Making a fermentation chamber/fridge

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Making a fermentation chamber/fridge

Post by Manngold » Thu May 04, 2017 11:16 am

Hi all,

I have a spare fridge that is surpass to requirements that I want to convert into a fermentation chamber, but I am having a bit of trouble figuring out what parts I actually need to invest in to make it viable. I have checked that it fits a FV comfortably (raised from the floor).

From my understanding I need the following:

A shelf made of good wood for it to sit on with holes drilled through the bottom to allow circulation of hot air.
A 40W tube heater (or equivalent) - if anyone has a suggestion of what to buy that would be useful.
An Inkbird ICT-308S to control the temperature in the fridge.
A couple of PC fans to help circulate the air - do I need this?

In terms of putting it all together I would like some advice on the best possible ways. My understanding of it as follows:

Cut the shelf to size. Drill holes.
PLace the tube heater in the bottom.
Drill holes two holes in the side of fridge. One for the tube heater, one for the probe on the Inkbird.
Plug the tube heater into the inkbird.
Plug the fridge into the the inkbird (I guess that I need to put the fridge socket into the bit that says cool on the inkbird).

What I cant get my head round is what to do with computer fans. What do I wire them to?

One other thing, the fridge I am using is an old kegerator I made. Any advice on what I could use to seal the door where I made holes?

Also if anyone can point me in the direction of good guides/how to videos I would be really grateful.

Many thanks


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Re: Making a fermentation chamber/fridge

Post by Jocky » Thu May 04, 2017 11:52 am

I didn't cut anything for my fridge. I just ran the cables through the door seal. Still works fine.

I have a fan in mine to help circulate hot and cold air (avoids big temperature swings and potential pendulum between too hot and too cold). It's 5v and powered from a USB plug.
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Re: Making a fermentation chamber/fridge

Post by Manngold » Thu May 04, 2017 1:12 pm

Brilliant, thanks Jocky. Am I correct in where I think the plug sockets should go into for the fridge and tube heater?



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Re: Making a fermentation chamber/fridge

Post by k1100t » Thu May 04, 2017 1:13 pm

Jocky wrote:I didn't cut anything for my fridge. I just ran the cables through the door seal. Still works fine.
Same here.
The tube heater sits in one of the door shelves. Ive got one like this from Toolstation -> Tubular Heater 60W 55 x 305mm
I haven't got round to putting a fan it mine yet though...

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Re: Making a fermentation chamber/fridge

Post by PoppaZombie » Thu May 04, 2017 1:51 pm

Thought I'd chip in with a couple of things I picked up when I made mine. When you buy the tube heater it will most likely come without a plug attached. I think this is because they are generally hard wired into switches in normal applications so its how they come in the box. Before you put the plug on, run the cable through the condensation drain at the back of the fridge. It avoids any drilling into doors/walls or messing with the door seals. I have my STC-1000 sensor running through the drain too as there should be just enough space. Not too sure what size the inkbird sensor cable is but hopefully it'll fit alongside. I have it set that way in both my temp controlled fridges.
Also, the tubes come with some holding brackets too btw. Screw them onto a bit of board which will act as a stand on the fridge floor.
I bought mine off ebay and they were 60W.
When making the shelf for the beer to sit on, I wouldn't worry about drilling too many holes and I wouldn't drill any directly under the fermenter itself. The area and wooden shelf directly above the heater can get pretty hot and I wouldn't want the yeast cake inside at the bottom of the fermenter to get that warm. As long as there is some room for the heat to get past the shelf, up between the shelf and the door for example, it'll be ok without the holes.
I haven't bothered with any pc fans in mine. One is only a undercounter size anyway. In the larder fridge I have my sensor around the mid height of my fermenter. This averages out any stratification of air temps good enough for me. After using it for a few brews and checking beer temps, it seems to be spot on.

To seal an old tap hole in my brewfridge, I used silver tape on one side, stuffed the void with some cotton wool and then taped up the other side. Worked for me. ... 1623775680

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Re: Making a fermentation chamber/fridge

Post by Manngold » Fri May 05, 2017 7:41 am

Brilliant, thanks all.

Am I correct in my assumptions about where the plugs go? Do both the fridge and heater work at the same time then to create the desired temp? Sorry, a complete and utter novice.

PappaZombie, thanks for the tips on the tape! Have ordered some.


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Re: Making a fermentation chamber/fridge

Post by Fil » Sat May 06, 2017 4:49 pm

yes your right about the plugs :)

they wont run at the same time it will apply heat or cold as and when required,

Fans are crucial to avoid the system chassing itself (running hot and cold altenatively never stopping) if you set a small temp difference to trigger inputs ie heat or cool when it slips 1c off target..

your exchanging heat and cold from the fridges respective radiators via the air in the fridge, to maximise efficiency that air needs to be kept in motion. buy a commercial or top end domestic fridge and it will have fans fitted, for the sake of a £ or 5 minutes pulling one from an old pc case and a redundant dc phone charger its a mistake not to add one imho..

also be mindful you can replace the thick flex fitted on a tube heater with thinner lighting flex that will thread through the back drain hole much easier, although its a heater its running with light bulb level power consumption ;) 40w..
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Re: Making a fermentation chamber/fridge

Post by kisslikeether » Sun May 07, 2017 2:01 pm

A few further thoughts if its helpful.

