In a previous thread, https://www.homebrewtalk.com/f51/immersion-chiller-upgrade-redneck-fermentation-252421/ , it was suggested to split the incoming water and have it go to each coil, parallel. I had it set up for the water to go from one coil and into the second, series. I said that I would test the chiller both ways and had time this afternoon to do it.
https://www.homebrewtalk.com/attachment.php?attachmentid=28170&stc=1&d=1308793107
https://www.homebrewtalk.com/attachment.php?attachmentid=28171&stc=1&d=1308793245
Here are the details of the test.
I brought 10 gallons of water to boil in a keggle outside and it was 87 degrees.
The water temp out of the hose was 62.5 degrees.
I started cooling once I had a roiling boil. I took the temp at 10 minutes, the time at 90 degrees, and the time at 80 degrees.
Series,
After ten minutes, 102 degrees
90 degrees 12 minutes
80 degrees 17 minutes
Parallel
After ten minutes, 106 degrees
90 degrees 14 minutes
80 degrees 18 minutes
So it came out that series worked better in this case than parallel. So if you have a 25' immersion chiller adding a second coil can really improve cooling.
https://www.homebrewtalk.com/attachment.php?attachmentid=28170&stc=1&d=1308793107
https://www.homebrewtalk.com/attachment.php?attachmentid=28171&stc=1&d=1308793245
Here are the details of the test.
I brought 10 gallons of water to boil in a keggle outside and it was 87 degrees.
The water temp out of the hose was 62.5 degrees.
I started cooling once I had a roiling boil. I took the temp at 10 minutes, the time at 90 degrees, and the time at 80 degrees.
Series,
After ten minutes, 102 degrees
90 degrees 12 minutes
80 degrees 17 minutes
Parallel
After ten minutes, 106 degrees
90 degrees 14 minutes
80 degrees 18 minutes
So it came out that series worked better in this case than parallel. So if you have a 25' immersion chiller adding a second coil can really improve cooling.