After my last roast session I did the deep clean. But after I was all done, realized I had forgot to clean the IBTS. Didn’t want to take it apart again so figured it was fine. Start my next roast session and after warm up I get ERC 0001, but get it to go away. Didn’t want to go through cool down and warm up again so figured I could get through roasting and clean it afterwards. 3 erratic roasts later I finally had to concede, cool down, take apart, clean the IBTS and start over.
Before the cleaning things were all over the place. Roasts were going very quickly. Temp readings weren’t even close to what was going on (YW, FC, etc…). Bean and drum temp lines were crossing over each other.
After cleaning, everything was perfect. Playbacks were right on.
Dirty sensor was causing false readings on the lower temp side. So roaster was actually much hotter than it was showing.
I think some context would be helpful for many of us as it relates to the cleaning rituals and upkeep to keep things moving smoothly for each of us on this roaster… That said, How many roasts had you done prior to this point?
You can clean the lens gently with an earbud dipped sparingly in isopropyl alcohol. You will then need to use a dry bud to clear away the haze that the alcohol leaves behind. Make sure you do not push the sensor back. Doing that can leave a small gap at the back through which fine dust/chaff can settle in the IBTS fan and cause a build-up that can lead to errors.
I found the interval for cleaning the IBTS is more related to temperature during a roast than counting roasts/roast sessions. Counting presumes all roasts deposit the same amount of roasting snot on the IR sensor lens. I’ve convinced myself roast-count is variable depending on how dark you roast and how much chaff/dust your greens are throwing off.
What I’ve done for perhaps 2 years is to note the maximum difference between IBTS & BT during each roast. For the batch size I use (550 gm) and my preheat temp (392°F) that happens somewhere around IBTS = 250°F and the value I look for is 40F° or more on a clean sensor lens.
The specific IBTS temp isn’t what’s important… it’s the difference between the 2 readings. That difference will decrease as the roasts accumulate. In my case when it gets down to about 37F° it’s time for me to clean the IBTS again. I do other cleaning (front plate, exhaust fan, transfer tube, bean chute, chaff filter) in between IBTS cleaning- maybe every 3 roast sessions? I haven’t logged it so I’m working from memory.
An important thing to consider is that Preheat uses only IBTS to set Preheat temp. If the sensor is dirty, IR is being partially blocked from reaching the sensor. That causes drum temp to reach a higher than the programmed value during Preheat. A clean sensor lens (it’s just a flat clear covering- there’s no diffraction involved) allows more of the IR to reach the sensor. That means a higher IBTS reading for the same drum temp than a dirty sensor would measure.
In an earlier post I mentioned that the oil/smoke/dust which accumulates on the lens isn’t soluble with alcohol, but the alcohol does soften the roasting snot. So it takes a lot of repetitions to get it clean. Unfortunately whatever the composition of that contaminant it isn’t visible on the white cotton of the swab. So there are no visual cues to tell you the surface is clean.
Also, the first time the IBTS is cleaned seems to take more effort (which may simply be learning what to expect).
There are variables in using temp difference to judge when to clean the IBTS-
The difference between IBTS and BT decreases as batch size increases. That means the difference used to judge when it’s time to clean will be a smaller number. You can scan thru your roast history to get a feel for what may work for you.
Conversely a smaller batch size will have a larger difference between IBTS & BT. So again you will need to scan thru your roast history to see how the difference in temp has diminished with the number of roasts.
For regular cleaning, why don’t Aillio consider making the IBTS plug and play? So that the IBTS sensor can be unscrewed from the face plate for cleaning, without the need to open the entire face plate?
I think it’s because the IBTS fan is on the outside of the face plate, and housed where the control board is. It’s a pretty small delicate piece of equipment. Honestly, removing the faceplate to clean the IBTS is pretty simple and is likely easier than futzing with that small fan to do the same job.
As @walking_line said there is the IBTS fan inside the Control pedestal. And you have to remove the face plate for regular maintenance anyway. After other cleaning it’s easy to access the sensor with a Q-Tip+alcohol (after cleaning the view port with a separate Q-Tip!).