Another BrewGarage Project

I blew my keg of Classic American Pilsner the other day, and I began to lament the impossibility of replacing it any time soon. It has been one of the hottest (and driest) summers on record here near Seattle, and lacking a fermentation chamber or truly practical space, brewing lagers is out of the question for the foreseeable future.

Or is it?

My beer fridge is set to normal refrigerator temps (around 34°F). I could raise that up I suppose, but that would affect other things (like having cold bottled beer or the hops stored in the freezer). My keezer is set at 48-50°F, which is a little on the low side, but doable. The problem there is that putting a fermenter in there either takes up keg space (again, less beer) on the floor, or requires jury-rigging on the compressor hump (in order to have airlock clearance).

However, I began to think I might be on to something with the keezer... What if there was a way to harness the cooling temps from it without taking up space inside it? Like some kind of heat exchanger? Based on that idea, I turned to Google.

I really could not find anybody doing anything quite like what I had in mind. I was picturing a copper manifold hanging against the wall of my keezer, circulating water from cooler or garbage can by using a pond pump; the fermenter would be immersed in the water within that cooler/garbage can. This would be a very low-tech/low-cost environmental control: by keeping a larger thermal mass at lagering temperatures, the beer temperature could be held more steady and cool enough to brew a lager.

The closest thing I could find was where James Spencer (@basicbrewing) discusses using a pond pump to circulate water from an ice bath (he calls it "Low-Tech Lagering" [Basic Brewing™ Low-Tech Lagering and Decoction Mashing DVD] or "Easy Lager Chilling"). I have a Ranco ETC controller, but didn't want to mess with the ice or frozen bottles.

Since I couldn't find anybody doing it the way I envisioned, I felt it was worthy of experimenting at the very least. My total cost turned out to be less than $50US.

Parts:

• cheap submersible pond pump (I went with the 155gal/hr model <$20US)
• ~15' soft copper tubing, 3/8"OD
• 2x 90° copper elbows
• (1x copper slip connector - I spliced a 10' tubing section with a 5' section)
• copper pipe hangers
• 3/8"ID vinyl tubing
• hose clamps
• propane torch
• water-soluble flux
• silver (lead-free) solder
• spring tubing bender
• copper pipe/tubing cutter
• hockey puck
• fabrication mock-up/template

When I am fabricating, I like to make mock-ups or templates on cardboard or on my work surface. I have found a few minutes building a template helps me visualize how the fabrication will unfold, allows me to troubleshoot a bit before I begin, and saves me time and materials in the long run since I invariably would screw something up without one. In this case, I took measurements inside my keezer to insure length/width fit, as well as the proper placement of the inlet/outlet tubes at the top. The dimensions of the main portion of the manifold are 24" wide x 15" tall, with all primary curves of 3" diameter.

I straightened out my coil of copper (using the spring tubing bender). I began construction at the top of the copper manifold (bottom in the picture above), using the spring tubing bender to form my curves around my hockey puck; the hockey puck is a perfect form, since it is hard rubber and has a 3" diameter. That first 90° bend was no problem, but when I got to the first 180°, I hit my first snags...

Tools:

First, (and I should have already figured this out, being a math teacher!) using a 3" form actually results in an overall diameter greater than 3"; my template was built with an OC/overall diameter of 3", but in reality I was going to gain 3/8" with each turn. This immediately messed up my project scale. Second, 3" is about the tightest inside diameter that I could bend with the spring tubing bender, and it was a HUGE pain to work the spring around the curve!

I was able to overcome the second problem with sheer stubborn determination (and very sore fingers/hands the next day)... As far as the over-sized curves, I did some quick estimates towards the final project dimensions, did some measuring in my keezer, and initially decided to proceed and end up with a square-ish manifold. In the end, I was able to "overbend" the 180° curves to get back close to my original project dimensions; the cross tubing was not parallel or horizontal - not "pretty" - but that was fine with me... It goes inside the keezer where very few people will see it anyway! I added some rigidity to the manifold by soldering on copper pipe hangers. Then I took measurements with the manifold in place inside the keezer for proper inlet/outlet placement (getting them around the backs of the taps required careful placement).

It ended up fitting pretty well (and looks less ugly in the keezer). 

I filled a 32 gal garbage can with 5 gallons of RO water and installed the pump. Once the tubing was all hooked up, I started running the system. The H2O temperature started at 68°F, and the garage temperature was about 69-70°F. The manifold cooled immediately upon installation (I guess that's the nature of a heat exchanger!), so I'm cautiously optimistic about the system's ability to cool and maintain steady temperatures. I will collect some data, and update the blog once I have real numbers. Once I have that data, I might hook up the Ranco controller to the pump...

This is really just a temporary (quick/cheap) solution for maintaining lager brewing temperatures. Bigger projects I am planning include temperature-controlled fermentation chambers (heating and cooling) with Arduino/RasberryPi driven temperature control.