Home Made Glycol Chiller from A/C unit

Looking for some help on this project. I just opened up the wiring box in my A/C window unit to find a birdsnest of wires, a capacitor (not even sure how these work!), and a circuit board.

I am looking for help in rewiring this so that when I plug in the A/C, both the compressor and the fan will turn on high, bypassing the temperature probe's input, and bipassing me having to hit the "power" button on the a/c control panel. I drew out all the wiring that I could see to post here if anyone could help me.

Why do you need it to go on high?

Well It will be dual purpose serving my conical fermentor and as a future way to chill wort, so why choose low? I see what you are saying though- as the high/low is just the fan speed pushing air across the heat radiator and doesn't have anything to do with the compressor. Honestly high or low if anyone could help with the wiring I'd be thrilled!

More importantly, how will this chill Glycol?

I don't actually know anything about glycol chillers.

I've seen one before, but fu(k if I can find it now. The guy put the ac evaporator coils in a big cooler full of a glycol/water mix (so it wouldn't freeze on the coils). The glycol was then pumped through one side of a plate chiller. The hot wort was pumped and re-circed through the hot side of the chiller. You could also pump the glycol mix through an IC, although any leak there would cost you your batch.

Bingo! But I can't figure out the wiring! Anybody?

raceskier said:

I've seen one before, but fu(k if I can find it now. The guy put the ac evaporator coils in a big cooler full of a glycol/water mix (so it wouldn't freeze on the coils). The glycol was then pumped through one side of a plate chiller. The hot wort was pumped and re-circed through the hot side of the chiller. You could also pump the glycol mix through an IC, although any leak there would cost you your batch.

Click to expand...

I built one of these to cool my conicals. The evap coil goes in a cooler full of glycol/water and two pumps. Each pump has a temp controller that is monitoring each of my fermenters. The pumps pump the glycol through a copper coil wrapped around the conical. I can control temps within 1* all the way down to 34* even in the summer.





Anyway, for your project you'll need to do away with the electronics board. Are you using a temp controller to monitor the glycol bath? You'll need to. You'll also need a small pump in the glycol bath to keep it moving or it'll still freeze around the evap coil. I also highly recommend you paint the steel part of the evap before you ever get it wet, otherwise it rusts like a ***** and will eventually wreck your circulation pumps. Use the temp controller to connect the black in to the black to compressor and red on fan and one leg of the bath pump. Leave orange on fan disconnected. The temp controller will turn on the fan, pump and compressor at the same time. Connect the other side of the bath pump to the white cluster.

Oh and for chilling wort, I just have another coil inside the glycol bath with a bypass valve. I have hose water straight-thru something like this:

Water in -> shut-off valve->tee to coil -> bypass valve -> tee from coil-> to chiller.

So, for the first 100* or so I leave the bypass valve open. Once I hit ~110*, I shut the bypass valve forcing the water through the coil in the glycol and I can send 32* water to the IC. Make sure you blow all the water out of the coil afterwards or it'll freeze.

DISCLAIMER: I'm not an electrician or an HVAC/R tech. If you follow my advice you could be taking your life into your own hands. Electricity and water or any fluid for that matter are very bad together.

One other thing I came across while researching was this: It is NOT recommended to submerge single walled evaporator coils. While they are under pressure in a working system, they are on the 'low' side of the compressor. Should the evap fail or be compromised, it could eventually suck-in and try to compress water which would result in a catastrophic failure including ejecting the terminals from the compressor. This could easily kill anyone in the path of the terminals.

Having said that, the commercial glycol chiller I was looking at had a single wall evap coil submerged in the glycol.

To prevent rust, do you think diluting 100 percent propylene glycol with 90 percent isopropyl alcohol woud work for you? I don't know because there is still some water content left in the IPA, but it might help. It's my understanding that you can't use 100percent propylene glycol because of it's viscosity... Thanks for the witting diagram help!

Derrin, that is such a nice setup! Are your conicals both custom work? I don't recall seeing ferrules as racking ports on any B3s or Blichmans. Or I could just have a bad memory. Are those conicals 21 gallons? Pretty nice stuff! That's a shame that your glycol is clogging your pumps up with rust... I didn't think of that, but after looking at my a/c coils, I see the galvanized housing holding all the aluminum... Have you found a solution to your rust? I wonder about just cooling pure propylene glycol down to 25 degrees if it would be too thick to pump. Overall, how do you like your setup? Looks really sweet!

