Fermentation chamber not getting cold enough

[mdunlap85]

Hello! If this was answered elsewhere I have looked everywhere and I can't find the answer so please accept my apology and link me to the solution.

The chamber lives in my detached garage. It is powered by a large dorm fridge and a fan. The temperature controller is an inkbird with a stainless submersible probe. The insulation is foam board, aluminum covered 1" thick.

I have a fermentation chamber large enough to house two speidel 60L fermenters (roughly 4h x 5L x 3w). Up until this summer (which has been insanely hot, zip code 19809 for those interested) this chamber has served me well and I could get it into lager territory on a cool day, but it always got me to ale fermentation temps on a hot day (maybe not AS hot as this summer...). I was fermenting in the typical ale pales, during this time the chamber was top loading. I bought myself some 60L speidels and when I did this I had to alter the design of the chamber to be front loading.... It was around this time I noticed a dramatic drop in efficiency... My fermentation temperatures spiked to 90 in 90 degree heat. I spent a few weeks closing any possible air gaps I could find with spray foam, sponge foam, and aluminum tape. This improved matters quite a bit but I'm still seeing the fermentation temperatures in the high 70's. spent some time on a 90 degree day with my laser thermometer shooting every seam in the chamber and I can't locate a leak anywhere....

Finally my question: how do you know when you need to upgrade your fridge and do you have any recommendations? If I replace it with an air conditioner I fear it will short cycle or freeze up.... I'm at wits end here, if you can help or need more information please let me know.

 

[didinho]

did you try to put some iced bottles of water, to help the chamber reach the desired temperature?

 

[TheGoatman]

What modifications did you make? Are you fermenting in the chamber now, or just testing it out empty? If you made the chamber larger, there will be more surface area for the the heat to try and penetrate. If you're fermenting in it now (and are fermenting in larger batches) they would be creating more heat as it ferments than it used to in smaller batches, which would add to your problem. Did you move the fridge at all? Have you given the fridge a break and try to start it back up fresh? You would be able to tell it's just the fridge by putting the door back on the fridge and seeing if it gets back to fridge temps within it's own cavity.

 

[madscientist451]

Finally my question: how do you know when you need to upgrade your fridge and do you have any recommendations? If I replace it with an air conditioner I fear it will short cycle or freeze up....

If you are struggling with maintaining desired temperatures, you have a few options:
--Like someone already said, freeze 2 liter bottles of water and put them in to help out on the really hot days.
--move the fermentation chamber to a cooler place, maybe inside your house if its air conditioned.
--Avoid fermenting in the hot part of the year.
--Add more insulation
--Get a bigger compact refrigerator and fit that to you existing chamber, a small upright freezer would be better.
--To use a window A/C unit, people have used a product called CoolBot:
https://www.storeitcold.com/ I've never tried one, so can't offer advice, seems like getting a small upright freezer to fit your chamber would be you best choice, or just get a large freezer and forget the homemade chamber.

 

[TurnipGreen]

I built a son of fermentation chamber. This is my second summer season using it. Like folks before me said frozen soda/juice/whatever bottles are really helpful to hit a target temp in the summer heat. The interesting thing I noticed too it that it makes a big difference if you leave the bottles in the chamber even after they are thawed. I'm assuming this is because all that space they occupy with water helps regulate the temp better that dead air.

If your chamber is big enough for 2 60 L fermenters try one or two 5 gallon buckets of ice or ice water.

 

[mdunlap85]

Excellent suggestions, thank you.

I had an insulation expert (as luck would have it I have one in the family) have a look and he said my problem is almost certainly the fridge. It's a little older but I'm noticing the tray (the thing responsible for getting cold) is freezing up.... This never happened before and I think it might be my problem... This is my third year with this fridge, and the box it is attached two has not gotten any bigger, I just moved the door from a chest freezer style lid to a swinging door style (I cut the front in half, secured the half that is nearest the fridge and attached a couple hinges, and turned the other half into a swinging door). I've looked into the cold bot and that might be worth trying... I worry that my chamber is too small and the air-conditioner might short cycle. I've thought about turning a corner of my garage into a walk in chamber and hooking up a cold bot....

I'll give the buckets of ice a try, but it think I need to replace this fridge. thanks.