[pinchegil]

I am making an Imperial Saison using wyeast 3724.  Wyeast says to pitch at 90, and hold at 90, I live in Colorado so that is not easy.  Using a spare a spare PID, copper tubing, my old homer cooler, a bucket heater and a fountain pump, I made a recirc, heater for my old school blichman conical. A design flaw which has been corrected by adding a second PID, allowed the temp to spike to 105 for less an hour.  I started with 300 Billion active cells,  anyone have any idea how much damage might have been done to their vitality?  I don't think the beer will be affected as it was such a short period.

[reverseapachemaster]

Likely no harm occurred at all. At that temperature yeast remain viable although their ability to reproduce diminishes. Once the beer cooled back below 100 they will resume any necessary reproduction.