This is what I like to think of as a novel design for a wort chiller. I have seen commercially available chillers that were encased in PVC canisters like this, but I do not know what's in the canister other than copper tubing. It was therefore necessary to reverse engineer the design.
The philosophy behind the design is to maximize the surface area to volume ratio of the copper tubing containing the wort, use a baffle arrangement such that the cooling water closely follows the wort tubing, and minimize the volume of water not in close contact with the wort tubing (cooling water dead volume).
My chiller design has the usual copper coil: In this case 20 feet of 1/4 inch OD soft copper.
The design is unique by virtue of the plastic baffles which channel the cooling water in a spiral pattern to closely follow the copper tubing. It took some days to envision a system by which the flow path could be channeled. This design came to me one morning while I was in the shower! You may picture it as a screw, or inclined plane.
Here the plastic baffles are being loaded into the copper coil. The slit in the baffles allows them to join edge to edge to form a continuous spiral enclosing the copper tubing. The blue circle is a thicker plastic baffle which was used to hold the tubing coils apart while the baffles were loaded.
The center hole in the baffles provides space for a length of 2 inch PVC tubing. The purpose of this tubing is to minimize the dead volume of the chiller. This should assure that the cooling water flowing through the chiller remains close to the copper tubing at all times.
Two inch PVC caps were sawn in a spiral pattern to match the end baffle and tubing of the wort chiller.
The 2 inch PVC tubing was sawn to length with just enough tubing poking through the end baffles to allow a snug fit with the caps. The spiral notch on the cap prevents the baffles from rotating and opening up gaps.
The completed coil/baffle assembly.
The coil/baffle assembly is being loaded into the PVC shell.
The coil/baffle assembly is positioned at the correct depth to allow installation of the end cap.
Care was taken to make sure that the tubing emerged from the center of the assembly.
Four inch PVC caps were drilled in the center with an 11/16 inch bit and threaded with a 1/2 inch MIP TAP.
The caps were then drilled between the center hole and the edge with an 11/16 inch bit. This was a bit awkward.
These holes were also threaded with a 1/2 inch MIP TAP.
Teflon tape was applied to 1/2" MIP hose connectors and MIP-1/2" compression fittings.
And installed on the caps.
The 4" PVC shell was cut to length and the end caps installed. 1/4" to 3/8" female adapters and male 3/8 copper barb fittings were then installed on the 1/4" copper tubing.
The original plan was to bush the 1/4 inch copper up to 1/2 inch copper before it exited the end caps, hence the 1/2" compression fittings. This did not work as well as planned, and 3/8 plastic tubing was used to seal the 1/4" copper tubing in the central cap fittings. It seems quite snug.
This is the finished chiller with its stand. The stand will be discarded if/when I make a brew sculpture. I'm still thinking about it.
In actual brewing the following numbers were observed:
The wort was sent through the chiller by gravity. Max drop was 42 inches and minimum drop was 15 inches which accounts for the long cool time. Obviously I need to have more fall or pump the wort.
The only problem noted was minor leaking at the copper tubing's end cap brass fittings. They have since been resealed with clear silicone sealer.
I'm thinking about making a conventional chiller for the BK and running this chiller's exit water through it. No sense wasting all that nice 24 C water.
Performance exceeded my expectations. I'm very pleased. Next brew date is 1/24/09.
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