We sell optional coil extensions that just go between the existing coil and the FTSs lid that drop the chiller coil further into the fermenter body for those of you who would like to do for example a 5 gal batch in a 14 gal Chronical.
Take a look at the following link to view them on our site. Extension Coils
Below you'll find the MINIMUM batch size required to still have the immersion coil(s) fully submerged in your beer while using the OPTIONAL extensions available on our website for those of you that want to do partial batches.
Half BBL > 7 Gals
14 Gal > 5 Gals
7 Gal > 3 Gals
3.5 Gal > 1.5 Gal (3.5 Gal Brew Bucket NOT compatible with extensions)