DIY glycol inquiry

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Jtvann

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Hey all,

I'm about to start the glycol project and wanted to check in about the AC unit. I read on earlier posts to look for a 12k btu unit. A more recent post says that a 5k unit was used.

I'm not too worried about the speed to get to lower temps, as long as both units can get to the same lower temp.

Will the 5k unit be enough for me to get roughly 40 degrees below ambient, or 25 degrees.
 

SanPancho

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A gallon weighs 8.3 pounds. If you want a 40 degree drop thats 330ish btus per gallon of liquid. Add 10-20% for losses and lets say 400 btus per gallon. In theory you’re looking at enough cooling for 12 gals at 40degree drop with 5kbtu unit.
 
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Jtvann

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Thanks for the quick math. I doubt I'll be using that much fluid, so I might have a little wiggle room.

Just got a hit on an old window unit. Might be able to get this on the cheap.
 

SanPancho

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if its old and used its probably ok, but you want to get one with mechanical controls, i.e. a rotary knob. the digital ones require extra wiring to get them to work with a typical inkbird type temp controller.

you can still buy them new for cheap i think. but as proof of concept, maybe old one might be good idea.
 
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Jtvann

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Thanks again for the advice. I've got 2 to go look at now this afternoon. Both on sale for 25 dollars each.

Betting they aren't fancy for that price
 
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Jtvann

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So the AC is free so far. I've got it preliminarily torn down and testing. It is the electronic type, so additional wiring seems to be in my future.

The fan runs constantly while powered on, but the compressor keeps kicking off. For now, I've put a heat lamp near the thermometer to test it out.

I need a better cooler. Mines too shallow, leaving too much of the unit not submerged.

Ended up being a 6.5k btu unit. I'll leave it running a few hours and see what it does
 
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Jtvann

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Fail.... I put the wrong side in the cooler.

Water heated up nicely to 70 degrees.

Let's see if I can unrig this thing now
 
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Jtvann

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Bingo. Now were in business. Why don't more people do this. This is so freaking easy.

I'd suggest not buying a brand new AC right off the bat, but the learning curve is not steep at all.

Added benefit, I've now got a pretty good heater for my cold basement. Wife will love that.
 
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Jtvann

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Been running just shy of an hour. Has dropped from 70 to 36. Hoping I can get a few more ore degrees. I'll be happy with 30
 

augiedoggy

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if its old and used its probably ok, but you want to get one with mechanical controls, i.e. a rotary knob. the digital ones require extra wiring to get them to work with a typical inkbird type temp controller.

you can still buy them new for cheap i think. but as proof of concept, maybe old one might be good idea.
depends on how you plan on controlling it. That is the opposite of what I was told by coolbot, something about how the digital ones are designed to be turned on and off differently with the digital thermostat and the knob ac units will not work correctly with a digital electrical thermostat.

all one needs to do is cheat the built in thermostat on a digital model. otherwise if you kill and reactivate power to the whole ac unit each time you need to make such proper delays are set in the stc or controller for the compressor.
 

SanPancho

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Iirc the original diy builds showed mechanical. Wired the system into always=on and then used inkbird/itc/etc. for start/stop via the controllers glycol temp reading, not the ac unit’s. Coolbot changes the story i believe as it uses the ac unit’s reading and “tricks” it by heating the temp sensor, no? Been a while since i looked at a coolbot but that was my understanding.
 
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Jtvann

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So there’s a pretty long and flexible temperature probe on my unit. I set the unit to the coldest it could go, 60, then ran the temp probe around to the back exhaust where warmer air blows out. Unit thinks it’s warm all the time that it runs and kicks the compressor on.

I didn’t need to do any rewiring at all. AC plugs into my ranco, that has temp probe in glycol.
 

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I’m looking into building my own glycol chiller to cool 2-3 5 or 10 gallon conical fermenters to different temperatures and following this thread for ideas.

Has anyone had success using a stainless coil in a small fridge or freezer to chill the glycol rather than the ‘normal’ DIY ac unit route? I feel a fridge might work just to chill the glycol for fermentation temp control but not for cold crashing and lagering. Has anyone tried hacking a small fridge with an ice box to maintain a temp of close to 30F and put a stainless coil in there for chilling the glycol reservoir.

I suspect the math doesn’t work out but I am sure there are more qualified people on this forum to answer the question.

Paul
 

Vale71

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I use a chest freezer to cool one single 14 gallong fermenter. I wouldn't even try it with 2 or 3 as the power won't be nearly enough to maintain fermentation temp in the summer, forget about lagering.
For it to work you need to literally fill the freezer with glycol mix as the fluid needs to come into contact with the freezer walls, where the evaporator coils are. If you try and cool the glycol any other way, be it in a bucket or keg or whatever, you'll fail as you'll be trying to use air, one of the best known insulators, to transfer heat and that simply cannot work.
 

augiedoggy

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I’m looking into building my own glycol chiller to cool 2-3 5 or 10 gallon conical fermenters to different temperatures and following this thread for ideas.

Has anyone had success using a stainless coil in a small fridge or freezer to chill the glycol rather than the ‘normal’ DIY ac unit route? I feel a fridge might work just to chill the glycol for fermentation temp control but not for cold crashing and lagering. Has anyone tried hacking a small fridge with an ice box to maintain a temp of close to 30F and put a stainless coil in there for chilling the glycol reservoir.

I suspect the math doesn’t work out but I am sure there are more qualified people on this forum to answer the question.

Paul
yes, theres a few threads on that here with reports it does in fact work with limited success.. its just not very efficient. the best sucess was with the coil in a bucket of water in the fridge or freezer.
 

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Thanks. As I suspected and I don’t want to put time, energy and money into a marginal system.

I am not in Texas with a fermenter in 100+ temperatures - fermentation will be in an air conditioned finished space and I’d like to size a system that will cool and crash a couple of 6 gallon conicals or brew-buckets. I would ‘manage’ the cooling so that only one fermenter would be crashing at a time. Will a 6 or 8,000 btu AC unit provide the glycol chilling capacity if the evaporator coils are in direct contact with glycol in a cooler? What sort of size cooler should I be looking at? In other words how many gallons of glycol would I need in the system?

Thanks. Looking forward to this project.

Paul
 

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Works like a charm . I have 3 gallons of glycol and 7 gallons of distilled water.
 

augiedoggy

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Thanks. As I suspected and I don’t want to put time, energy and money into a marginal system.

I am not in Texas with a fermenter in 100+ temperatures - fermentation will be in an air conditioned finished space and I’d like to size a system that will cool and crash a couple of 6 gallon conicals or brew-buckets. I would ‘manage’ the cooling so that only one fermenter would be crashing at a time. Will a 6 or 8,000 btu AC unit provide the glycol chilling capacity if the evaporator coils are in direct contact with glycol in a cooler? What sort of size cooler should I be looking at? In other words how many gallons of glycol would I need in the system?

Thanks. Looking forward to this project.

Paul
a 6,000btu ac unit is enough for multiple conicals or buckets.
 
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