I have been looking at your software and find it very impressing, not the least the rate of upgrade/improvement. Now I want to buy a digital thermometer and try it out . Which device on your list do you recommend? I have also been searching for information on best location of the BT and ET temperature probes but can not find any. I have a 1kg Toper Cafemino Gas, any suggestion on placing the probes?

Hi Rurano.

I am not familiar with your roaster. So this is a guest.

The BT (bean temperature) should be ideally just above the bean level. If is is higher, it is OK. So fill up your drum with the max load and find the height level of the BT thermocouple. Then chose left-right (away from tryer) and drill a hole (you may need a tap-die set and and a thermocouple adapter). Or use your current thermometer hole if you have one.

For ET you want a compromise between a fast response from changes in heat input and also a fast change in BT (think as output). The closer to the heat input the faster heat input the response. The closer to BT, the faster the BT output response. Depending on your roaster, the best place may be next to the drum surface externally (but away from the flame, maybe on top). Using Et as the outer drum surface temp may be a good idea.

I am sure there are better ideas, but before you drill anything, try different spots. Hopefully someone else will tell you better.

Cheers

Raphael's concept are sound and may be very applicable to a Quest but I have to ask:
Why would you put the BT just above the bean mass? I always put the BT probe well inside the bean mass not too close to any metallic surface to bias the reading.
If you put the probe above the bean mass you measure the air temperature? That, in my understanding (which is not great by any measure) is ET. Isn't it?

On my Cafemino (electric), on the suggestion of Chris, A.K.A. Gyro, I have installed a probe that goes through one of the sight glass screw holes. Pictures of Chris installation here:
Help with Roaster PID please
I have found that the readings are ok at that location with loads as low as 250g. Still experimenting with length, depth and location though.

I have an ET probe just above the drum on top going through one of the charge fitting screw. I have another that goes inside the exhaust tube upstream of the damper. Of course there is the standard Cafemino probe. I am not happy with any of these location and I am still trying to find a good one. I am not controlling any loop with these, just monitoring.

Any help would be appreciated. All this experimentation is resulting in a lot of wasted and less than great tasting coffee. I am not complaining just asking for help in reducing my slow learning curve.

Whale wrote:Why would you put the BT just above the bean mass?

I am not sure. I thought I read it somewhere. It may be that the beans are moving.

Whale wrote:If you put the probe above the bean mass you measure the air temperature? That, in my understanding (which is not great by any measure) is ET. Isn't it?

I am not sure. If they are only apart by 20-30 degrees or so, then I think ET would not give much of an indication. ET would be like a second BT. An important temp you want to keep an eye is the drum surface. If it gets too hot, beans scorch (not right away, but over long exposure). It is also a good mid point between heat input and bt output.

Cheers

Whale wrote:Why would you put the BT just above the bean mass? I always put the BT probe well inside the bean mass not too close to any metallic surface to bias the reading.

I agree to Whale here. My BT probe is placed such that it is in the bean mass, also through one of the sight glass screw holes with the probe slightly bent. The ET probe is as much above the bean mass not to be influenced by the bean temperature but measuring the air temperature above the beans. I have put my ET probe inside the drum close to the axis (but a bit lower) in its center.

M.

MaKoMo wrote: My BT probe is placed such that it is in the bean mass, also through one of the sight glass screw holes with the probe slightly bent. I forgot to mention it.

My probe is also slightly bent down.

MaKoMo wrote:The ET probe is as much above the bean mass not to be influenced by the bean temperature but measuring the air temperature above the beans. I have put my ET probe inside the drum close to the axis (but a bit lower) in its center.

The Cafemino has a probe in the approximate same location. I find that it measures the air going through the drum pretty well, with a little influence from the bean mass though. I have a probe (that I did not mentioned before) that is installed at the rear end of the drum and measure the air going in. In a steady state condition the temperature of the air going in is always higher than the air coming out.

Arpi wrote: An important temp you want to keep an eye is the drum surface. If it gets too hot, beans scorch (not right away, but over long exposure). It is also a good mid point between heat input and bt output.

This is my understanding and the object of my previous question. All the ET probe locations that I have and tried are not giving me an good enough indication of the drum temperature that I would feel confident of. Short of a contact-less IR thermocouple I do not think that I am gonna get it.
I am not saying that I need to know because I am not getting any superficial scorching or any tipping at all.

Thank you very much for the replies I must admit however that I am not completely clear about BT and ET and the placement of the probes. My logic says that the ET should be the measured air temperature inside the drum close to the mass of beans (the temperature that "works" on the beans) and the BT the "more actual temperature" inside the mass of beans. Am I completely lost here? Is it not the temperature state of the beans and the energy we are about to expose the beans to we want to measure?

Maybe I can use the original temperature probing point (Toper probe) for the ET? The original Toper probe is not very accurate (I usually get FC arount 173C) and it is used to automatically turn off gas supply at a set temperature (around 195C). It is shown in the picture a little above center to the right. Or maybe in the bolt hole just above the center?

Is a 4 channel datalogger required to include delta ET and delta BT?

Is a 4 channel datalogger required to include delta ET and delta BT?

The delta ET and delta BT are computed from the ET/BT probe data. No need for a 4 channel logger for this. By now Artisan supports only 2 probes. This might change..

M.

If I had to select a data logger today, based on the latest hint that the Artisan could some day track more than 2 inputs, I would get a Center/Voltcraft/Omega/Sperscientific/Tecpel 4 channels Data Logger.

Even if the Artisan never allows 4 channels monitoring, having the other data inputs would be interesting to me.
This way one could monitor; BT, ET (one or more), External (lab, garage, outdoor) temperature and Exhaust air temperature for example.

Marco,

I am having difficulty getting the Omega HH806AU to communicate with my MacBook Air using the new version. It refuses to talk across the USB port. Any advice???