Author Topic: Temperature Test Pt. 1  (Read 203 times)

Offline Habanero Smoker

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Temperature Test Pt. 1
« on: July 22, 2020, 01:38:17 PM »
Another long post. I decided to break it down into two parts. I’ll post part two, which is much longer, tomorrow. That part will include my conclusion. Part 2 will consist of tests of two rack positions, using four probes.

I’ve done two cooks with the BS1019 and I felt that both cooks went faster than I had expected, so I decided to test the smoker’s accuracy with a third party probe. For these tests I used my ThermoWorks Signal. Because of the door design, and how tight the door closes I didn’t want to ruin the door seal or possibly the probe wires. Therefore I removed the damper, and condensation bowl. Then I was able to run the probes through the vent. Each test was performed with an empty cabinet at a cabinet temperature of 251°F, and while the smoker was in the shade. Why 251°F instead of 250°F? While setting the temperature when using Fahrenheit, the adjustment is in 2°F increments.

It appears that the Bradley auto tunes itself each time you turn it on. When it is first turned on it heats up rapidly until it gets within about 10 degrees of the set temperature, then slowly brings it up to your set temperature. This auto tune can take up to 5 – 8 minutes.

Test #1 at sensor level:
Ambient temperature 82°F, approximately 2mph breeze, humidity 62%, damper removed; set temperature 251°F. During preheat I place one probe within two inches of the Bradley sensor, and a second in the middle of the rack. During the preheating the probe near the sensor read as high as 39°F higher then what the Bradley was displaying. This is probably due to how they programmed the PID. This probe was directly above one of the heating elements. I didn’t place the second probe in until the smoker reached the target temperature. After about 30 minutes of monitoring the temperature, the average reading of the rear probe maintained about a 24°F - 27°F higher than the Bradley display, and the center averaged 16°F - 18°F higher than the display.



     I
         don't
                   inhale.
  ::)

Offline manxman

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Re: Temperature Test Pt. 1
« Reply #1 on: July 23, 2020, 01:00:23 AM »
Had to convert temps to Celsius first to better understand your findings Habs  :) but in any language the around 10% discrepancy seems significant when trying to cook low and slow?

I suppose the first question is if we make the reasonable assumption your third party probes are the “gold standard” are the Bradley sensors accurately calibrated? Given you said your first two food smokes had gone quicker than expected perhaps the Bradley cabinet sensors are giving false low readings?

Forgive my ignorance of the P10 but does it have a fan to aid heat circulation? If the probes are all reading accurately then it would suggest variable heat circulation within the cabinet which goes back to some people adding a fan to the older models?

Or am I being too picky about the discrepancies?  ::)
Manxman

Offline Habanero Smoker

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Re: Temperature Test Pt. 1
« Reply #2 on: July 23, 2020, 02:24:51 AM »
Wait until you see the results of part 2.

One of these days the U.S. will convert to the metric system, but I've been hearing that since the early 60's. :) My ThemroWorks products have been fairly accurate, but it wouldn't hurt to check their accuracy. I was disappointed in the discrepancy of the range, but for barbeque it's not that bad. I always barbecue at the high end of low and slow, except for my butts. Once the temperature steadies, although high, it keeps the temperatures within 1 to 2 degrees. So I just have to learn how this cooks. Also I don't know if I will get totally different results once food is placed in it. I may try a test this weekend with food. A local supermarket had leg of lamb for $5/lb.

There is not a fan, and I'm kind of surprised that the back of the smoker is so much hotter. Though it doesn't have a fan, it has two equally spaced 400w heating elements that run parallel (side to side) to at the bottom of the cabinet. These elements are above the drip tray, and each is tent covered with a small piece of stainless steel. So there is nothing obstructing the heat from the element. This alone I thought would distribute the heat evenly. I'm sure there will be future firmware updates to improve heating.



     I
         don't
                   inhale.
  ::)