Raising fan speed raises temperature

[Morrowless]

Every time I raise my fan speed, I see a visible spike in RoR as well as BT/ET. That seems rather counter-intuitive... did I screw something up? I'm using Gregr's Rao curve guide, with a variac.
How can I eliminate this spike?

[edtbjon]

That is because the added airflow past the burner makes it (the burner) more effective. This is especially true for the beginning of the roast where I normally use high heat and minimal (but a little) airflow. The burner is running too rich and could (and eventually does, when you speed up the fan) benefit from more oxygen.
For the last part of the roast, when you are using a low burner setting, speeding up the fan to a high setting does indeed slow down the RoR
While it can be interesting to make a series of test roasts trying to find out more about airflow and how it affects the roast (i.e the roasted beans), I've since long been using three fixed settings, lo - mid - hi, which works for me.
If you're concerned with that spike, try to lower the heat setting some 10 seconds before going from e.g your low fan setting to the mid fan setting. Adjust to taste...

[Turboner]

"The burner is running too rich and could (and eventually does, when you speed up the fan) benefit from more oxygen."

I am not sure I agree with this 100%. I have tried keeping the heat source steady and raised the fan incrementally where the temperature would go up, but then hold steady, and eventually cool down.

Cat and cloud covered this in one of their podcasts and they mentioned that the fan draws the heat of the drum itself.

What I had deduced from what they had mentioned is that, at a certain fan speed based on the heat coming from the burner, the fan is drawing the hot air/hotter air heated by the drum. At a much higher fan speed and lower burner temperature, the drum is not able to heat the air as quickly therefore the air being drawn is "cooler". This is especially obvious in a roast profile like edtbjon/Ggregr. Where when you drop the roast, turn off the burner and then turn the fan from a high setting to a low setting, the temp will drop slightly and then slowly inch back up but then drop again since there is no heat source on the drum.

I could be wrong though hehe, my theory does seem like it has a lot of holes.