I’m looking into buying an immersion chiller, and I’m wondering what benefits copper has over stainless steel.
Copper will conduct heat better than SS. SS is more durable and likely less expensive than copper these days. If you’re handy you can build your own with copper for less than either would cost pre-made.
I bought stainless, and though it is the only chiller I have had, I have had nothing but good luck with it so far.
I’d recommend getting a counterflow chiller. I just switched to one from an immersion and it is great. Cools to 70F instantly while siphoning from the boil with just tap water.
Copper does conduct better than stainless, but for the purposes and length of a wort chiller, there will be no noticeable or appreciable difference in performance.
Stainless will be easier to keep clean, in my opinion.
I use a SS chiller, but went to Lowe’s and bought a 10’ section of copper of the same diameter to make a pre-chiller which I place in an ice a bath and just connect with some tubing. (I wrapped the copper tubing around a corny keg to make the coils). The pre-chiller makes a big difference, and it will cool wort in 5 minutes or so.
Not as efficient as a counter-chiller, but still pretty good.