It seems that in my recent post looking at Harold McGee's technique for delaying and diminishing berry mold, I made the situation a bit more complex then it seems it needs to be. In a personal communication, posted here with his permission, Harold wrote to me:
"Hi John, thanks for this, and glad to hear about the cvap solution! But
I would never suggest a method in the Times that required an immersion
circulator, which a vanishingly small proportion of readers would have
access to. I was just writing about a pot of hot water and a
thermometer. The temperature change in 30 seconds is minimal, and the
exact temperature isn't that critical. Anyhow, nice to hear from you,
and hope our paths cross again one of these days– Cheers, Harold"
The CVap worked and an immersion circulator would no doubt work, but McGee's experiments used neither. While I will continue to use the CVap for this purpose as it does offer some advantages, there is no need to reinvent the wheel!