Fermentation Chamber

>> Monday, December 19, 2011

Update 5/29/2013: Unfortunately the chest freezer died. I'll soon be working on another one that will hopefully last a little longer. RIP Ferm Chamber 1.0

Here's my newest piece of equipment.  It's a chest freezer that I've modified to use as a fermentation chamber.  A while back, I realized fermentation temperature control was one area I was really lacking.  My HERMS brewing system provides for very accurate and repeatable mash temps.  Fermentation temp control is just as important as accurate mash temps when it comes to consistent repeatable results.  I have lagering ability but I've been lacking heating ability.

There are commercial heating solutions on the market such as the Brew Belt and the FermWrap heater.  My understanding is they work very well, but the only problem is I have a mix of fermentation vessels (conical, glass carboy, bucket, Better Bottle) and none of the commercial products seemed to work for all fermenters.  Considering  my needs, a fermentation chamber seemed to be the best option.

I found a used Haier 7 cubic foot freezer on KSL classifieds for $50.  Seemed like a bargain since it has built-in cooling capability and it is well insulated.  For heating capability, I went with the Brewer's Edge space heater from Williams Brewing.  This is essentially a heating pad/mat that sticks to the side of your fermentation chamber.  It takes up zero space inside the chamber and it's only 25 watts so it should cost next to nothing to run.  It's advertised that it can keep a small space up to 20 F warmer than ambient air temps.  I tested it with a five gallon bucket of water and it actually exceeded the advertised capability; it held 70F in an unheated garage with overnight lows in the high teens and low 20's.  I may pick up a second one as extra insurance against very cold nights.

To control the heating and cooling cycles, I built a controller based on the eBay aquarium temperature controller.  Its functionality is well documented on HBT, so I won't go into too much detail here.  These work great and it's the cheapest dual stage controller I've come across.  The only con is for us in the US, these only display the temp in Celsius  This can be easily remedied by making a chart to convert between Celsius and Fahrenheit.  For anyone interested in building one, here's the link to the thread on homebrewtalk.

I needed a little extra height inside the chamber to accommodate my conical fermenter so I built a collar similar to what you'd typically see on a keezer project.  I decided to use a PVC fence rail for this because PVC is a good thermal insulator and I shouldn't have to worry about rot, painting, warping, etc.  I used some PVC angle to reinforce the corners.  I also made some some simple wooden L-brackets to fit inside the rail to further reinforce the corners and provide a secure mount for the relocated hinges.  For adhesive, I went with Plumbing Goop Contact Adhesive & Sealant.  I was hoping to find something that would essentially weld the joints and form a strong permanent bond.  I couldn't find anything like that but this Goop product seemed to work fairly well.

I mounted the collar using double-sided tape and caulked all the joints/seams.  I also caulked the corners of the freezer interior.  I did this for sanitary reasons just in case I ever have a messy fermentation (I don't want anything funky growing in the corners).  The collar was then insulated with two layers of 1" rigid foam insulation.  I also used some aluminum foil tape to help seal joints/crevices in the foam.

Lastly, I welded a dolly for the fermentation chamber so I can easily move it around the garage.  To minimize lifting, my plan is to clean and sanitize the fermenter, put it in the chamber, then pump cooled wort directly from the boil kettle into the fermenter.

I haven't added it yet, but my plan is to add a fan and some ducting that will constantly circulate air in the chamber.  This will help ensure consistent temps without stratification.  I haven't had a chance to ferment in it yet, but it seems to be working very well.  After finishing it up, I've been testing it with a 5 gallon keg filled with water with the temperature probe taped to the side and insulated with a piece of foam.