I was reading the article posted by Peter Cotton on his no chill brewing. I had no idea of just how the water restrictions in Australia could affect home brewing. I personally have been doing an ice bath for years, but wanted to move up to an immersion chiller to quicken the cool down to reduce my brew day. Peter’s methods works for him but there is a lot of work, cost and time delay involved. I recalled conversations of friends in South Carolina who had issues with the ground water being too warm to be effective. Plus there is all that water that goes to waste. There had to be a better solution, so I had a home brew and thought about what I could do that was compact, cost effective and efficient.
Building the Cooling System for Your Wort
First I decided an immersion chiller over a cold plate was for me. Less cleaning, hassle, and if you make it yourself, a significant cost reduction. A 20ft coil of 3/8 soft copper tubing is less than $15 at a Big Box Store, maybe a bit more at a home improvement store. It’s already coiled so half the work is done for you. Simply take out the coil and hand separate it into a long slinky type thing. I slipped it over a paint can and hand tightened the coils up to make a pretty good facsimile of what you buy in your LHBS. I then took a copper tubing bender to make the 90degree bends. If you don’t have one, then another trip to your Big Box Store can get you a Brasscraft tube bender that does 3 sizes for less than $13. Slip some 3/8 nylon tubing over each end, hose clamp it and you are done (and remember to check your hose clamps before brew day).
Above left is my Homemade Immersion Cooler, and the Right is one from a LHBS. The store bought one is $70 and I made mine including tubing, clamps and hose for less than $18. If you don’t have a bending tool you can borrow or purchase one. I purposely expanded my coils to get more surface area available which is why it looks a little different than the LHBS one. If you want to get technical, you can focus the most of your coils as the top for maximum cooling efficiency.
How the Recirculating Immersion Chiller Works
Notice mine does not have the faucet ends and we won’t be needed them. We will be recirculating chilled water so there will be no waste. The idea is simple-take a cooler and put in a submersible fountain/sump pump. Fill the cooler with water and a bunch of those re-freezable blu-gels that you use in a lunchbox or cooler. This cuts down on the water needed and helps to maintain the water temp. Now you also have a reusable source of “ice” for your chilling water. The pump outlet goes into one of the immersion cooler tubes and the other immersion cooler tube will go back into the cooler. Turn the pump on and cold water goes from the pump into the immersion cooler in your kettle and back out into the cooler. The hot water goes back into the cooler and if you have enough blu-gels the water will be cool enough to quickly and efficiently bring the temp down in your wort.
Have the Right Pump
This is all fine and good but what about the pump? It needs to be water proof, have the GPM required to do a decent heat transfer, have enough Maximum Head Lift in order to work. Maximum Head Lift is the height the pump can move the water above the pump. This is important especially if you have multiple tiers in your brew system. If you go above the maximum Head Lift, the water will simply not pump. So this was the one item that could be costly enough to not go this route. Fortunately, Harbor Freight is your friend, and while their tools may not be suitable for professional or everyday use, you can however get a lot of value in what they do have. I purchased a Pacific Hydrostar fountain pump at Harbor Freight for $16. It is water proof, can pump at 264 GPH and has 4.6ft of head lift. This means that the pump is capable of pumping water 4.6ft above the water level which is plenty for my purposes.
Answering the Questions
So can this cool down liquid from a boil to pitchable temp? Will the cooler water become too warm from the heat transfer? Will I have to add ice or more frozen blu-gels? And finally will it be quicker than an ice bath? The only way to find out was to test it. For the test I used my Thermoworks Smoke dual probe digital fast read thermometer and a kettle with 4 gallons of boiling water. Because of the outside temp being below freezing I choose to boil on my stove and use indoor temps to not have the outdoor ambient temp affect the test results, which is why I only used 4 gallons of water. I used one Probe in the cooler to monitor the temp rise and the other in the kettle to monitor the temp fall. Here is what I found out.
After 1 minute the wort was 165 degrees and the cooler was 42 degrees.
After 8 minutes the wort was now 98 degrees but the wort was 79 degrees.
At this point the thermal energy from the wort to the cooler was slowing due to the rise in the temp of the cooler. I should have swapped out the blu-gels for frozen ones to bring the cooler temp down. But since I had not frozen any more I continued to see how far I could go with this diminished heat transfer.
At the 13 minute mark the wort was 89 degrees and the cooler was 78.
There was no more thermal energy that could be passed in a reasonable amount of time at this point. I believe if I swapped out the blu-gels when the water was above 50 degrees I could cool the wort to pitching temperature in less than 10 minutes only using a total of 5 gallons of water. If I found a more efficient cooler like the 5 gallon igloo one I used in a previous article, I believe I could pack more blu-gels due to the container being taller than wider, and use less water to still cover the blu-gels. When I was done with the experiment I put the water in my rain barrel to be used to water the plants in the yard. In my opinion the experiment was a success. I will have to try it with a swap out of the blu-gels and my new kettle with the tangential whirlpool port which will circulate the wort for better thermal transfer.
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