all 12 racks that I have.
- Suspended the ET73 at the same height as the factory TC but horizontally in the centre of the tower.
- Vent half open.
- Target temp 200 F.
- Running both the main tower heater and the smoke generator (SG).
Here's my test data:
- When I turned everything on the temp was at 64 degrees.
- During warm up the ET73 read constantly 20 degrees higher than the SG display.
- ET73 hit 200 degrees in 21 minutes and SG display was at 180.
- SG display hit 200 degrees and ET73 was at 220.
- SG hit 200 degrees I could hear the tower element cut out.
- SG continued to climb to 207 degrees before ET73 began to drop. ET73 was at 225 degrees.
- As the temps dropped they were the same at 203 degrees.
- ET73 hit 200 degrees coming down and the SG display was at 203 degrees.
- SG display hit 200 degrees coming down and the ET73 was at 192 degrees.
- As soon as the SG display changed from 190 to 189 degrees you could hear the tower element cut in. The ET 73 was at 176 degrees.
- SG display dropped to 187 degrees before beginning to rise.
- ET73 dropped to 176 degrees before beginning to rise.
- Both ET73 and SG display were equal at 191 degrees while the temp was rising.
- ET 73 hit 200 degrees and SG display shows 196.
- SG display at 200 degrees I could hear the tower element cut out.
- 1 hour point of testing.
- SG display continued to rise to 205 degrees and ET73 showed 218 before it started to drop.
- As the temps dropped they were the same at 203 degrees.
- ET73 hit 200 degrees coming down and the SG display was at 203 degrees.
- SG display hit 200 degrees coming down and the ET73 was at 192 degrees.
- As soon as the SG display changed from 190 to 189 degrees you could hear the tower element cut in. The ET 73 was at 176 degrees.
- SG display dropped to 187 degrees before beginning to rise.
- ET73 dropped to 176 degrees before beginning to rise.
- Both ET73 and SG display were equal at 191 degrees while the temp was rising.
- ET 73 hit 200 degrees and SG display shows 196.
- SG display hit 200 degrees I could hear the tower element cut out.
- SG display continued to rise to 205 degrees and ET73 showed 217 before it started to drop.
- As the temps dropped they were the same at 203 degrees.
- ET73 hit 200 degrees coming down and the SG display was at 203 degrees.
- SG display hit 200 degrees coming down and the ET73 was at 192 degrees.
- As soon as the SG display changed from 190 to 189 degrees you could hear the tower element cut in. The ET 73 was at 176 degrees.
Thinking Through The Data
During the test the temp swing of the SG display was 187 degrees to 205 degrees. The temp swing displayed by the ET73 was 176 degrees to 218 degrees. Also during the test it came to mind that the temp I was measuring on the ET73 was the air temp at the same level as the factory TC mounted in the back of the cabinet and the temp that the factory TC was measuring was the temp of the metal in the back of the cabinet. Clearly the DBS was designed to shut off the heating element in the tower once it reaches the target temp. Also, it allowed the temp to drop exactly 10 degrees during the test before it cuts back in. Something I think this clearly demonstrates is the factory TC is mounted in the rear of the cabinet and either shouldn't be in the cabinet or it should have some type of insulator between it and the cabinet. If this was the case the temp swing would be less and the unit would be much more responsive. If you study the data you can clearly see that the air temp rises and falls more rapidly than the metal in the back of the cabinet. That's why the SG display temp appears to trail the ET73 temp regardless of rising or falling. The surrounding metal around the factory TC in the back of the cabinet is acting as a heat sink. The only difference in the data was during the warm up. The differential during warm up could be explained because the metal of the cabinet took longer to warm up than the air temp did.
A few things I learned from this.
- The DBS is really quite constant and fairly accurate.
- The DBS should really be monitoring the internal air temp as opposed to the temp of the metal in the back of the cabinet.
- When I install my TC for my PID I will make sure it is not mounted to the cabinet unless through an insulated thimble. This way it won't be influenced by the heat sink effect of the metal cabinet.
Although I did this test with the DBS more of less empty I feel the data was fairly consistent. If you had a load of meat in it I think it would be fairly similar with the exception of taking longer for temps to change. This longer time frame may effect the over run and under run temps slightly.
