BDS WEIRD heating with frogmats?

[fishrman]

This morning smoked four 3 pound boneless turkey breasts in my BDS with the BBQ Guru and newly installed recirculation fan.  Everything worked great, temp was set at 225F and were achieved with no issue, without a hitch.  Took out the turkey and put in 8 racks of jerky with frogmats on all the racks.  Temp probe was clipped to the bottom of the second lowest rack.  At the drying temp of 140F all was well.  Turned it up to 150F for the two hours of smoke and it hovered around 148.  Then upped the temp setting to 175 but that's when the weirdness started. 

BSD meat temp display rose to 218F but the BBQ Guru display would not cross 150F.  After an hour I opened up the BDS and the jerky meat was still pale and very moist, and the temp sure seemed low.  The racks were double stacked (second rack upside down on top of the first rack in standard position) and I unfortunately did not check the meat on lowest rack that was hidden by the double decker rack.  Checked to make sure there were no new sources of current drain on the power supply.  Turned up the temp setting to 180F but could not get the temp to budge on the Guru display.  Was watching the game so checked only infrequently and was frustrated to see the meat still pale and moist after 2 hours at the 175 setting.  Turned on the oven to 175 and pulled the racks from the BDS to transfer to the oven. 

I then discovered that the bottom most rack and the back of the second rack were at that point transformed into charcoal.  All I can figure is that somehow the finer mesh of the frogmat did not allow the heat to circulate evenly and the radiated heat from the heating element caused the charring of the lowest rack of meat.  But I still don't get why eventually the whole smoker would not have heated up.  As a check of the smoker, after I pulled the meat I left it on with no change to any settings and clipped the Guru probe to the guide rail for the second lowest rack.  Sure enough, within 5 minutes the temp in the smoker had risen to the set point of 175.

Looking to your experience for some answers here as I have to admit to being totally lost on this one.

[KyNola]

Frogmats had nothing to do with this.  First, you were comparing BDS digital temp readings to the BBQ Guru.  The BDS temp readings are notoriously off.  Second, you had 8 racks of wet meat in the tower.  That is a large load.  Hopefully your vent was 100% wide open.  You didn't mention rotating your racks, front to back and top to bottom.  That would explain the "burned" jerky.  Lastly, take the load of 8 racks of wet jerky out of the tower and the temp will absolutely shoot up.

You didn't mention how long you had your jerky in the Bradley for the different temp settings you mentioned.

[fishrman]

Kynola, I've done 3 other 8-rack loads in the last month without the frog mats and had no issue, thus my question about the mats.  I'm aware of the expected difference between the Guru and the BDS as I found this with my maverick early on, I was just surprised here by the ~70F difference as I never experienced anything that dramatic before.  I really only mentioned it as it seems that to achieve that high of a reading the heating element must have been cranking out some serious wattage during this period. 

Working from memory, here's how the timing worked at the various temp settings.  Vent was open 100% at all settings, no water in the bowl at any time.

1 hour at 140F (achieved Guru reading of 140F)
2 hours at 150F (achieved Guru reading of 148F)
2 hours at 175 (Guru reading never hit 150F)
2 hours at 180 (Guru reading never hit 150F)

You are correct that I did not rotate the racks.  From what I could see when I checked the meat it was still pale and moist on the visible pieces so did not think it was time to do so yet (bad assumption). 

On the previous jerky smokes had no problem hitting the 175F, no problem hitting the 225F earlier in the day, and after 5 hours nominally at 150F with a fully open vent I would have thought there wouldn't be too much moisture left in the meat to prevent the temp rise. 

[Habanero Smoker]

As KyNola pointed out, it has nothing to do with the frogmats.

If I understand correctly, you placed the probe of the Guru in between the second and bottom rack position. If that is where you placed it, you will get a false cabinet reading, and the bottom rack is going to be exposed to a much higher heat. In this case, a 70°F difference. The best location  of the probe would be on the bottom rack; towards the front, and as far away from the meat as possible. And with jerky, it is best to rotate.

Also with the DigiQ, if it is not already disabled; disable the "Open Door" feature. See if that improve the temperature control. If you see no improvement or the DigiQ doesn't seem to hold the temperature well after it has been disabled, enable it again.

[Wildcat]

Was there enough of a gap between pieces of meat to allow heat flow? With frog mats I would think too much blockage of air flow could be the culprit if one were trying to maximize the load. Just a thought.

[Mr Walleye]

I'm on the other side of the fence on this one.  :D

Frog mats are a finer grate and therefore restrict more air. For windows or porches they make wind proof screen which is very fine. Back to the frog mats, I don't think in a normal situation that the frog mats would reduce the air flow enough. However, when doing jerky you are putting thin layers of meat across the entire tray. Add to that, you have 8 trays, add to that, you have frog mats on all 8 trays. It has to restrict the air flow somewhat. In addition, the meat juices have a tendency to block the holes in the frog mats closest to the meat which further reduces the air circulation. I think when you are pushing the envelope with regards to load size, small changes with regards to air flow make a fair amount of difference.

