Regarding the earlier discussion of calorimeter sensitivity, the increase of voltage to the blower fan from 8.55 V to 10.45 V results in almost exactly a 2 W increase in fan power consumption, which is easily discernible with a 0.2 C delta T increase (at this low inlet air temperature).
Keep in mind that the air velocity has also increased, so the delta T at the old air velocity (basically impossible to test) might be higher.
The fan is currently consuming 5.8 W, which leads to a 0.45 C delta T.
So it is remarkably sensitive.