# Hacking the thermostat on a fridge so it chills to zero



## Muz (10/8/19)

I'm still trying to work out my fermentation temperature control.

I had decided to bite the bullet and buy another freezer for fermentation temp control. I've been looking for a second hand upright freezer on gumtree as I like the idea of just opening the door and doing gravity transfers, bottle straight from the fermenter etc. and this isn't possible with a chest freezer. Problem is all the upright freezers I'm seeing have chill coils in the shelves so they can't be removed to fit my brew bucket.

Are there upright freezers out there where the shelves can be removed?

If not is it possible to hack an upright fridge thermostat so that it chills down to cold crashing temps (I usually crash around zero)? Any advice on how to do this?

Thanks!


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## akx (10/8/19)

There are upright freezers where the shelves can be removed. I picked one up of gumtree for my fermentation fridge. Its great. I never bothered with rewiring the thermostat, and picked up an inkbird controller. Let's me use it through winter with a heater to keep at 18. Good luck!


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## beer gut (10/8/19)

My fridge cools down to -1° or so I haven’t tried going cooler in case my fermenters freeze.

It’s a Fisher & Paykel fridge only no freezer around 500l. Scored it off gumtree for $150


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## theredone (12/8/19)

beer gut said:


> My fridge cools down to -1° or so I haven’t tried going cooler in case my fermenters freeze.
> 
> It’s a Fisher & Paykel fridge only no freezer around 500l. Scored it off gumtree for $150


Sounds like urs is similar to my f and p 400ish fridge. Have u found that it’s takes a while to get from 18 down to 2 or so for cold crash? I suspect there might be some internal override that is not letting compressor run for extended periods of time?


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## djebel (12/8/19)

On most fridges you can bypass the internal thermostat entirely, making the fridge run constantly. Just a matter of unplugging wires, and joining them up correctly.
*
Don't attempt this if you don't know what you are doing.* Get a proper fridgey out to do the job.

Then you just get hold of an external temperature controller, and Bob's your auntie.


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## beer gut (12/8/19)

theredone said:


> Sounds like urs is similar to my f and p 400ish fridge. Have u found that it’s takes a while to get from 18 down to 2 or so for cold crash? I suspect there might be some internal override that is not letting compressor run for extended periods of time?



The fridge pretty much gets it down in a day and a half this shows it go from about 18° - 0.6° in around 30 hours


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## Drewgong (12/8/19)

Heres mine i got on Facebook marketplace for $100 all freezer works terrific off inkbird wifi controller


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## Madscientist86 (12/8/19)

I modified my series 3 kegerator as it was about 4 degrees out, wonder if similar can be done to a standard fridge probe?


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## TheBeerBaron (13/8/19)

Drewgong said:


> View attachment 116292
> View attachment 116293
> Heres mine i got on Facebook marketplace for $100 all freezer works terrific off inkbird wifi controller



Geez that is a mean deal! I need one this size to fit the FermZilla in


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## sp0rk (13/8/19)

TheBeerBaron said:


> Geez that is a mean deal! I need one this size to fit the FermZilla in


Mine is bigger and was $20...


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## Grmblz (14/8/19)

Muz said:


> I'm still trying to work out my fermentation temperature control.
> 
> I had decided to bite the bullet and buy another freezer for fermentation temp control. I've been looking for a second hand upright freezer on gumtree as I like the idea of just opening the door and doing gravity transfers, bottle straight from the fermenter etc. and this isn't possible with a chest freezer. Problem is all the upright freezers I'm seeing have chill coils in the shelves so they can't be removed to fit my brew bucket.
> 
> ...


Be careful of frost free freezers, they periodically over ride the thermostat and heat up to melt the ice which makes them a pain to modify, the older ones usualy are not frost free but have the cooling elements in the shelves and cost a fortune to run. An upright fridge is a much better option, as for temp control delete the thermostat and install an STC1000 (ebay $12) install a small computer fan and heater and it's just a case of set the STC to whatever temp you want, my Westinghouse 340 Ltr fridge only no freezer ($80 marketplace on facebook was also on gumtree) crash cools at -1c I've never set it lower so have no idea how low it can go, and ferments at 35c, it accomodates 4 kegs or the 55Ltr Fermzilla easily (120cm high, 50cm wide, 48cm deep) and serves as a 4 banger serving fridge at party time.


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## Paper Cowboy (15/8/19)

Muz said:


> I'm still trying to work out my fermentation temperature control.
> 
> I had decided to bite the bullet and buy another freezer for fermentation temp control. I've been looking for a second hand upright freezer on gumtree as I like the idea of just opening the door and doing gravity transfers, bottle straight from the fermenter etc. and this isn't possible with a chest freezer. Problem is all the upright freezers I'm seeing have chill coils in the shelves so they can't be removed to fit my brew bucket.
> 
> ...



Hey mate, a bit of advice if you have an inkbird and a basic fridge.

If you have access to the thermostat sensor which is attached to the evaporator (cooling plate inside the fridge, usually at the back) you can unattach it from the evaporator and let it free hang in the air. This means the fridge won't realise it's down to temperature and continually run. I'll post a picture of mine when I get home.


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## Paper Cowboy (15/8/19)




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