+1 on on the use of fans - it makes a big difference. I've made three of these from old fridges now, two for dispensing and one as a fermentation chamber. While the DC fans can be really cheap you may want to consider AC ones from Maplins as they can be wired into the same circuits as the heater and fridge without a power adapter. I''ve got two in the fermentation fridge - one just above the bar heater and the other where it can distribute the cold air whenever the fridge is triggered.

As for the shelf I didn't bother with a solid sheet of wood - i just made a square frame with two central cross beams wide enough to support the fermerter. That allows a lot of space for the air to circulate around it. My fridge is full height and will (just) take two fermenters at the same time - so another advantage of the square frame for the top shelf is that if you set the cross beams off center there's room for the airlock of the bottom fermenter to poke up between them.

Finally, for my first fridge a did ram all the cables through the drain hole at the back, but for the others I found it much easier to drill the side to create a hole big enough. If you go for two AC fans there's a cable for each, plus the heater cable and the temperature probe. You can get away with a single cable for both the heater and the associated fan if you use a junction box in the fridge, and the cables for dc fans will be smaller, but however you do it there's still a lot clogging up the drainage hole (and its there for a reason). A WORD OF WARNING THOUGH - obviously drilling presents a risk, and if you hit the coolent lines the fridge will be knackered. If in doubt there's plenty of posts on the forum showing how to determine where the lines are in your fridge (mine have all been on the back wall) and if you're still unsure but want to drill anyway there's always the option to put a hole in the door nearest the hinges.

Good luck...

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Re: Making a fermentation chamber/fridge

Post by Matt in Birdham » Wed May 17, 2017 3:41 pm

All good advice, I have pretty much done the same. For an old fridge, drilling is probably neater (if you dare), but since I ended up buying a new one to replace a duff one I haven't drilled anywhere in the new one yet (until warranty period lapses, at least).
I went with a 5mm sheet of alu for the shelf (surprisingly cheap online) for a slightly slicker look - holes drilled and fan mounted under. The alu slots in to where the bottom shelf was, and is supported by a few bits of alu box section at the front. My cables are through the drain (heater & 240v AC fan) with probe cables under door seals.


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Re: Making a fermentation chamber/fridge

Post by Hudson1984 » Wed Oct 21, 2020 8:30 am

if it's just to store cans of beer pretty much anything will do. I've a Guiness bear fridge, which sits in my office. Does the job it's meant to.

Fridge is a fridge in all reality. as long as it cools - my brew fridge was a tenner off gumtree - still does the job it's meant to albeit less efficiently than something newer

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Re: Making a fermentation chamber/fridge

Post by Pigster » Wed Nov 18, 2020 12:10 pm

Hi all,
Really interested in this topic as temperature controlled fermentation sounds like a great way to go next on my journey.
As luck would have it I’ve found a fridge freezer up for grabs locally. Fridge is 45x 65 which is a good size, freezer 40x40 which I suspect is too small.
Am I better putting a heater into the freezer compartment and leaving the fridge as is, or something different?
Many thanks!

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Re: Making a fermentation chamber/fridge

Post by Meatymc » Wed Nov 18, 2020 1:19 pm

Pigster wrote:
Wed Nov 18, 2020 12:10 pm
Really interested in this topic as temperature controlled fermentation sounds like a great way to go next on my journey.
Hi Pigster

See you're quickly getting into everything!

You want to be able to control the fermentation temp so you're heating and cooling the same space - the fridge only.

I haven't tried converting a fridge/freezer just yet although I have one in the garage I use for chilling water for post boiling cooling and the freezer to store my home grown hops. My stand alone fermentation fridge is in the utility - converting that was simple based on instructions off here.

Others will hopefully comment on how to add heating just to the fridge whilst retaining an operating freezer - sure the principle is the same but I'm not sure the wiring is.

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Re: Making a fermentation chamber/fridge

Post by Cobnut » Wed Nov 18, 2020 1:42 pm

The usual way to get this working is to use STC-1000 or Inkbird which switches the fridge on for cooling (heater off) and the heater on (Fridge off) for heating. Without significant rewiring of a fridge-freezer, I don't see this as achievable.

Better to find yourself a 2nd hand larder fridge. Mine was £50, so not a large investment.
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Re: Making a fermentation chamber/fridge

Post by Evvo » Tue Dec 08, 2020 10:02 pm

Regarding drilling I found the safest way to get the heater cable into the fridge was to put a hole in through the compressor cover in the bottom of the fridge. Going in from the back with an old soldering iron. I never found any cooling coils in that area and even if there had been they would not have been damaged by the soldering iron. I hope that is clear as it was harder to describe than it is to actually do it.

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Re: Making a fermentation chamber/fridge

Post by Storm Brewing » Mon Jul 12, 2021 3:19 pm

I am new to the forum so please excuse any misunderstandings I may have! #-o
I am currently planning to build a fermentation fridge but could do with some experienced advice! I have read this thread with interest and all seems to make sense. I have managed to obtain a used under counter fridge and I have checked its effectiveness by placing a fv with 5 gallons of water inside, turning the fridge to max and recording the temperature. Thus far the temperature has dropped to 8 degrees C . This is obviouly ok for fermentation purposes but I was hoping to incorporate a 'cold crash' (2 - 4 degrees C) into my process as i understand this is beneficial, especially with Pilsners ??

Do I need to get a better fridge, adapt it to by- pass the inbuit thermostat or forget about cold crashing?

Any advice will be gratefully received! :D

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