Hi,
I'm wondering while reading through the excellent "ET/BT rates of change" tread if using a IR (contactless) measurement device could be used iso the classic thermocouple . I'm also assuming that my IRoast's glass is of a lower temerature then the beans so it could be possible to measure it? Would this works and if so, are results are accurate.

-Peter

I tried it without any success. Measuring through the glass ends up giving mostly the glass surface temp and trying to measure through the fill chute (Hottop) required me to get in so close that I was heating up the sensor head too much (and it was still inconsistent). Best I could do was to get a decent reading when ejecting the beans which is a little late to be very useful! Still haven't figured out anything else to do with the IR thermometer although it is pretty neat.

Rick

I think it depends on the roaster. I have a Caffe Rosto CR-100 which has a glass lid. I know I am not measuring the glass temp as the centre of the unit (heater top) gives a much higher temp than the beans. I am pretty sure the temp is reading low but it is quite consistent. I pick a location and always measure there.

I found washing the glass lid between roasts helps to keep the oil film from distorting readings.

I agree a true probe would be better but for now this is serving me.

What about using the breadmaker/heat gun roast setup? There is no glass in the way. What about the rapid movement of the beans? Also, if it is measures surface temps, could that be any real indication of bean temp (internal). I would think later in the roast the temps would be more equal, but earlier in the roast I would think the surface temps would be much higher than the internal temps. This is all just speculation on my part, but would be interested in hearing from anyone who has had success with this method.

Jason
With practice, surface temp. is plenty accurate enough. You can also take your planned roast profile into consideration with the readings. It can take a few trials to find the best probe placement.
IR works well with a straight shot if you can shoot it without too much meter exposure to the extreme heat. Through glass is marginal but maybe better than nothing.

Ed,

Thank you for the reply. I think it is worth a shot for $30. It will also keep me from having to drill through the bucket which would cause a problem when dumping the beans or attempting to stabilize a thermocouple in a mass of swirling beans. We shall see.