Son of A Fermentation Chamber Detailed Plans

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I started getting into home brewing as well as wine and mead making recently. An important component of that is keeping the liquid at the proper temperature during fermentation. I heard about the "Son of a Fermentation Chamber" online but the original page was gone. I decided to provide detailed instructions to build a Son of a Fermentation Chamber myself.

What is a Fermentation Chamber?

It's a box, cabinet or closet used to maintain a consistent temperature for fermenting liquids such as beer, wine or mead. It's usually comprised of an insulated chamber with a method of cooling or heating the air in the chamber.

Son of a Fermentation Chamber Benefits

The Son of a Fermentation Chamber (SOAFC) is a very easy to build and inexpensive fermentation chamber you can build from easy to obtain components. The main body of the cabinet is just 2" Rigid Insulation that you can get at your local hardware store. It requires minimal tools and skill to build.

It uses ice, usually frozen water in gallon jugs, to cool the space as well as a small PC fan and thermostat. Since fermentation generates heat and the SOAFC will usually be in a conditioned space of your home cooling it down to fermentation temperatures is more often required instead of heating.

What You'll Need



  • Long thin knife to cut insulation (sharpened putty knife works)
  • Long straight edge
  • Caulking gun
  • Tubing Cutter or hacksaw to cut pipe
  • Miter saw or biter box to cut dowels and wood quickly
  • 1/2" chuck drill, optional
  • Clamps or 2" Painters Tape

Cut List


  • 18 3-1/2" lengths of 1/2" dowel

Copper Pipe

  • 18 2" lengths of 1/2" Copper Pipe
  • 18 1" lengths of 1/2" Copper Pipe

1x1 board

  • 2 24-1/4" lengths and
  • 2 28" lengths of 3/4" x 3/4" (1x1) S4S board

Rigid Insulation

  • 3 28" x 16"
  • 2 29" x 32"
  • 2 29" x 16"
  • 1 7" x 24"

Cut Plan

Step 1: Cut Foam Shapes

Use a thin sharp knife or sharpen the edge of the putty knife along with a long straight edge to cut the insulation to the required shapes as shown below.

For the Internal Divider you'll need to make some additional cut outs to allow for airflow, the fan and the wood strips.

Cut a 4-3/4" x 4-3/4" square out of one of the top corners. Cut a 3/4" x 3/4" notch on the other top corner that will allow the 1x1 to fit in it. At 9" Make a second cutout that will fit your 120mm fan. Use your fan as a guide.

Ste 2: Make Holes For In Sides

The top and the front of the fermentation chamber are removable. They're held in place by wooden dowels through holes in the sides. To reinforce the holes we'll use 1/2" copper pipe.

Mark out the location of each hole on each side.

The easiest way to do this is just to use the 1/2" copper pipe itself to make the holes. Lay the foam on a worktable or other flat, hard surface that you don't mind getting scratched up like garage floor or over some scrap plywood. Twist a scrap length of pipe into the foam. It will cut it's way through. If you can carefully pinch one end in to get it to fit in a drill chuck you can use it as a drill bit to make the holes.

Note: Do not insert the 2" pieces of copper yet.

Step 3: Attach Sides

Spread a good amount of Liquid Nails Fuze-It along each side of the Bottom piece and attach the sides to the bottom. Do this on a flat, level surface. If you have big enough clamps use them to hold the sides in place other wise you can use some thick painters tape to hold the sides to the bottom.

Step 4: Attach Rear

Spread a the adhesive around the sides and bottom edges of the rear foam. Lay it between the sides and push it so it touches the bottom.

If you have big enough clamps use them to hold the cabinet tight until the glue dries otherwise use some wide painters tape to hold things in place.

Step 5: Attach Baffle To Inner Divider

Spread adhesive over one long edge of the Divider foam. Press it onto the back of the Inner Divider so that it lines up with the top and the side of the fan cutout as shown.

Use wide painters tape to hold it in place while the glue dries.

Step 6: Attach Divider to Chamber

Spread adhesive along the back of the Baffle and around the bottom and side edges of the Inner Divider. Carefully slide the Inner Divider and Baffle down into the cabinet so the bottom of the divider meets the bottom of the chamber and the back of the Baffle touches the Rear of the chamber as show.

Use wide painters tape to hold it in place while the glue dries.

Step 7: Attach Wood Strips

Apply adhesive to the sides of the wood strips that will come into contact with the foam or other wood strips and place them in the chamber.

Alternate putting the Front and the Top on to help line up the strips then use wide tape or clamps to hold them in place.

Step 8: Apply Weatherstripping

Let the Fuze-It dry and then carefully apply the weatherstripping to the wood and top of the Rear as shown.

Step 9: Make Holes in Top and Front

Now we need to make the recessed holes in the sides of the Top and Front for the dowels. This is a bit tricky because we're not making a hole all the way through like we did for the sides.

Start by laying the top in place and press down lightly so it presses against the weatherstrip. It's okay if it isn't flush with the sides as the weatherstripping will raise it up a bit.

Press and twist a length of 1/2" copper pipe through each hole on each side enough so that you make a clear mark of where the hole should be.

Remove the top. If you have a 1/2" drill bit you can try to drill 1" deep holes at each mark or drive the 1/2" copper pipe 1" into each mark. Use a bit of tape on the pipe to mark the depth. Carefully remove the inner plug of foam using a pic or small knife if you didn't drill. Insert a 1" length of pipe in each hole.

Repeat for the Front.

Step 10: Attach Fan and Thermostat and Wiring

Double check the instructions that come with the thermostat and power supply in case it's changed.

Start by stripping the adapter off the ends of the power supply and stripping some of the wiring. Obviously make sure it's not plugged in. Pull apart the two wires a couple of inches to give you more room to work with. Strip the ends of the fan wires as well.

Drill a small hole through one side of the chamber in front of the baffle (or in a different convenient location near the top of the divider) to feed the power supply wires through.

The power supply will have one wire marked with a white solid or dashed line. This should be the positive wire but it's good to check with a meter to be on the safe side. The wire that is all black should be the ground wire.

Make sure the power supply isn't plugged in before continuing.

Place the stripped end of the ground wire of the power supply and the Ground wire of the 12V fan into the terminal on the thermostat marked GND.

Place a small wire jumper between the K1 and +12V terminals. The positive wire of the power supply should also go into the +12V terminal.

The positive wire of the fan should go into the K0 terminal on the thermostat.

Secure the fan in it's cutout and use some double sided tape to secure the thermostat near the fan on the divider. Extend the thermostat probe into the main chamber.

How To Use Your Son Of A Fermentation Chamber

You should have 4 gallon jugs of water ready to go. If you can keep 4 in your freezer that's great. If not put 2 in the freezer and 2 in the fridge to keep them cold. You should have at least 2 gallons frozen before you're ready to ferment.

Remove the top and front of the chamber by pulling out the wooden dowels. Place 1 frozen gallon into each of the cavities in the rear of the SOAFC. Place your fermentation vessel into the main chamber. It's best if you can cool it down to fermentation temperature (or close to it) before placing it in the chamber.

Set the thermostat to your desired temperature. Remember the thermostat is in Celsius not Farenheight so do the appropriate conversions if necessary.

Plug the power supply in and make sure the fan is blowing if the room temperature is warmer than your fermentation temperature. If everything is working fine replace the top and front and secure them with the wooden dowels.

When the thermostat senses the air is too warm in the chamber it will start the fan. The fan will circulate the air in the chamber through the back cavities that contain the frozen jugs which will cool the air. Check on the temperature once every day or two and replace the jugs if they are no longer frozen.


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