"MET" Probe - ET2 or XT (Exhaust Temp) Slightly More Accurate Name?

[leftism]

Yes, My ET line is actually MET. I only warm the roaster for about 10 minutes, and it has worked good for small batches( the graph I posted was on a ~400gr batch with low fan throughout the roast) , maybe thats the reason MET is so low then?

Next time I roast 450gr> I will warm the roaster for a longer time, it probably would be better to have more energy stored with larger batches?

[SusanJoM]

Here is a profile of 15 minutes of warm up time with the perforated drum HUKY.
Followed by the roast itself.
And then  you can see that as soon as the beans get added and start carrying the heat around the drum and to the far side where the MET t/c is that the MET climbs and stays higher than ET or BT until just before the drop.

I'm not promoting this profile;  I'm just showing you why I think warm up time is particularly important with the perforated drum.

[JavaBuzz]

Hi Susan,

In those graphs, what is your fan set at during the warmup and roast? Also, how large of a bean charge did you use?

[SusanJoM]

My fan is always at 26 on the Variac, which according to some tests I did a while back is about 16% of my available fan power.     The warm-up was 5 minutes at  1.5 kPa; 5 minutes at .5 kPa;  5 minutes at .25 kPa  -- if I remember correctly....

And my current favorite load is 350 grams. 

[JavaBuzz]

Thank you for the info Susan. I think if I put my fan that low (voltage or percentage) it doesn't spin, but I'll have to test and verify that. Could be some of the fan models act slightly different to minimum power? I know if I leave my fan at 100%, it can actually start sucking beans up and out of the roaster (actually kind of nice for dislodging beans in-between roasts).

I'll have to try the less aggressive/more stepped kPa warmup that you do too. I've had trouble with the flame going out if I get much lower than .5 kPa though.

[SusanJoM]

This has been posted a few times, and I apologize if you have already seen it, but this is the relationship I determined between my Variac and my fan