Fermentation Chamber

[GPSaxophone]

Or as my kids call it, my "Beer Dungeon"

I've been looking at several threads on fermentation chambers and using SketchUp to model it. Thanks for the great ideas, I've incorporated several of them into my own design and look forward to building it soon.

Requirements:
- This will go in my garage next to an existing workbench. The height of this chamber should match the workbench. The chamber should be solid enough to hold two 20" toolboxes (up to 100 lbs each). I always run out of workbench space and don't have a rolling cart for the toolboxes, so I'll use the top surface of the chamber for the toolboxes to save workbench space.
- I have a maximum width of 42" to work with next to the workbench. The chamber must fit there.
- I want enough room inside the chamber to hold 2 fermenting buckets. Any "leftover" space can be used for freshly bottled beer so it's also temperature controlled.
- The garage ranges from 80s in the summer to 50° in the winter (worst case).

Supplies:
- I was able to secure a mini fridge at Goodwill for $40. I tried looking on CL but most working units in this area were $100 and up.
- I also have an STC-1000 for temperature control.

Because of the height restriction, I opted to not use casters in the design. Instead, I have a solid plywood base. I don't expect to move it, but if it becomes necessary I have a handtruck available. Instead of 35" legs, I had to account for 9/16" plywood on the bottom to match the workbench height. The workbench is 24" deep, so that's what this will be. The center post makes the left side opening match the interior dimensions of the minifridge. I also had to offset the framing from the edges of the plywood by 1/8" to account for the side panels or skins. This was a bit of work learning how to do it in SketchUp, but I managed.

The skins don't cover the end where the minifridge goes, so the framing is flush on this end. The coils on the fridge are on the back, so they'll be exposed on the workbench side of the chamber. The top crossbraces are horizontal to allow the fridge to fit. I can remove the feet of the fridge if necessary, but I was thinking of drilling 1" holes in the plywood base to set them in. This way the fridge wouldn't be able to slide around at all.

Since I'm using 2x4s (which are actually 1 1/2 x 3 1/2) there is room for 1 1/2" foam in the side panels and on the end (left open in this image on purpose). The fridge door will be used instead of making a custom one.

There is about an inch between each side of the fridge and the framing for more foam insulation. Those gaps may be useful if I have to get another mini fridge and it isn't the same size - I don't want to rebuild the entire cabinet. I'll also build the floor up to match the inside bottom of the fridge and finish the inside with melamine. Using sketchup, I should have enough room for 2-3 buckets or 2 buckets and several bottles. I may use the shelves in the fridge for bottles so I can fit more in.

Looking at the completed design, I may end up taking some space away from the inside so the door is flush with the front edge of the workbench and cabinet. I can't start building it for at least another week, so that gives me time to think about it. Now that I have some experience with Sketchup, it shouldn't be too hard to try out some variations.

 

[GPSaxophone]

Build day is here!

Measure twice, cut once. Still, after cutting I just had to see how well the minifridge fit on the base:

I built the back wall first:

Then enclosed the rest:

There's enough space for everything:

Now that I know it all fits, I cut out space for the door:

You can see the framing for the door seal inside. I bought some steel strips that will attach to it so the magnetic door seals. I didn't quite have enough time today to install the door, but I did make sure it fits and it will be flush with the plywood on the front. The top is just set in place for now, I'll screw it down tomorrow. Not pictured are the cross braces over the fridge. I had to trim some 2x4s a bit so they would fit between the top of the fridge and the top of the chamber.

Home Depot didn't have the foam board I wanted, so I'll try another store tomorrow or go to Lowe's. Still, got a lot done and should be ready soon.

 

[kurds_2408]

Man that's incredible. I got a spare mini fridge I've been thinking of putting a collar on to make a single ferm but I think your idea would be much better. Let me know how it all goes cause I'm def gonna copy this.

 

[GPSaxophone]

Gluing the metal strips around the door frame so the magnetic seal will have something to grip to:

Door frame back in place:

1" foam insulation on the inside. There is a 1/2" air gap between this insulation and the outer layer. Each layer is rated R-3.

Test fit with the fridge:

All wired up. The temperature probe is taped to the insulation and hangs down from the back of the chamber. I'll finish out the inside with 1/4" melanine. One reason is for easy cleaning and the other is so buckets and carboys aren't placed directly on the insulation.

Completed chamber starting to cool:

The new workbench area:

I didn't pay attention when I bought my STC-1000 so it displays in Celsius. I don't think that's a big deal though since I'm not going to change it that often. I can always print out a conversion chart for quick reference.

