This is an interesting question that I have found myself asking lately.
I rant the first test through my cabinet with the following conditions.

I used a Coopers ‘kit and kilo’ kit of their Sparkling Ale.
It was mixed as per instructions to make up 23l.
BEFORE pitching the yeast I took 11.5l out into a second carboy.
Yeast was divided and pitched.

One carboy sat on my garage (I mean brewery) bench, while the other went into the fermentation cabinet set at 22 degrees C.

over the week long first fermentation cycle the ambient temperature brew ranged in temp from a low point of 16 degrees to a high point of 28 degrees C, while the fermentation cabinet brew has a low point of 21.8 degrees C and a high point of 22.2 degrees C.

Obviously the theory goes that if the temp is uber consistent then the yeasties will have a good regular chow down, whereas if the temp varies then they will eat a bit, rest up a bit, then chow down vigurously.

Note, I did say theory there!

So, 1 week first ferment, then bottled. I numbered the bottles as they were drawn off from the carboy so that I know where in the batch each bottle is from. Into the garage brewery cupboard for 4 weeks and we are ready for a blind taste test.

Bottle number one fermentinator and number one ambient are chilled for a day then we are ready for tasting.

two taste testers both handed an A and a B glass and both were unanimous that one beer was far superior to the other.
The only issue was that the superior beer was the ambient temp fermented one.

So what went wrong?
Was that $400 or so down the drain on fermentation temperature control?

Well, I dont think that anything went wrong as such as there was absolutely nothing wrong with the fermentinator batch, just that the ambient fermented batch was much better. That tells me that the fermentination cabinet could churn out that same beer time and time again, while I may never get the same temperature ranges for the ambient brewed beer.

I am not actually upset at the results. Well I have 10 or so bottles of a really fantastic beer to dring and the same of a pretty good beer to drink

Where the fermentinator comes into its own though is Lagers. The Pilsener that I now have in secondary in the fridge could never have been first fermented without the fermentation temperature control cabinet. It sat for 1 week at 15 deg and 2 weeks at 10 deg C while ambient temps got as high as 30 deg on one occasion.

That experiment will take to Christmas to come to fruition but I will continue to use the cabinet for all the brews that I put up from now on, making for easily repeatable results.

Stay tuned for the next installment on how I made a 4 channel temp logger with internet based graphing so that I can check the Ambient, Carboy, Internal heatsink and External heatsink temps from anywhere with an internet connection…..