Mike
Thanks for running this test. Over the last 18 hours or so I've been wondering how accurate the temp readings were. I've had some butt in there since 6pm last night (cooking at 210 dbs setting) and neither piece is over yet. Was getting concerned that the cabinet temp reading was incorrectly high due to insufficient sampling. Instead simply sounds like I'm getting hungry (and impatient). Time to start getting ready for the game.
Cheers and thanks for posting your work, both on the PID and the temp sampling.
Mr. Walleye, That sounded like a 6 beer test and report. :D :D Your conclusion is the same as mine. :o A while ago I messed around with a wood thimble and Silicone to create the space between the walls and probe mounted across the thimble. I like your test criteria - it is repeatable.
The world changes somewhat with an 8 pound butt however - the mind twisting I think has the same causes but blurs over time. The butt initially is going to be cool and help keep the tower air temp cool. However, as it cooks and IT increases it 'sinks more toward the other direction and helps dampen the fluctuations. :o ::) ??? - Or so it seems. My kid tells me after 4 hours your at the cook point on an 8 pound butt and the temp swings become irrelevant for the balance of the cook. That seems to be true. --- thankfully...
I think the biggest thing I learned is that the DBS could be much more accurate if it simply had the TC located in such a fashion as not to be influenced by the metal cabinet.
Mike
Would probably not be a first choice to locate it in direct contact with the back or immediately above the heat element with the reflector focused in combination with the V pan on the back wall.
Hard to beat the idea of driving temperature based on cook area of the meat. You will have this solved in a short time though...
Your point and test is a good one on the consistency factor as well.
Take care,
wow interesting reading for sure....for whatever it is worth in my std bradly with the fan with no PID controller I'm 2 degrees up and down top to bottom empty box. It take me about one hour to balance the box on average so that I can just walk away from it. Do go out every 3 - 4 hours to look at it. I would do that even if I had a PID controller.
Quote from: Oldman on February 04, 2007, 06:16:37 PM
I would do that even if I had a PID controller.
I think it's mandatory isn't it Olds?
::) ::) ::)
Mike
Even though I have a PID, I tell my wife I have to check it all the time. No coincidence I pass the adult beverage refrigerator in the garage each trip.
Arcs_n_Sparks
Quote from: Oldman on February 04, 2007, 06:16:37 PM
wow interesting reading for sure....for whatever it is worth in my std bradly with the fan with no PID controller I'm 2 degrees up and down top to bottom empty box. It take me about one hour to balance the box on average so that I can just walk away from it. Do go out every 3 - 4 hours to look at it. I would do that even if I had a PID controller.
I have to say....I'm not sure about all the PID fuss. Like Olds, I spend an hour balancing the box and then walk away with a constant temp betwen 5 degrees either way. Did a 12 hour pork butt today and the temp stayed at 215 constant through the afternoon with the OBS.
Hi Mike.... Nice name by the way! ;D
I can't speak for anybody else but I personally can never leave good enough alone. You know what they say... good enough never is. ;D Seriously though I agree with you, you can produce some really good eats with both the OBS and the DBS without any modifications.
It's probably some deep rooted issue I have. ;D ;D ;D
Mike
For me the PID is a must convenience with my air temp variance and cold weather temp and wind it's a must for me on unattended smokes and overnights.
my 2 cents.
nodak
Where are my manners.....what I should of said is....Thanks Mr. Walleye (Mike) for the test you did (on a Sunday morning yet). The great thing about this forum is the sharing of information and expertise. The PID has always intrigued me but so far I have yet to find the need. Maybe it's the milder west coast climate that keeps the temps constant ;) Again... your contibutions are very much appreciated.
Cheers and Rauch those Beers....
yes that MIKE name is a great one indeed! ;)
Don't tell me we flopped a set!
A little poker humour
Mike
Not to be confused with necessity - all this PID temp - fan stuff. What else is there to do with a bradly. Dont have any bottom corners rusting out and hardware to reweld, dont even have broken hinges or steel that is warped and don't seal anymore with the bradley.
