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The Fermentation Chiller Phase III

Given that the Fermentation Chiller Phase II was a little flimsy and built on a strict budget, in 2006 I reconstructed the Fermentation Chiller out a little more stout material. I used foam adhesive to sandwich 3 sheets of 1 inch Styrofoam in between two sheets of coated hardboard. After the pieces were set, I cut out everything on the table saw. All my edges were clean and square (this time) and the results speak for themselves.

The top and front are removable and held tight against foam insulation strips by industrial Velcro. The top is hinged (hence the handle), but the front just lifts out of the way for moving heavy carboys in and out. Since I’m writing this almost 2 years after completing this project, I can tell you that it works well even in the Houston summer heat. Yesterday it was 98 in the garage and 68 in the Chiller. Pretty good considering!

I reconstructed the heat exchanger box from the FCII (see below) to;

Improve overall airflow
Reduce the amount of air that was going around the heat exchanger rather than through it

The exchanger box has a fan on the bottom and a fan on the top. The fan on the bottom is a lower speed “circulation” fan that runs all the time. The top fan is a high speed “cooling” fan that comes on when the glycol pump does. Both fans are “puller fans’ meaning that both pull air from out of the exchanger rather than trying to push air into it. One other issue I hadn’t considered in the design is the amount of condensation produced by the near 0 degree glycol used for the coolant. After the first couple of uses the low speed computer fan on the bottom started to make some grinding noise and didn’t sound real healthy. I used a DampRid refillable moisture absorber to absorb the condensation and the problem has been reduced, but not completely eliminated. Unlike the previous design, I mounted the aquarium pump outside the chiller box on a small premade bookshelf I had lying around. I stuck it to the box with double sided foam tape. It still needs two power sources, one for the pump which runs off of 120VAC and one for the fans which run off of 12VDC. The only issue is that the thermostat controls both the high speed fan and the aquarium pump, which of course, run on the two power sources. I used a micro relay to switch the 120VAC on and off using the 12VDC (the fan power) as the signal to switch.

There is enough room inside for two 6.5 gallon carboys or a bucket and a carboy. That’s a batch of Merlot in the chiller pictured at right. I have achieved temperatures as low as 45 degrees F, but that is the limit of the thermostat control and is getting close to 100% duty cycle on the cooling apparatus.

Overall, I’m fairly pleased with the outcome of this project, but I’m already considering what’s next. I really want to get the glycol out of the freezer that my family puts food in for peace of mind. Granted the ‘fridge was purchased as a “beer storage unit”, that all changed when I bought the chest freezer to handle those chores. The glycol is in a water-tight container in the bottom of the freezer and the glycol lines go through the ice dispenser (see Phase II below) so a leak would be mostly contained, but still, it is glycol we’re talking about. I’ve seen pictures of an insulated plywood cabinet that some guy in Texas put an A/C window unit in with a Ranco controller. But I need to get the new (phase III) brewery finished first.

Phase II

This is a photo from Phase II of this project. The entire assembly is constructed from 1" Stryofoam sheets that were glued together in a sandwich.

The seals are held with masking tape (duct tape would tear the foam!) and it has very little structural integrity.

It is for all intents and purposes, the Phase I box with the guts taken out and replaced with the heat exchanger "assembly". The heat exchanger was constructed out of an oil cooler I bought a long time ago to add to the Ford Mustang that I had. I just never got around to actually finding a place to install it in the car and building all the braided lines to connect it.

So, when I started Phase II, I decided to use this oil cooler rather than stuffing the box on some shelf and forgetting about it again. Unfortunately, I had some severe design constraints and the results were less than optimal. The new design is more efficient and looks a whole lot cleaner too.