For myself, I don't use frog mats for jerky. I do for things like butts, brisket, salmon, etc. 8 trays is a big load and regardless, will require a lot of rotating for sure.

Mike

[mikecorn.1]

I just had same issue with temp using a fan. I'm experimenting with it
Today with/without frog mats, location of probes, and fan on and off. 


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[OldHickory]

I am with Mr Walleye on this one.  I don't use frogmats, IMHO they act as a baffel to heat and air circulation.

[fishrman]

Habs, thanks for the advice on the probe placement.  I've used it on the second rack before, but do the the logic in what you suggest.  I was worried about the radiated heat from the element causing a false high reading if I put it on the lowest rack, but by having it up front the drip pan should diffuse that sufficiently!  I disabled the open door feature when I first got the unit after seeing what it's purpose was.  As I say, it has worked perfectly on all previous smokes.

Wildcat, I had the same spacing I had when I did the same jerky load on the bare racks and did not seem to have an airflow issue.  But I can see that the mats do create a fair amount of additional blockage which could point to loading the racks more lightly when using the mats.

Mr Walleye, first, I've never fished for walleye, but it is on my to do list for sure!  I've seen lots of TV about it and it looks like a blast.  Before I bought the frog mats I saw a number of posts by folks who swore by them for Jerky, indicating it made clean up a snap and eliminating the sticking jerky issue.  I'd be interested in the results of those who read this and use the mats when loading the smoker with jerky.

Mikecorn, I'd be interested in seeing what your experiments result in.  Please make sure you share your results!

OldHickory, I'm certainly baffled by Frogmats at this point ;).

[Wildcat]

I use frog mats but I generally just smoke butts, brisket, ribs, and chicken. I will eventually do nuts and jerky. I have not had a problem with the mats, but I generally do light to medium loads as there normally are only two of us and we go out to eat a lot.

[Habanero Smoker]

I feel you will get better results with that placement, and along with rotating the racks hopefully you will see improvement. I don't do that much jerky, but Mike is familiar with air flow so he might be on to something. His theory, plus the evaporation of moisture from the meat that significantly cools the air surrounding the area, may combine to exasperate the problem. So when you place the probe in between racks, and with such a large load you will get that lower reading.

With the Bradley I've only had problems with radiant heat  when the meat is very near the back of the smoker. And the problem worsens the closer you get to the element.

[Mr Walleye]

To add some more to this and Habs comment regarding the moisture given off the meat and how much it can influence the surrounding temps. With 8 racks, using the inverted rack method, you had the temp probe on the bottom of 2nd rack. I'm assuming this was below the standard 2nd rack position, meaning it really had 2 racks below it when you count the inverted rack. Another thing that could affect the lack of circulation through out the cabinet including around your temp probe is how you lay the jerky on the racks. As an example some people lay the jerky all the same direction on one rack, then change the direction on the next rack above it and so on. Not that this is good or bad, it just may further influence the temps above it from the cooling effects of the moisture being given off.

Something else to keep in mind is the air flow coming off the circulation fan is on about a 45 degree angle towards the door of the smoker but on an upward angle as it comes off the blades of the fan. Two things come to mind here, one, when loading the lowest tray if you lay the jerky strips front to back to allow the most air flow at that angle through the rack from the circulation fan. The 2nd thing that comes to mind is because the air coming off the fan is at the 45 degree angle, the frog mats finer mesh and associated air flow restriction is further magnified at that angle.

I agree with Habs regarding the probe placement. I always want to know and control what my meat (lowest rack) is being exposed to. Certainly having it placed between a regular rack on the 2nd position and an inverted rack above the lowest rack, there would be limited room and clearly could have been influenced by the meat temperature inself.

It would have been interesting to have had a temp probe below the lowest rack just to actually see what that level was being exposed to because I suspect the temps where quit high.

I think it's fair to say that what happened was the temp probe for the Guru didn't have adequate air circulation around it and between that and the moisture off the jerky contributed to the lower temps that it was seeing. The entire time the Guru would have been calling for more heat and been running the heating element flat out causing the jerky in the lower rack to turn to charcoal.

I know, I know... I'm a little anal about details!  ::)  ;D

Mike

[viper125]

I've also had problems with Bradly with a full load. Like they say wet meat and just to much too heat. Mats just probably made it worse. The only fix I found was moving racks as you cook to not burn meat. Also its not done till its done. Some times easier to do in multiple batches.

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[fishrman]

Viper, I guess there is a learning curve with the mats and that jerky smoke was just my first day at school. I've done that same load without the mats multiple times with great results, so will just have to keep working on it to find the right balance. One thing I did find was that cleanup was not that much easier as the meat juices/fats of course flowed right through the mats onto the wire trays requiring the same elbow grease to get clean.

[Habanero Smoker]

Even with a smaller load, if the probe is too close to the food source or in between trays, moisture evaporating form food can lower the surrounding air by as much as 40°F.