So what ya gonna do ??? Gotta play with something and if it gets better thats good and if it don't that's entertainment. ;) 8) :D
I just consider this the natural evolution of any hobby; the add-ons, hours, and tweaking can exceed the value of the original item in question. Of course, the value in all this is the satisfaction one gets from doing stuff...
However, I am ready with my MIG welder if required. 8)
Arcs_n_Sparks
now that we've flopped a set suppose we can catch a four of a kind or full house on the river? :D
sincerely
Mike
:D :D :D Sparkler and the MIG 8). No matter what - between now and the time I will go to my grave every spark makes me think about the Gizmo comment and the lightening bolts flying off your knuckles... -Storms aside not even static electricity will be the same again ;)
I wish throwing energy was as easy as Gizmo suggested; and believe me, I've been around lots of energy for a long time. I too will always be thinking of his observation, which was quite interesting. 8)
Time to move on to ball lightning. :D
Arcs_n_Sparks
I am waiting for Arcs to be Ambidextrous ..... Plasma cutter in one hand and the MIG in the other. Yeeeeoooooowwwwwww. :o
As much as I like the "purity" of using the wood fired smoker I bought 2 years ago, I just don't have the patience to be tending it every 25 minutes. This is especially relevant when it comes to briskets and butts (which is why I've only done 1 of each).
So... when I discovered the Bradley's I got VERY intrigued! I almost bought a digital one the other day but thought I'd do a little more research. I don't want to hijack this thread but it seemed appropriate to respond here as I'm concerned (well, curious really) about the reliabilty of the digital vs the original. Are they really worth the difference in price? (actually only $30.00 difference here in Vernon, BC).
btw... these things don't create a smoke ring? WTH! Isn't that indicative of flavour permeating the meat?
Cheers
Silver
Go original. ;)
What Icerat said Plus build a PID
Smoke ring (pink ring) is not created by smoke penetration, and is not an indication of flavor. It is a chemical reaction that does indicate that the meat was cooked "low and slow".
You can only get a "smoke ring" by cooking over organic fuel such as wood, charcoal and/or gas at a low temperature. Burning of these types of fuel produces trace amounts of nitrogen dioxide. When it comes in contact with the meat surface it dissolves and eventually converts to nitric oxide, which reacts to the pigment in the meat to form a "pink ring". This can penetrate to a depth of about 1/3"-3/8" (8-10 mm). Although you are producing smoke in the BS, the bisquettes are not burning hot enough to produce traces on nitrogen dioxide, or in the amount that would be needed to create a "smoke ring."
Habanero Smoker if I understand you, Is it possible the Propane version could create the smoke ring effect?
Go original - go original - go original.
Quote from: nodak on February 19, 2007, 01:11:39 PM
What Icerat said Plus build a PID
PID? Okay, now I know I must be a noob. What is a PID? How does one 'build one'? How necessary is it to build/have one? And to get this thread back on track... Walleye suggests that the temp swing with the digital unit is "quite constant and fairly accurate". Hmmm... if Walleye would like me to start a separate thread for my questions I gladly will.
Cheers,
Silver
Smoke ring puts polyps in your pooper ::)
Origional saves you some money that can be spent later to fund to add on toy of your choice. The temp set on the OBS folks here say is not a big deal to learn to tweak.
The digital you dont tweak. The DBS temp variation is nothing compared to the chunk smoker you were using.
Either unit will meet the needs you expressed.
A PID is a temperature control scheme that provides a very accurate control over the temperature on either the DBS or the OBS. Building a PID is not necessary at all. There are many postings here about how to build and troubleshoot one. They are fun additions to the smoker.
Walleye is right on about the temp swings on the DBS being constant and fairly accurate. The trick with any of the smokers is understanding the varibles that are at work. It is something that is learned as you smoke what you like to eat in the amounts you smoke it.
The one thing you will love about the Bradley is the ease of use with either unit. You will smoke more often and less amount at a time. At noon yester I did one roasting chicken. No way do you start up a chunk wood smoker and tend it for a single chicken. That is huge easy. I use DBS, with a do over I would keep DBS ... I can add the toys and keep a couple of features.