My conicals are B3 Pro Series 12.2's. I think had I just spray painted the evap black before ever immersing it everything would have been fine. Most of the time I don't bring it below freezing, so I actually don't run glyhcol often. Polypropelene glycol doesn;t have rust inhibitors in it, only the very toxic ethylene (sp) glycol (antifreeze) does.

I don't have a solution to my rust issue, but it has cost me 2 X $50 pumps :-( but at least I got 2 years out of them. I'll do it different next time.

Derrin said:

My conicals are B3 Pro Series 12.2's. I think had I just spray painted the evap black before ever immersing it everything would have been fine. Most of the time I don't bring it below freezing, so I actually don't run glyhcol often. Polypropelene glycol doesn;t have rust inhibitors in it, only the very toxic ethylene (sp) glycol (antifreeze) does.

I don't have a solution to my rust issue, but it has cost me 2 X $50 pumps :-( but at least I got 2 years out of them. I'll do it different next time.

Click to expand...

Since your stated you don't bring it below freezing and the glycol becomes thicker, instead of using glycol I would try soluble oil in your system. It has rust inhibitors in it plus is as thin as water as it is added to water. I will looks like low fat milk. and just as thin after it is mixed with water. It's used in machine shops a coolant for band saw blades, milling machine end mills, drill bits as well cooling the lathe tool bits. Heck I ran it instead if anti-freeze in radiators for years. Just another option to think about.

That's not bad idea, it would certainly solve the rust issue. Even though there is no risk of contamination with my design since the coil is never near the beer (outside the conical); I was not comfortable with non-food-grade products and so I never looked past polypropylene glycol. I buy the stuff from Pep Boys that is used to winterize the potable water supply on an RV, unfortunately there are no rust inhibitors in it though.

I think had the evaporator been well painted prior to ever being immersed, I probably never would have had a problem. It took about 2 years of service to destroy the pumps and with the new pumps I pump filters on the inlets to make sure no rust particles make it into the pump. So far so good.

One other thing; viscosity does not seem to be an issue. I've never run stronger than about 5:1 water to glycol. It's difficult to get the bath much golder than 25*. The reason being that even with a circulation pump, the evaporator starts to ice over and the forms a great insulator between the super cold coil and the bath. Off the top of my head i think the boiling point of R22 is -40*

What about using 100% pure glycol. I don't know how viscous it is, and if it really matters for our purposes... but it wouldn't allow any rust, or would it?

It would end up getting expensive and i'm not sure it would eliminate rust. If you just paint the evap with several coats of Rustoleum I think you'd be just fine and you could run just water if you chose to.

Or, if you can remove the pot metal end brackets without damaging the coils, that would be good too. The aluminum fins aren't going to rust. It's just the pot metal frame supports.

The two replies above, one to use 100% glycol. This will reduce the heat transfer which you are looking for in this design. straight water has the best heat transfer removal. The other reply about paint, paint is more of a insulator again defeating what your trying to accomplish that is to transfer heat off a surface into a coolant.

BrewBeemer said:

The two replies above, one to use 100% glycol. This will reduce the heat transfer which you are looking for in this design. straight water has the best heat transfer removal. The other reply about paint, paint is more of a insulator again defeating what your trying to accomplish that is to transfer heat off a surface into a coolant.

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Based on the few years I've been running mine, the insulation from paint would be insignificant. The coils get extremely cold and it just wouldn't be an issue. The ice block that forms on the evap coil is a much bigger insulation problem because then the bath is only exposed to ~30-32* ice and will never get colder. Circulation of the bath helps, but the evap gets so cold that it starts freezing the water out of the glycol at the contact surface. It all still works fine and I don't consider it a problem, just pointing out that paint would make no practical difference.

This is a photo when I was doing some initial testing a few years back. This is just water, but you the results are the same with glycol just at a slightly lower temp. More glycol would of course help but again, I can get my entire fermenter down to near freezing without much trouble.

Damn, your sure getting the temps down there. Most the time these cooling systems are 10-15 degrees higher than the manufactures claim they go down to. On the paint as a insulating material a long time friend in the radiaror business (over 60 years) he has seen show cars with a gloss black buildup of paint and they had overheating problems. Not to smart but in general many street rodders are not. "It's the look they are after". Yesterday I picked up a white food grade 55 gallon plastic drum.
I was thinking about filling it with cold well water circulating the HLT water thru it. In the HLT the 50' of 1/2" SS HERMS coil circulating the wort back thru the boil keggle for cooling and whirlpooling. Items come up free I grab them even if I do not use them later. I have two window AC units in storage that must weigh 230 pounds each. Saving them for another idea if needed.

