Looking for advice on building a collar for my mini fridge fermentation chamber

Hello All,

I recently bought a 3.6 cu ft mini fridge off CL for a fermentation chamber. And all though there is a lot of info here about building fermentation chambers, I live in a small studio apartment and need to keep the footprint of this thing to a minimum.

I'm looking for some advice (pics would be great too) on how to, as simply as possible, build an extension collar to give me an additional 6" of depth and be able to insulate it properly. The outer black shell is 3/4" thick, and it is a combined 1 1/8" thick with the inner white part of the fridge. I also plan to use the original door after reinstalling the door seal.

Thanks in advance for all the help!

For 6" you'll need a 2X8 and I'd be concerned about it peeling off without a support.

I used 2X4s as I only needed that much depth. But due to the weight of the glass door on my wine fridge I was converting I mounted a piece of plywood to the base to support the collar. I used a construction adhesive to glue the collar to the opening.

I didn't insulate the collar - I see no reason to as it never feels cold to the touch and the fridge barely cycles once its to temp. Keep it simple.

I used magnetic tape to help the door seal shut - it would have been perfect except the 2X4 I used was not planed evenly enough. So I'd suggest you get finish grade lumber or plane it down yourself. I got lucky though because my fridge has a reversible door and I was able to use the empty holes to put a pin through to lock the door shut - this pulled it tight enough to seal fully.

Finally, I added casters on the bottom to move it around and I mounted the temp controller to the side of the collar so it's all together. I just role it around the garage to wherever is convenient and plug it in.

Hope that helps. I'll try to post pics tonight.

Here are some shots from when I built it. I pulled the original thermostat out and ran the power line for the heat wrap through that opening, caulking it all up, etc. - that was nerve racking bending the cooling plate but it all went fine. I also took the light out and ran my thermocouple in through there. I keep meaning to weather seal the wood at least on the inside surfaces but so far I've been careful and not had any spills. (The top is on backwards in the first pic)

That's a great build.

LabRatBrewer said:

That's a great build.

Click to expand...

Thanks!

It was made with scrap wood I had laying around. As mentioned earlier I would use better lumber for the collar were I to do this again.

Likewise, the metal straps at the top were what I had laying around and were easy to use as they were predrilled. They don't line up perfectly but with the top on they barely stick out. Those were probably not needed but I had them and they provide some extra support for the collar. I used another bracket from a towel rack and two screws for the lip on the cover to catch onto - it has screws on the back but on the front it originally latched over the metal bracket that the door attaches to. Hope that makes sense.

I will be replacing those 1" casters with bigger ones - again it's what I had on hand but they suck and so will be replaced.

But even given what I used, I'm really happy with it.

And a picture of it completed (ignore the block of wood and left over wire sitting on top):

I really like the gass door of the wine fridge. That would save a ton of energy lost to my opening the door to peek.

LabRatBrewer said:

I really like the gass door of the wine fridge. That would save a ton of energy lost to my opening the door to peek.

Click to expand...

Yeah but you have to cover it up to block light from skunking the beer. I'm currently using several layers of black trash bags and have been planning on insulating the door to simplify that. I hear you though as it does make peaking easy.

Hedo-Rick have we totally derailed this thread or is this what you were looking for?

Carlscan26 said:

Hedo-Rick have we totally derailed this thread or is this what you were looking for?

Click to expand...

Sorry If derailed....re: skunking: a curtain would work.

LabRatBrewer said:

Sorry If derailed....re: skunking: a curtain would work.

Click to expand...

Wasn't calling you out, just realized the OP hadn't commented back. Glad my info is helping you at least

Carlscan26 said:

Wasn't calling you out, just realized the OP hadn't commented back. Glad my info is helping you at least

Click to expand...

No worries...I've just been thinking of declaring my fridge at work dead, replacing and the converting it like you did. My partner is sympathetic to my brewing obsession.

I was at work and just getting home now. That's why I didn't jump in on the conversation. Gotta love the restaurant business.