Hi Silver and welcome
No problem fro me on the thread... ask away. I couldn't agree more with West Coast. I don't think you can go wrong with either the DBS or OBS.
Mike
Silver,
IMHO its not about the purity anymore, it's about the smiles, eyes of content, and ease of use. The palate is more telling then methodology. As much as the temp swing bugs me on the digital, if it were a $30 dollar difference, I would still get the digital. The repeatability of setting the number instead of a slider should be a bit more convenient. The only reservation I would have (again with only a 30 dollar bill difference) is the heat capability between the two units. From what I have seen here, it appears the Original has (or at least had) a hotter oven heater. If that is the case and you are in colder temperatures, there might be an advantage with a hotter heating element to keep the temp up.
I think they were / are the same wattage. Difference was metalized or glass ??? Need a hero with history here. The 4R does have somewhat less volume to heat than a 6 rack but I like the spreads you lay out with your 6R DBS Gizmo. Whoping Gobs of Food :o
Quote from: nodak on February 19, 2007, 03:34:34 PM
Habanero Smoker if I understand you, Is it possible the Propane version could create the smoke ring effect?
Though I believe the article I read was referring to natural gas; propane is an organic fuel. It should produce a pink ring.
WOWZA... uber-helpful info from everyone. Special props to West Coast Kansan. Thx. :)
BTW... the DBS I'm looking at is the 4-rack one so it should get up to the same temps as the OBS (I would think). For the $30.00 diff. I think I'll go with the digital (retail $399.00 Canadian @ Surplus Herby's , which seems pretty good compared to what I've been seeing elsewhere).
Glad I found this place... helpful people talking about their pits. I do believe I've got me a new home...
*takes folding chair out of bag and sets it down next to the cooler.... cracks a cold one*
;D
Quote from: Silverlock on February 20, 2007, 09:08:32 AM
*takes folding chair out of bag and sets it down next to the cooler.... cracks a cold one*
;D
Wow!!! Silverlock already skipped to step 4. You're a fast learner and my kinda guy :D Welcome to the world of "BS" as Ann calls it ;D ;) :)
Quote from: Gizmo on February 19, 2007, 08:56:55 PM
Silver,
IMHO its not about the purity anymore
I know but... :( ... c'mon...
(http://i112.photobucket.com/albums/n191/Remillard_ca/Pics016Medium.jpg)
There is something about the esthetic and purity. It's almost a piece of lawn art too! *Sigh* Gonna miss it.
Thats why they invented Pictures> Cherish the memories Silver. I guess you could hang onto it like an antique and pay it attention when the heart grows fonder. ;)
I still have my Meco charcoal water smoker, and use it from time to time. It produces a different flavor. Some times I miss the flavor of charcoal, and using peach wood to smoke with.
Peach wood! I have never tried that - hey Chez think you could talk Bradley in producing some? ::) ;D
With the Weber "Darth R2D2" style water smoker, I used to smoke with almond wood quite a bit with good results. Never tried peach though.
I thought the pecan bisquettes would be similar to almond, but not so. Still turns out a good meal though.
Hmmmm. Almond sounds good also. ::)
Quote from: Wildcat on February 23, 2007, 04:11:43 AM
Peach wood! I have never tried that - hey Chez think you could talk Bradley in producing some? ::) ;D
I did send Bradley an e-mail suggesting that they make bisquettes out of peach wood, but they politely responded that they have no plans to do so. :)
Quote from: Habanero Smoker on February 23, 2007, 01:56:12 PM
I did send Bradley an e-mail suggesting that they make bisquettes out of peach wood, but they politely responded that they have no plans to do so. :)
??? :P :( :'(
Quote from: Silverlock on February 19, 2007, 04:15:37 PM
Quote from: nodak on February 19, 2007, 01:11:39 PM
What Icerat said Plus build a PID
PID? Okay, now I know I must be a noob. What is a PID? How does one 'build one'?
Cheers,
Silver
Well, depending upon a number of factors, the PID is either a:
Pig
Indicating
Device, or a
Porter
Indicating
Device, or a
Proportional,
Integral,
Derivative closed-loop controller
Depends on whether you are shopping, drinking, or controlling..... 8)
Arcs_n_Sparks