The hardest part of the build was recessing the door so it's flush with the front of the chamber. I ended up completely redoing the frame for the door to make it fit the front cutout. There's only about 1/4" clearance around all sides of the door, which is enough, but barely. I like the end result, so the extra work was worth it.

The chamber is very solid, so I'm not worried about the weight of the toolboxes on the top. I thought about using the surface for brewing stuff (which is far lighter) but really, I need the space for the toolboxes. That was one of my design goals in the first place, so it all works out. I have room elsewhere in the garage for brewing supplies anyway.

 

[BigFloppy]

great build. looks outstanding

 

[Sudz_Makenzie]

Great project! You obviously have skills

 

[rekoob]

Very nice build.

 

[Wilde]

Looks great, very clean.

 

[astronomical]

could reflash STC if its the right board. see https://www.homebrewtalk.com/f51/stc-1000-a-464348/

The features list is robust. I was pretty impressed.

 

[cubalz]

Very nice indeed. Does it hold temperature well? I thought about doing this type of set up but I was worried about overworking the 'fridge due to the extra space it needs to cool.

 

[GPSaxophone]

The temperature has been holding very well. I have a case of full bottles and a few other items in the chamber now, so it isn't just empty. The fridge powers on when the temp reaches 20.5°C and turns off again when it hits 20.0°C. This takes about 5 minutes. I haven't timed how long it takes between cycles, but really haven't noticed it coming on much at all. I still need to add a heater inside before winter is here, but thankfully George RR Martin writes slow enough that I can brew another batch before then.

I'm brewing this weekend, so this will be the real test.

 

[Michael357]

Beautiful craftmanship GPSaxophone. I bought the materials to build one myself today. Based on your design and several others. In one thread, someone mentioned not to enclose the fridge because the sides get very hot. Are you having any heat issues with yours being enclosed? I like the fact that it's enclosed, but worry about the fridge getting too hot and possibly causing damage and shortening the life of the compressor.

 

[riderkb]

Very nice work. Make sure that there is good air flow behind that fridge and it should work fine.
What about condensation? Most dorm fridges have a drip pan that doesn't hold very much. If you use a set point of 16C in the summer (that is where I leave mine) then the compressor will be running a lot and making a lot of condensation.

 

[GPSaxophone]

My fridge doesn't have coils in the sides, they're all on the back. As a result, the fridge sides don't get warm. The back of the fridge (on the side of the chamber) is open to my workbench, so it gets plenty of air for the heat exchange.

I have checked the drip pan inside several times, but haven't found any condensation in it. One reason is that the fridge doesn't come on very much, partly because of the insulation, and the other is that Colorado is a very dry (arid) state. It helps us out in the winter by drying out the roads after it snows, but has its downsides as well. Wood instruments (like guitars) dry out and crack much faster here than in other places.

I took advantage of Labor Day to brew a Blue Moon clone that I found on the forums here. It smelled real good while brewing, especially after adding the orange peels and coriander. Here's a shot of it in the chamber:

I'll be brewing a pumpkin ale in another week or two.

 

[Michael357]

My fridge doesn't have coils in the sides, they're all on the back. As a result, the fridge sides don't get warm. The back of the fridge (on the side of the chamber) is open to my workbench, so it gets plenty of air for the heat exchange.

Ok, thanks. Good to know. It appears that the entire fridge is enclosed. My fridge is made the same way, all coils in the back.

 

[Carlscan26]

Just a word of warning - just because you have could on the back of the fridge doesn't mean that they're all on the back. Mine has them on the back and also some on one side.

You can test it by turning it in and then feeling the sides and top for heat when it's running. And/Or, you should also be able to see the lines as they run out and into the compressor and see any branches, etc. That lead under the sides of the fridge.


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[Michael357]

Just checked my fridge. Coils are on the sides too. So to ensure the sides get enough airflow, I'm going to borrow this vent idea as seen in the pic. No, this is not mine. I wish though, lol. Do you think if i install vents on the sides and the back, it'll get enough airflow? Thoughts and ideas would be appreciated.

 

[GPSaxophone]

Vents like that are probably going to be OK. A lot of refrigerators are pushed up against a wall even though there is supposed to be 4-6" clearance. This would go for the sides as well if that's where the coils are. If you build a solid cabinet for your mini fridge to sit in you may need venting (like you pictured) or even a fan to allow for adequate heat exchange without shortening the life of your fridge. I was lucky that I found a model that only has the coils in the back so this isn't an issue for mine.

 

[Carlscan26]

It's not just the life of the fridge - its capacity to cool can be affected too.

I think the vents are a good idea. Try to set them up so you have convective airflow


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