When it relates to heat exchange, copper is a better conductor of heat over stainless steel. Using a copper immersion chiller will cool your wort faster, produce a better cold break, and halt the isomerization of alpha acids (locking in your hop profile) at a faster rate. Then why make a stainless chiller? We'll dive deeper into their advantages and disadvantages below.
Copper Immersion Chillers
Copper is the standard material for immersion chillers because of its ability to transfer heat. 3/8" and 1/2" OD soft copper tubing is most widely used and which diameter you choose will depend on the batch size.
- Highest heat exchange rate
- Easy to manipulate
- Is easily soldered, welded, or brazed
- Copper will develop a dull stable oxide layer over time that is resistant to corrosion in wort
- Minimal cleaning is needed to remove hop residue, wort protein, and surface grime (no need to clean copper to shiny bright)
- Copper and other trace minerals are good for the yeast
- Copper can develop a green-blue toxic oxide called Verdigris (i.e. the natural patina on the Statue of Liberty) if not stored in a dry environment. Verdigris is water soluble and can contaminate your brew if left on your chiller before immersing it (easily cleaned with an acidic solution like StarSan or Vinegar).
- Not as rigid as Stainless Steel
Stainless Steel Immersion Chillers
Relatively new on the scene, stainless steel immersion chillers have gained popularity in the market because of rising cost of copper. Stainless steel chillers can now be purchased for the same cost as a copper chiller of similar dimensions.
- The gold standard of brewing equipment
- Excellent corrosion resistance
- Easy to keep clean
- Very rigid and will last a lifetime with proper care
- Hard to manipulate
- Not as efficient as copper leading to a weaker cold break and longer isomerization of hop alpha acids.
- Does not leave behind beneficial trace minerals for yeast
The chiller you choose will be a personal choice and you can't go wrong with either one. But in our professional opinion, when it comes to chilling a 5-15 gallon batch of wort, nothing comes close to the efficiency of a properly sized copper immersion chiller.