I believe I just finished my 6th or 7th roast On my new Bullet! YAY! I’d like to understand what is going on with my preheat, and maybe how I can achieve what I’m trying to do (or understand why i’m doing it wrong). I’m a recent Hottop convert so I’m familiar with Artisan, and I’m also a little familiar with quirks getting Environment temperature and Bean temperature where you like them. I’m still struggling to figure out the in’s and out’s of RT3, but that will take time. I don’t understand why my preheat acts the way it does. “Charge Settings” is set to 427F, and it says it should be based on Bean probe, yet it clearly is IBTS, and doesn’t tell me to charge till the Bean Probe reaches 288F? Also, I did set the Roaster to start at P8 and 390F… Both were ignored?? HA! also the RT3 crashed on my last attempt, gave me a white screen of death lol!! I’d really like to understand why the Charge Settings doesn’t follow what I set, nor follow what I set on the Bullet through the pushbuttons either? Thanks
Here’s what I believe to be the steps to get thru Preheat as part of a Recipe…
The Preheat mode allows the user to select a target temp but not any parameters that affect how it gets there. Preheat uses IBTS (Drum Temp) to determine when you have reached the target temp. The Bean Temp probe is measured to determine that it’s stable after the Drum Temp hits the Preheat target but it isn’t used to determine the Preheat target. How it does that is internal to the f/w. The operator has no control of any power, fan or drum settings. The roaster f/w uses P7, P3, P1 and P0 to get the drum to the Preheat target and the only thing you can do is watch. Once the drum gets to the target (it won’t be exact) the power cycles thru P3, P1 & P0 while f/w monitors Bean Temp till it decides it meets it’s internal stability criteria (if it’s still rising rapidly it lets that continue till it stabilizes all the while managing Drum Temp at the selected Preheat. Charge Settings are what the Recipe sets power, fan and drum to when you charge the drum after Preheat is complete.
In the Recipe you get to select that target temp but internal to the f/w are preset intervals based upon 5C° steps above (I think!) 185°C. The f/w converts the Control Panel display to show the F° equivalent if that’s what you set the Bullet to use- which turns out to be steps of 9F° starting (again, I think) at 365°F. Choosing 367°F as the target is still going to give you a target based on the starting point (either 365°F or 374°F). IBTS swings above and below the set point but not far off.
In terms of operation, to get the Recipe to set the target Preheat you have to first start the Recipe then you can go to the Roast page and launch Preheat. If you launch Preheat then go to the Recipe page and launch a Recipe, the roaster will continue to Preheat at the setting preset into the f/w during setup. If the Recipe Preheat temp is the same as what you set into the f/w during setup it makes no difference, but if the Recipe and the preset Preheat value in the f/w are different, the f/w always wins unless you first launch the Recipe then go to Roast and start the Preheat.
As an example, I do most of my roasts at a Preheat of 392°F and I also have the f/w defaults set to 392°F. To launch the Preheat I first start the Recipe then go to the Roast page and start the roast which launches Preheat mode. I have another Recipe that uses 410°F for Preheat and if I want to do that as part of the same session I Cancel the original Recipe button in lower right cornet) then launch that other Recipe with the higher Preheat before going to the Roast page and starting the cycle again. There are additional options how you get to this same point that are related to doing BACk-to-back roasts.
Um, I don’t think so, but they might have different operations depending on f/w builds. I modified from my above image to Preheat Temp 500F Then P0 D9 F0 which would indicate that power would drop to zero once the CHG is detected (or pressing PRS). This didn’t happen, it went right to the second line item, which was set to P8 D9 F0 (again, not pictured above) I believe the top Charge Settings only sets PH Temperature-nothing else is used from that line item. The system monitors BT ROR once the IBTS reaches the Preheat Temperature. It seemed like the BT ROR was less than 5 for several seconds to initiate the CHG Ready state.
Again, more lockups on the GUI, but Im glad that the system remembers the last state and just restarts easily.
As for Charge temperature, I was having a conversation on Facebook (yeah, yeah, I know), and it was suggest to charge significantly higher as in what the manual shows on page 34, way over 500, into 527-590 range. Honestly, that 500+F charge temp from the IBTS is WAY too hot, but the BT is only reading 347F when IBTS is reading 500F. Now it seems like every source recommends between 360F-390F for charge temps @ 1kg. My next experiment is to fake charge when it reaches 500, then wait a minute, the drum drops down to 450F, but the BT doesn’t fall so it stays at 347F when I drop a minute into the roast.
Thanks for the info! It was very helpful to understand the operation a little clearer.
I think that’s normal.
The BT probe in an empty roaster is air temperature, the IBTS is the drum temperature. The air will not be anywhere near as hot as the metal because cool air from the room replaces hot air in the drum.
So it’s normal to have a very large gap before charge. When you add room-temperature beans, the BT drops quickly, and starts climbing as the beans heat up to almost nearly the drum temperature.