Gotta know for myself: Mini fridge chiller

[Sangmang]

Against the advice of several forum threads I'm gonna try it anyways. Instead of coils in the fridge I'll use cold water from the fridge to chill a wort chiller that sits in the nutrient res.

30gallon nutrient reservoir
1.7 cu/ft mini fridge
3/8" x 25' stainless wort chiller

I built and sealed a box that fits in the fridge to try to get as much water in there as possible. Tomorrow I'm going to line the inside with plastidip spray. Then I'll fill it with water and use a small pump and an inkbird control to circulate the cold water as needed. I had to cut the shelves off of the fridge door to make space for the box. Not sure how long the plywood will hold up in the fridge?

Im kind of expecting this to be not quite worth the effort but we'll see. If I can drop my res temps by 5 degrees F in the summer I'll be happy.

 

[Stormblessed]

So r u gonna drill a couple holes for an intake line and an output line and the box inside the fridge will b ur res? Pretty cool

 

[sneekymofo]

I might be missing something, but why WOULDN’T this work? I don’t know what the ultimate temp of the fluid that will be pumped through the wort chiller, but I would think it would bring down res temps just fine. Never tried it, but interested….

 

[Southerncough]

Or you could seal it with fiberglass/resin like a live well on a boat

 

[Southerncough]

I was kicking around a similar idea a while back to find a tote or bucket that would fit inside a mini fridge and cram a coil of copper tubing inside, fill it with icewater (for a head start) and let the fridge keep the res as cool as possible. The circulation pump would be in the res and there would just be two holes in the fridge for the water in/out.
What's nice about this build is the box is made to fit inside. Do you think a sturdy contractor bag could hold its form inside the box? As long as nothing sharp is poking through or stressing the bag I don't see why it couldn't serve as a liner. That or maybe some pond liner material from the garden center

 

[Sangmang]

I was kicking around a similar idea a while back to find a tote or bucket that would fit inside a mini fridge and cram a coil of copper tubing inside, fill it with icewater (for a head start) and let the fridge keep the res as cool as possible. The circulation pump would be in the res and there would just be two holes in the fridge for the water in/out.
What's nice about this build is the box is made to fit inside. Do you think a sturdy contractor bag could hold its form inside the box? As long as nothing sharp is poking through or stressing the bag I don't see why it couldn't serve as a liner. That or maybe some pond liner material from the garden center

Yeah I thought about pond liner but it's kind of expensive. I figured the rubber spray paint was the cheapest route if it works. It's pretty thick stuff.

 

[Sangmang]

I might be missing something, but why WOULDN’T this work? I don’t know what the ultimate temp of the fluid that will be pumped through the wort chiller, but I would think it would bring down res temps just fine. Never tried it, but interested….

It's possible the fridge will lose the battle trying to keep the water cold as it gets warm from circulating. Im sure it'll be able to drop the res temp for a little while at least. I think I'll have to insulate the res as well.

 

[sneekymofo]

It's possible the fridge will lose the battle trying to keep the water cold as it gets warm from circulating. Im sure it'll be able to drop the res temp for a little while at least. I think I'll have to insulate the res as well.

For sure less efficient than a chiller, but with a large volume of cold water you’ve got a lot of room to buffer the heat exchange. I don’t know how cold a fridge can get a volume of water, but I would imagine ‘pretty cold’ lol. I know no maths on thermodynamics and heat exchange, but there might be something out there in the Interwebs. Like I said, I’m kinda interested to see how this project turns out

 

[Southerncough]

what if you put a frozen bottle in the fridge container to give it a boost of sorts?
As for the fridge keeping up, I would probably put the circulation pump on a timer to give the fridge time to work etc.
Like 10 on 30 off, etc

 

[Sangmang]

Just finished 4 coats of Plastidip spray. Gonna let it dry for a few more hours and then see how it holds water.

 

[Braddah Waiheesohai]

A chest freezer would be more efficient if this works out and you move on to 2.0.

 

[Sangmang]

A chest freezer would be more efficient if this works out and you move on to 2.0.

Yeah for sure. If I could have found a tiny one like this fridge I would have went that route.

 

[Michael Hunt]

If it doesnt hold water, try lining it with pond plastic with all the open seams up at the top or folded over the top and secured to the outside.

 

[Spacebouquet]

You could always remove the evaporators from the fridge and align them, stacked against the current within the tank .. or make the water pass over all of them in series for more cooling efficiency.

 

[Hellbent]

Looking at this thread, it seams to me that you are doing much more work then you need to. To chill my res down to any temp you want, I set mine for 67 deg, here is what I do. I look at online market sites for a used water cooler, one you would put a 5 gal jug on top. I have bought 2 for about $30 each. I then dismantle it throwing away all the plastic so I am left with the compressor and the coil. Some coils have a plastic coating on them, the ones that don't I would just put a plastic bag over the coil and then just place the coil directly into your res. I then bought a devise that plugs into the wall that monitors the temp of your res $50. This devise also has 2 plug outlets labeled "heating & cooling" and will turn the compressor on and off according to what ever temp you have programmed into it. Make sure that your res is outside of your grow tent or room so the lights in your grow room are not heating up the res.