Proper Element Height in Boil Kettle

[TinTurtle]

I am looking to purchase a 20g boil kettle from Brewer's Hardware. Dimensions are 15 3/4 diameter by 25 1/14 tall.

I want to put a second 1.5 inch TC fitting on that kettle (and have them do it prior to shipping). I would like to be able to continue with smaller batches if I want, but I'm not sure how close I can get to the bottom without causing any type of issue.

 

[ryan_george]

I usually aim to have the center of the element ~2" from the bottom of the pot. I've never worked with TCs, so I can't comment on how that will affect the placement of the port.