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ET and BT Thermocouple Placement?
brennn
I am currently modifying a Poppery I.

For those that have modified a poppery, or similar popper, where have you placed your ET and BT Thermocouples?
 
Airhan
The ET should be through a hole in the interior aluminum/metal housing right inbetween the fins at the bottom of the roast chamber. BT location is a crapshoot.
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
Airhan
This forum on homebarista shows a good bt location.

http://www.home-b...23853.html
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
brennn
Airhan, thank you for your response. To clarify, the BT should be in the roasting chamber itself, to measure the bean temperature, and the ET should be representative of the heating element temperature?
 
Airhan
Brennn, you are correct about the BT, the ET is the temperature of air entering the roast chamber, not the temp of the heating element.
BT= bean temp.
ET=environment temp.
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
brennn
Thanks for the clarification!
 
Airhan
No problem! You should post some pictures of your work in progress, show off a little!
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
brennn
From a roast-logging perspective, which thermocouple is more important? BT or ET?
 
ginny
ET and BT Thermocouples:

do you know the difference between the two? which is more important to you in your roasting?


ginny
 
brennn
Thanks for the response, ginny. I do understand the difference between them. I ask because I may only use one thermocouple and I want to know whether it should be placed in the circulating chamber or at the spot where the heat flows into the chamber.
 
brennn
If I am unable to get my thermocouple close enough to be considered "ET", could I just place both in the chamber, thus giving me two BT readings?
 
Airhan
If I were to only have one thermocouple, I'd want it in the roast chamber to know the bean temp. You probably don't need the redundancy of two bean probes.
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
brennn
Sounds good, Airhan. I'm just hesitant to open up my popper to secure an ET thermocouple...
 
Airhan
There are no rules about what you have to do brennn, lots of people get by with not instrumentation at all, temps are just another way to know what is going on with your beans.

Just do as much as you want/are comfortable with. I've only taken my poppery apart twice, and I seriously hope I never have to again. You can always add more later If you just do a BT probe now, most folks on here that build their own roasters are always tweaking and improving them.
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
brennn
I currently have a Thermocouple from SparkFun - (K-Type Glass Braided: https://www.sparkfun.com/products/251)

If I place the bare thermocouple into the roasting chamber (as a BT thermocouple), would the beans damage the thermocouple?
 
Airhan
I would not worry at all about damage it from beans hitting it.
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
brennn

Quote

Airhan wrote:

I would not worry at all about damage it from beans hitting it.


That's great to know! Can you say this from experience?
 
Airhan
Experience: farm6.staticflickr.com/5490/12110002095_352723409c.jpg

My thermocouple is just twisted together, the one you got from sparkfun should have a bead of solder holding the ends together, neither of these is superior. Mine is just stuck into my RC through a hole in the side and held in place with a bold&washer(not seen in this picture).
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
icantroast
Where is a good place to get fahrenheit thermocouples (and display) for cheap?
 
Airhan
If you want cheap, look on ebay: http://www.ebay.c...5d42376f14

http://www.ebay.c...20d586a96c
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
brennn
I successfully did my first test "roast" today! It just consisted of turning my fan and heater to different levels, but it is exciting nonetheless!!!
i.imgur.com/tGuOyvv.jpg
 
Airhan
Nice brennn! When are you going to experiment with some beans?
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
brennn
I'm going to start experimenting with beans as soon as I figure out a way to close my project enclosure without shorting any wires! I'll be sure to keep you all posted.
 
Airhan
Don't forget pictures!
Aaron
"Grind it like it did you some great injustice!"D.L.Clark
 
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