DIY glycol chiller questions

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philly224

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So I built a glycol chiller out of a 5000 btu window ac unit and put in six gallons of water and two of glycol into my cooler. First test run it got down from 70 degrees to 32 in less than an hour which really surprised me. I did stir it a few times to keep it circulating.

My questions are

1. Should I add some kind of pump or something to circulate the glycol solution in the cooler?

2. My coils are not completely covered, would adding another gallon of water hurt anything or would that throw off the glycol ratio too much?


Thanks in advance !
 

RiverCityBrewer

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I've built nearly the same thing and been using it for a few months now...

1) Yes, add a pump and tie it into the circuit to turn on when the AC is running... I've found that the AC coils can ice if there is no liquid movement around them. Your 70 to 32 drop should only take about 15-20 minutes at that volume if its recirculating. I have 6 gallons total in my cooler and my AC comes on for about 5 minutes twice a day to hold 28... cycles more often if I'm actually fermenting but rarely runs more than 5 minutes.

2) At full volume my coils are nearly covered, but my jacket on the conical holds a little over 2 gallons, so during fermentation the top third of my coils are exposed as well. I haven't noticed any detrimental effects, though I'm sure the cooling efficiency would be higher if I had them all submerged. Just know that as you add more water, your freeze point will rise, and depending on your set point and circulation situation, you could freeze on the coils.

Good luck.

Joe
 

SanPancho

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Adding a recirc pump adds heat to the glycol. Efficiency loss there. Unless you having cooling issues its not actually necessary. It depends on typical usage rates for system tho.

If you don’t wanna buy more glycol then just put something in the reservoir to take up space- think of the old brick in the toilet tank trick. Just put the brick in a ziploc. Dont want it messing up the glycol.
 
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philly224

philly224

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Adding a recirc pump adds heat to the glycol. Efficiency loss there. Unless you having cooling issues its not actually necessary. It depends on typical usage rates for system tho.

If you don’t wanna buy more glycol then just put something in the reservoir to take up space- think of the old brick in the toilet tank trick. Just put the brick in a ziploc. Dont want it messing up the glycol.
That's a good idea!

And right now I'll only have it hooked up to one five gallon conical, two eventually so usage won't be super high.

Does adding a recirculating pump decrease efficiency by a lot?
 

SanPancho

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Hard to say. Im not familiar with a setup on this scale.

One way you could sort of go halfway is to wire the pump to go on with the chiller. That way it helps mix the glycol in the reservoir to get everything cooling uniformly , then shuts off when the cooling stops so no more heat introduced.
 
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philly224

philly224

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What's the easiest way to achieve the recirculation pump going on with the ac unit?
 

SanPancho

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Depends on how your rig is set up. Maybe splice it to the AC condensor fan? Or where fan used to be if its gone.

Or if you are using an external temp controller then just add another plug.
 
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philly224

philly224

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Depends on how your rig is set up. Maybe splice it to the AC condensor fan? Or where fan used to be if its gone.

Or if you are using an external temp controller then just add another plug.
I am using an external temp controller so adding a new plug would probably be easiest as long as it doesn't block the heating plug on my inkbird. Thanks!
 

cegan09

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A tiny pump in the cooler will not add enough heat to care about.

I bought a 120V recirculation pump for an aquarium and secured it inside the cooler aimed at the coil. Mine is run to a switch so I can turn it on and off, but you could easily just tie it into the SSR/Relay/Whatever turns your AC unit on and off. Both at 120V AC so it would be as simple as wiring in parallel.
 

RiverCityBrewer

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I agree, I'm only using a little 8w submersible fountain pump to move the glycol around in the cooler, and it only runs when the AC unit is running. I'm sure it generates a little heat when its on, but it doesn't seem to affect the chilling power in a noticeable way.
 
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philly224

philly224

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I agree, I'm only using a little 8w submersible fountain pump to move the glycol around in the cooler, and it only runs when the AC unit is running. I'm sure it generates a little heat when its on, but it doesn't seem to affect the chilling power in a noticeable way.
Which one do you have if you don't mind me asking?
 

RiverCityBrewer

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The little pump I have for recirc I bought at Home Depot years ago, can't find it currently. However, I'm using this pump (http://a.co/3HuAitz) from amazon for actually pumping through my conical with good results, so I would be comfortable recommending its 90GPH sibling for use.

It also doesn't hurt that they are so cheap they are essentially disposable.
 
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philly224

philly224

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The little pump I have for recirc I bought at Home Depot years ago, can't find it currently. However, I'm using this pump (http://a.co/3HuAitz) from amazon for actually pumping through my conical with good results, so I would be comfortable recommending its 90GPH sibling for use.

It also doesn't hurt that they are so cheap they are essentially disposable.
Sweet thanks! Do you put any tubing on it?
 
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philly224

philly224

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Also another question, what do you guys keep the temp of the glycol mixture when you are trying to keep your beer at 66-68 degrees? I was thinking like 55ish and then dropping it down to 28 right before starting the cold crash.
 

RiverCityBrewer

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Yes, I put a piece of tubing on the pump and route it to the other side of the cooler.

As for temperature, I think it depends on if you are using a jacket or a coil. I have a jacket, so I can only speak to my experiences with that. I can push a little over 2 gallons into the jacket on a ~20gal conical, and I find that having about a 10 degree difference between my setpoint and the glycol temp gives me minimal overshoot when the system calls for cooling.
 
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