Now I am confused, not that this would be the first time. I have completely cleaned the inside of my Behmor. I then mounted a thermocouple just behind the clip the bean drum rides in on the left side of the roaster. It never measured higher than 270 degrees F. I was roasting 13 oz of Guatemalan. I used a 1:45 preheat without the beans. Roaster measured up to 178 before I cut it off. The beans roasted as well as I have been able to achieve with the Behmor. My laser temp probe registered 380 when I cracked the door and pointed the laser at the beans. Can someone explain the difference in the two temps? Is this normal? Is my temp probe faulty?how can I use this data? Thanks, Hank Homeroast mailing list Homeroasthttp://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.comHomeroast community pictures -upload yours!) :http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20 |
My guess is that you were picking up the heat from the elements. Ken |
Coming out of lurk mode: My result doing this are similar...The thermocouple just behind and above the clip on the left side of the roaster measures not much higher than 300 degrees F. I usually roast 12 oz of beans. My laser temp probe at end of roast is usually registering around 400 degrees at the end of a city plus roast. I assume the air temp never gets to high because the beans are being roasted primarily by radiant heat and the bean temp measurement is measuring the surface temp and not the bean mass. I just use the info as a gauge or comparison to previous roasts. I have tried to use the air temp to gauge how long I open the door to drop the temp when I do that. Truthfully, it's not so good an indicator as it doesn't seem to change much. When I open the door and see it drop I know it's probably time to shut the door again. Though the reading are pretty inconsistent. So I'm pretty curious about this as well? Stan Las Vegas, NV Now I am confused, not that this would be the first time. I have completely cleaned the inside of my Behmor. I then mounted a thermocouple just behind the clip the bean drum rides in on the left side of the roaster. It never measured higher than 270 degrees F. I was roasting 13 oz of Guatemalan. I used a 1:45 preheat without the beans. Roaster measured up to 178 before I cut it off. The beans roasted as well as I have been able to achieve with the Behmor. My laser temp probe registered 380 when I cracked the door and pointed the laser at the beans. Can someone explain the difference in the two temps? Is this normal? Is my temp probe faulty?how can I use this data? Thanks, Hank Homeroast mailing list Homeroasthttp://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20Homeroast mailing list">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.comHomeroast community pictures -upload yours!) : http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20Homeroast mailing list Homeroasthttp://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.comHomeroast community pictures -upload yours!) :http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20 |
Check your probe in your kitchen oven for comparison. My probe is just below the bottom element and I get to 200 F in one minute pre-heat and am usually at 430 - 450 at first crack. -Chris Pecked out on my mobile phone. On Nov 11, 2010 9:33 AM, "Hank Perkins" wrote: <Snip> completely cleaned the inside of my Behmor. I then mounted a thermocouple just behind the clip the bean drum rides in on the left side of the roaster. It never measured higher than 270 degrees F. I was roasting 13 oz of Guatemalan. I used a 1:45 preheat without the beans. Roaster measured up to 178 before I cut it off. The beans roasted as well as I have been able to achieve with the Behmor. My laser temp probe registered 380 when I cracked the door and pointed the laser at the beans. Can someone explain the difference in the two temps? <Snip>http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20Homeroast mailing list">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.com<Snip>http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20Homeroast mailing list Homeroasthttp://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.comHomeroast community pictures -upload yours!) :http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20 |
Ok. I will test it. Thanks, Hank Perkins Perkins Technical Services Cell 256-426-0543 Work 256-539-6787 Sent from my iPhone On Nov 11, 2010, at 2:02 PM, Yakster wrote: <Snip> Homeroast mailing list Homeroasthttp://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.comHomeroast community pictures -upload yours!) :http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20 |
I checked the probe, it was ok. I reinstalled per Chris' suggestion. The teems got up into the upper 300's. Interesting thing, on P1 the temp fell 100 degrees at the 10 minute mark. It stayed down until the 15:30 mark. I thought P1 was full power for the whole roast. On Nov 11, 2010, at 12:25 PM, "Ken Schillinger" wrote: <Snip> Homeroast mailing list Homeroasthttp://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.comHomeroast community pictures -upload yours!) :http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20 |
At 09:30 AM 11/11/2010, you wrote: <Snip> Yes <Snip> Since you can't get the probe in the bean mass all you can get is the environmental temperature at some point in the roaster. I have 2 probes in my Behmor and one reads 100 degrees hotter than the other. The hot one is taped to the bottom and ends up in the middle of the rear wall near the elements, the cold one is hooked over the chaff tray on the left side. It's unclear that either gives useful information but you can see things like the starting temperature and the rate of rise for the first few minutes which might be useful indicators. You can also see when the afterburner turns on. Ira Homeroast mailing list Homeroasthttp://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.comHomeroast community pictures -upload yours!) :http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20 |
At 03:33 PM 11/11/2010, you wrote: <Snip> That's when the afterburner and fan turn on. Ira Homeroast mailing list Homeroasthttp://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.comHomeroast community pictures -upload yours!) :http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20 |
Hank, a thermocouple develops a "Seebeck" potential at the junction of the two wires. The potential depends on the metallurgy or exact composition of the two wires and the temperature at the junction. The junction temperature is exactly what you are reading on your meter. Except Except Except- if the wires pass through a sharp hole in a metallic piece, the insulation could be abraded, and the wires short to each other or the metal plate. The short is your new measuring junction, probably not too hot. Assume a nice clean electrical installation with no spurious junctions or corroded connections. (A corroded wire junction is totally different from a clean junction- a completely different thermocouple junction than the meter's calibration, so the readings are false.) A good thermocouple from an electrical standpoint is part of the story. A type J thermocouple (red, white wire insulation; black connector bodies) uses iron and constantan wires for the couple. It develops a higher potential for the same temperatures- it's useless with a K-calibrated meter. Coat hangers are iron wires- strip off the paint and you instantly have rusty iron wire. Bad for coat hangers and thermocouples. Metal-sheathed thermocouples are quite rugged mechanically, but you have to account for heat flow to- and away from- the junction. The measurand supplies heat to the junction; everything else takes heat away including the sheath and the thermocouple wires themselves. Anything that moves the thermocouple, even slightly, during the roast or from roast-to-roast with a poor installation will change its sensitivity and give different numbers. Apparent advantage: IR Cheers, Mabuhay -RayO, aka Opa! Absent the Grinder, Roasting is a caseless hope. Homeroast mailing list Homeroasthttp://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20">http://lists.sweetmariascoffee.com/mailman/listinfo/homeroast_lists.sweetmariascoffee.comHomeroast community pictures -upload yours!) :http://www.sweetmariascoffee.com/gallery/main.php?g2_itemIdx20 |