Under work bench fermentation chamber

Hi guys, I built this a week or two ago. I plan on using it for ale fermentation only, as I've got a chest freezer for lager brewing and conditioning. So far I haven't gotten around to actually fermenting in it, but it will hold at 60F empty in the Nashville weather. It's big enough for at least 4 carboys, maybe 5 if I stagger them carefully enough.

I moved into a house not too long ago, and needed a workbench/work area. I got inspiration from some of the threads here to make the space underneath a fermentation area. The hardest part was probably finding a mini fridge tall enough to hold a carboy with airlock. Mini fridges without freezers are just about impossible to come by, it turns out, and a freezer usually takes up just a bit too much room.

Its a 2x4 frame with 3/4in plywood. Between 2x4 studs I placed 1x4 spacers to create a 3/4in air space, and the stuck a layer of 3/4in foil-faced insulation on. I had enough room after doing that to put another layer of 3/4in foil-faced insulation on. Then I foil taped all the seams. The floor got a layer of whiteboard for easy carboy sliding, and all the outside joints got caulked. The top of the workbench is the old laminate kitchen countertop that I ripped out when I redid the kitchen.

So the chamber, outside in, is plywood, 2x4 frame, 1x4 spacers, 3/4inch air space, 3/4in foil-faced insulation, another 3/4in foil-faced insulation, and whiteboard on the bottom.

Very nice!

How often is the fridge running to maintain 60F?

It seemed to run fairly often. I'm hoping that when I actually get a couple carboys in, not only will I seldom want to ferment that cold, but having some thermal mass in there will help out cycle times. If it still kicks on too much for my comfort, I guess I'll go around with more caulk to start.

Rundownhouse said:

It seemed to run fairly often. I'm hoping that when I actually get a couple carboys in, not only will I seldom want to ferment that cold, but having some thermal mass in there will help out cycle times. If it still kicks on too much for my comfort, I guess I'll go around with more caulk to start.

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As my home inspector told me, caulk is cheap! I would just caulk the hell out of it now.

You could also put the temp prob into a bottle of water so that has to heat up or cool down, i do it in my kezzer and it works well

It looks like you're pretty well sealed, not sure that caulk will help much. If you want to reduce the amount the refrigerator runs you could try thicker insulation, or reduce the area of the cooled space.

Maybe cut a removable insulation 'wall' that you can use to block off part of the cold space when you're only fermenting 1 or 2 beers.

With a smaller cooled space you might be able to do lagering as well!

Dohboy said:

You could also put the temp prob into a bottle of water so that has to heat up or cool down, i do it in my kezzer and it works well

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that just accomplishes the same thing as widening the hysteresis band of the temperature controller. it will reduce the number of times the compressor cycles on and off, but increase temperature fluctuation. better insulation will also reduce the number of times the compressor cycles, but also save energy and keep a tighter temperature band.

FRS said:

Maybe cut a removable insulation 'wall' that you can use to block off part of the cold space when you're only fermenting 1 or 2 beers

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Now THAT is a great idea. Simple and should be effective. Thanks a ton.

That's the best use of space when you have a small garage ...

You've got a bit of that pink slime mold on your drip tray...

That looks like a nicely finished garage, though, congrats.

FRS said:

Maybe cut a removable insulation 'wall' that you can use to block off part of the cold space when you're only fermenting 1 or 2 beers.

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This morning I cut up some insulation to make a dividing wall for when I'm only fermenting 10g. I put it in and set the fridge to 68ish. It went from over 80 down to set temp in maybe 15-20 minutes, and is holding there easily, without the compressor kicking on much at all. Awesome suggestion and its working like gangbusters.

The wall is just to the left (the fridge side) of the door. I'm thinking about scooting it over to just past the door and seeing if it struggles. That'd let me know I've got a big insulation problem around the door.