Chill Out, Man

One of the most important steps in brewing is cooling the boiling wort to a temperature where yeast will flourish and bacteria will not. The two primary devices available to homebrewers are immersion chillers—copper loops carrying cold water through your wort—and counterflow chillers, which run the wort through copper tubes while passing cold water along the outside of the tube in the opposite direction.

When we upgraded from stove-top five-gallon brews to our outdoor ten-gallon system, we bought a counter-flow chiller to replace our immersion chiller. My understanding at the time was that the CFC was a more efficient and faster chiller than the immersion chiller, with the downside being that you must be more careful about sanitation (since you don’t have direct access to the surfaces that the sweet wort contacts, it’s harder to ensure that there are no pockets of debris that might harbor bacteria).

The last few brewing sessions have left me frustrated with our chiller, though. In order to get the temperature drop I want (ideally to 68-70F), I have to run the wort extremely slowly out of the kettle, while running the hose at near-full blast. Yesterday’s beer took over 45 minutes to rack off into the carboys. I haven’t done the math on flow rate of our hose, but it’s a sub-optimal use of water, since we don’t have a good way to catch and reuse it. Any faster flow of wort and we get carboys full of 78-80F wort, which is begging for strong yeast esters and, worse, bacterial competition for our hard-earned sugars.

There are several possible solutions here: a longer CFC would probably help (ours is 25′); there are also better CFCs out there than our generic one—they cost more, and use twisted square copper tubing to perturb the flow of wort and coolant and ensure that the hottest wort comes into contact with the coolest water. But I think my next effort will be to use the equipment we already have, and use both the CFC and our old immersion chiller, running the water output from the former into the input of the latter. This will be a bit more effort, and we’re going to have to handle our waste water more carefully (the output of an immersion chiller can be close to the temperature of the bath it’s in, which is to say: nearly boiling), but we should be able to cut down our water use significantly.

If anybody out there has experience with counterflow chillers that are underperforming, I’d love to hear how you solved the problem.



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