Below is an excerpt from a reply to a customer who asked the above question:
We have done a fair amount of testing with the FTSs system.
All of the testing was done with Water in the range of the mid 30's.
That's what you get when you put Ice Blocks in the cooler.
So, to answer your question. Yes you will be able to cool your fermenter
with water that is near 33F. That's not an issue.
The impossible part for us to answer definitvely is related to your
ambient conditions, details of your setup, and target temp. These will
influence the performance of the system.
We know that the typical temp rise of the cooling water is about 3-4F as
it travels to the fermenter (assumes you have ~2m length uninsulated
If your room temperature is 'moderate' you should be able to hold the
beer at 33F + 4F = 37F would be your absolute minimum temp.
As for the volume of water you need, again that is dependent on the
ambient temp and target them of the beer. In our testing we typically
used 5 gal of water. So, depending on your situation. . . 5gal is likely
You should insulate your lines with the black foam Pipe Insulation you
can buy at Lowe's or Home Depot. . . it's cheap, looks good and will
If you find your pump is running all the time, and you are not hitting
your temp. . . that would tell you that you need a bigger volume of