Anyway, totally dig the build. It really gives me a jumping off point. Gotta be honest though, working isn't really my thing, so I'm just gonna keep it really simple and get this thing done so I can get to making some Kolsch.

I'll throw some pics up once I get it started.

Thanks again!

Hedo-Rick said:

I was at work and just getting home now. That's why I didn't jump in on the conversation. Gotta love the restaurant business.

Anyway, totally dig the build. It really gives me a jumping off point. Gotta be honest though, working isn't really my thing, so I'm just gonna keep it really simple and get this thing done so I can get to making some Kolsch.

I'll throw some pics up once I get it started.

Thanks again!

Click to expand...

Great - glad to help. The collar and base, etc. only took a few hours - its pretty simple really.

Redoing all the wiring and assembling the dual stage temp controller etc took a bit longer. But you can buy one premade and just plug the fridge and heat pad in. Or if you're not worried about heat just use a single stage controller. If you're not going to use it for lagering you can just crank the internal thermostat to as cold as it will go and don't worry about rewiring it even (you will still need the controller just no need to mess with the wiring in the fridge as the controller will turn off power well before you would et as low as the internal thermostat is set to). Hope that makes sense.

Carlscan26 said:

Great - glad to help. The collar and base, etc. only took a few hours - its pretty simple really.

Redoing all the wiring and assembling the dual stage temp controller etc took a bit longer. But you can buy one premade and just plug the fridge and heat pad in. Or if you're not worried about heat just use a single stage controller. If you're not going to use it for lagering you can just crank the internal thermostat to as cold as it will go and don't worry about rewiring it even (you will still need the controller just no need to mess with the wiring in the fridge as the controller will turn off power well before you would et as low as the internal thermostat is set to). Hope that makes sense.

Click to expand...

I'm feeling pretty confident about the collar build after looking at your pics and re-reading your thoughts.

I'm still trying to work my way through the temperature controller part of this. I don't plan on using heat because the ambient temperature in my apartment is pretty much always around 70F. However, I do plan on using my chamber to lager, so I need to get myself educated on getting the wiring done. Also, I'd like to wire a small computer fan in to aid in cooling. Would you recommend a Rancho controller or the ebay aquarium temperature controllers that seem to be so popular here?

The eBay one and the other sources for it are hard to beat price wise...

Wiring in a fan is easy - just route the line out the condensate hole above the compressor add a plug and plug it in to a constant power source.

do people do this for kegerators? I would assume a little more insulation would be needed because of the mostly cooler temperatures but this might be an easy way to have 2-3 kegs in one dorm fridge I can find so cheaply in my town.

Hedo-Rick said:

Gotta be honest though, working isn't really my thing...

Click to expand...

Tinga said:

do people do this for kegerators? I would assume a little more insulation would be needed because of the mostly cooler temperatures but this might be an easy way to have 2-3 kegs in one dorm fridge I can find so cheaply in my town.

Click to expand...

Yes they do. You can find a lot of threads about that though usually it's for chest freezers. No reason you couldn't do it for a dorm fridge if its tall enough.

A lot of people insulate their collars. I did on my keezer too but I doubt it makes that big a difference. It was easy to fit on though so I added it just for that extra bit. Lots of people don't bother too.

I lost a lot of cool air with the temp probe going under the door seal - it never seals fully hence why I went to the trouble to run it through the light mount.

With insulating you only get a few Rs improvement and for how it would fit for the ferm chamber I figured it would get in the way/damaged/be too much work to sandwich between thinner pieces of wood etc. I was trying to keep it simple and use materials I had on hand. I'm satisfied with just the 2X4.

Just a quick update.

Manged to get the collar attached to the fridge over my weekend. Ended up using finished grade 2x4 for a nice smooth fit.

Now I need to get the door hung, get a temp controller and pc fan wired in and it will be time to brew some Kolsch.

Thanks again for all the help!

Nice work!

Got the door re-mounted today and my temperature controller should be here tomorrow.

Used 26 gauge, galvanized steel around the front of the collar for the door seal to seat to.

