Fridge Power Required For Cooling A Fermentation Chamber

[andy6026]

Hello everybody.

I've recently started building a custom-designed fermentation chamber and I'm halfway through the project.

However, I've suddenly got a sinking feeling that I may have made a huge oversight: I don't know if the mini-fridge I intend to use will be powerful enough for the size of the chamber.

The box is going to be approximately 4' wide, 2' deep and 2' high. I intend to house up to 4 fermenter buckets. The good news is that the my house is air conditioned and the ambient temperature doesn't rise about 71F. I intend to mostly ferment ales (low to mid 60s), but I'd also like to be able to cold-crash in this fermentation chamber.

I don't think the mini-fridge will have trouble keeping the chamber in the low 60s, but will I be able to cold crash with it? Thanks for your advice!

 

[RM-MN]

Hello everybody.

I've recently started building a custom-designed fermentation chamber and I'm halfway through the project.

However, I've suddenly got a sinking feeling that I may have made a huge oversight: I don't know if the mini-fridge I intend to use will be powerful enough for the size of the chamber.

The box is going to be approximately 4' wide, 2' deep and 2' high. I intend to house up to 4 fermenter buckets. The good news is that the my house is air conditioned and the ambient temperature doesn't rise about 71F. I intend to mostly ferment ales (low to mid 60s), but I'd also like to be able to cold-crash in this fermentation chamber.

I don't think the mini-fridge will have trouble keeping the chamber in the low 60s, but will I be able to cold crash with it? Thanks for your advice!

I don't think you will be able to get the beer super cold for cold crashing but time will do the same thing. Get the beer as cold as the fridge will allow. It might take an extra few hours over what getting the beer near freezing would take. I just leave my beer in the fermenter for 2 to 3 weeks and it clears up.

 

[GPP33]

A lot will depend on the design; how big the original fridge was, how well it’s insulated, how well it’s sealed and how well air can circulate. Getting 4 buckets to typical cold crash temps is going to a big chore for any small fridge though.

 

[andy6026]

I think you guys are both right: fermenting temps should be easy to achieve but cold crashing won't quite get there. It should be close enough. I just wish I could predict the future. An alternative might be to use a spare window-air-conditioner unit that I have lying around.

 

[TechFanMD]

If your box is well insulated I think you might be surprised. I would highly recommend having a fan to move air. My mini fridge can be 45F toward the top and 28F near the bottom and it takes a long time to cool a keg or bottled beers (if that's what I'm using it for at the time). I added a 12v PC fan and it is amazing how much colder it can get and is even throughout. It keeps air moving around everything - including the thermostat - which helps quite a bit.

I think the bigger issue is how much you're cooling at once. 4 buckets going from 68F to 32F all at once is a lot different than having 3 buckets in there at 40F and adding a 4th then trying to get to 32......there will be less air space and a lot of thermal mass - so a lot of it depends on how you're using it. I would make sure to always have 4 buckets in it - even if you just have some spare Home Depot buckets with water, to ensure there is little air space and you will have the thermal mass on your side (and make sure those placeholder buckets are cold before trying to cold crash).

Anything you do to insulate better, avoid opening it to peek (get a remote thermometer or temp controller), and keep air moving inside and you might be pleasantly surprised. You might even want to further insulate the sides of the fridge (not the coils side) better - they are not as well insulated as you think. Good airflow and/or assistance with an external fan around the coils can help a lot as well.

Did I mention to add a fan inside?