I should be brewing up a batch of Kolsch next Tuesday!

Thanks again for all the help!

That's nice. Did you buy those premade?

Had a local metal shop them for me. Cost me $4.00.

Hedo-Rick said:

Had a local metal shop them for me. Cost me $4.00.

Click to expand...

Cool thx

Carlscan26,

I was wondering, do you route your temperature probe through the condensate hole above the compressor, or did you make a new hole in the cabinet somewhere and seal it up?

Also, you wouldn't happen to have a pic from the side that shows your temp controller setup?

Hedo-Rick said:

Carlscan26,

I was wondering, do you route your temperature probe through the condensate hole above the compressor, or did you make a new hole in the cabinet somewhere and seal it up?

Also, you wouldn't happen to have a pic from the side that shows your temp controller setup?

Click to expand...

I ran mine in through the top where the light was (I removed it). I would advise either a hole in the collar or through the condensate drain though be careful to arrange it such that any condensate ends up on the pan and doesn't follow the cable elsewhere.

I'd probably go through the collar if I did it again just for simplicity and more lead length.

I'll snap and post a picture this evening.

Here's a picture of how I mounted it. This controller does not have much room for wiring and I originally wired this up with a receptacle attached but then decided I wanted to hard wire it, so I pulled the plug out.

You can see my patch for amending my mistake of rushing and not drilling a pilot hole for the hinge mount. I filled the crack with epoxy to hold the screw (which was still tight but just in case) and I added that metal bracket to prevent the split from getting worse.



You can also see where I ran the wires up under the top of the fridge - the cover was already damaged there so I just widened the opening with a file and ran the wires through there. The grey wire is the sensor, and the two black ones are for the fridge compressor and the heat wrap.

The compressor is hard wired. The heat feed ends in an outdoor plug inside the fridge (I ran it in through the hole where the original thermostat came through behind the cold plate). This gives me some flexibility for removing or replacing the heat wrap, etc.

Hope this helps.

Thanks for the pic. I pretty much decided to mount my controller in the same place. Now I need to come up with a plan to route the temp probe and fan power cord. But I think that is going to be just just as easy as drilling a 1/4" hole in the collar, running them through and sealing it up with a bit of caulk.

Wired and tested the controller last night. Everything works good. However, the fridge did seem to struggle to get below 40F. Not that I plan on being at temps that low very often, but I think the added computer fan will help the fridge get there and maintain lower temps when I do do some lagering.

That sounds like a good plan. I may reroute mine that way too if I ever get around to it lol.

Just wanted to share a couple pics of the finished product. It's awesome! It holds temp so well! It cycles on every 4-5 hours for 10-15 minutes. Pictured is the Kolsch I made on Monday. I routed the the temp probe and power for the 120mm computer fan through a small hole behind the door hinge.

The only other thing I wish I could have done different, would have been to have a receptacle instead of the split extension cord and splitter to power the chamber and fan. It's done well, functional and safe, but would have liked the clean look of the receptacle. Hopefully I can get that accomplished on the next project. I have another fridge and plan on building a chamber to house two carboys for more moderate temps and keeping the smaller chamber for cider and lager temp needs.

Thanks again for all the help!

Nicely done!


You can still wire a box on if you really want it. :cheers:

what did you use to attach the collar?

On mine I have it screwed into the plywood extension/base I have under the fridge, then glued to the fridge opening and finally some metal brackets at the top from the original hinges to the top of the collar. Probably all overkill but hey it's not going anywhere.

Now if only I had used a 2X6 I could fit one of those cavern SS carboys. I'm an inch short right now - doh!!! But it fits my current carboys just fine.

I used liquid nails to adhere the 2x4's to the mini fridge. However, be sure to build some sort of brace under the bottom 2x4 or what ever dimension lumber you are using. Mine cracked loose one day sliding a full carboy out. Luckily, the bottom 2x4 of my collar sat exactly 1.5" off the ground, so I just glued a piece of scrap 2x4 under that, made sure all the caulking inside was sealed up and have not had a problem since.