Derrin said:

I built one of these to cool my conicals. The evap coil goes in a cooler full of glycol/water and two pumps. Each pump has a temp controller that is monitoring each of my fermenters. The pumps pump the glycol through a copper coil wrapped around the conical. I can control temps within 1* all the way down to 34* even in the summer.

Anyway, for your project you'll need to do away with the electronics board. Are you using a temp controller to monitor the glycol bath? You'll need to. You'll also need a small pump in the glycol bath to keep it moving or it'll still freeze around the evap coil. I also highly recommend you paint the steel part of the evap before you ever get it wet, otherwise it rusts like a ***** and will eventually wreck your circulation pumps. Use the temp controller to connect the black in to the black to compressor and red on fan and one leg of the bath pump. Leave orange on fan disconnected. The temp controller will turn on the fan, pump and compressor at the same time. Connect the other side of the bath pump to the white cluster.

Oh and for chilling wort, I just have another coil inside the glycol bath with a bypass valve. I have hose water straight-thru something like this:

Water in -> shut-off valve->tee to coil -> bypass valve -> tee from coil-> to chiller.

So, for the first 100* or so I leave the bypass valve open. Once I hit ~110*, I shut the bypass valve forcing the water through the coil in the glycol and I can send 32* water to the IC. Make sure you blow all the water out of the coil afterwards or it'll freeze.

DISCLAIMER: I'm not an electrician or an HVAC/R tech. If you follow my advice you could be taking your life into your own hands. Electricity and water or any fluid for that matter are very bad together.

Click to expand...

Derrin: I am getting set to start a similar project, and I am hoping you have dabbled enough to answer a question for me: My fermenters will be stored in a Michigan garage year round. This means that my system will need to both cool and heat the fermenters to maintain the temperatures I require for fermentation. I planned to use a dual temperature controller (activates 1 outlet above a certain temp, another below). I have been debating ways to heat the glycol. My first instinct is to simply install a heating element into the cooler containing the media. However, I am not sure how safe this is. I know the flash point of the RV anti-freeze is pretty high, but I am not sure if exposing it directly to a heating element is safe... Any ideas would be appreciated. Thanks!

Phill

phillc said:

Derrin: I am getting set to start a similar project, and I am hoping you have dabbled enough to answer a question for me: My fermenters will be stored in a Michigan garage year round. This means that my system will need to both cool and heat the fermenters to maintain the temperatures I require for fermentation. I planned to use a dual temperature controller (activates 1 outlet above a certain temp, another below). I have been debating ways to heat the glycol. My first instinct is to simply install a heating element into the cooler containing the media. However, I am not sure how safe this is. I know the flash point of the RV anti-freeze is pretty high, but I am not sure if exposing it directly to a heating element is safe... Any ideas would be appreciated. Thanks!

Phill

Click to expand...

Hi Phill,

You could do a couple things. On mine, I have these thin film heaters that are taped ti the cone with aluminum tape. They are low wattage 110V and work great. I have 3 per cone wired in parallel. Unfortunatly, I got them from a surplus dealer and they are no longer available.



The second option I would choose is using a couple 300W or so aquarium heaters in the glycol bath. They are fully submersible and very safe assuming they aren't allowed to run dry.

As a third option, you could even put them through the lid of the conical assuming you could find a grommet that would allow a snug fit of the heater and you always had enough wort in there to submerse the end of the heater. They are glass and easily sanitized.

Derrin said:

Hi Phill,

You could do a couple things. On mine, I have these thin film heaters that are taped ti the cone with aluminum tape. They are low wattage 110V and work great. I have 3 per cone wired in parallel. Unfortunatly, I got them from a surplus dealer and they are no longer available.

The second option I would choose is using a couple 300W or so aquarium heaters in the glycol bath. They are fully submersible and very safe assuming they aren't allowed to run dry.

As a third option, you could even put them through the lid of the conical assuming you could find a grommet that would allow a snug fit of the heater and you always had enough wort in there to submerse the end of the heater. They are glass and easily sanitized.

Click to expand...

The aquarium heaters are an excellent idea. Thanks!

phillc said:

The aquarium heaters are an excellent idea. Thanks!

Click to expand...

I have an old ac unit, I may have to build something when I get free time. :rockin:

FSR402 said:

I have an old ac unit, I may have to build something when I get free time. :rockin:

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Time, money and good health, get all three lined up and it's a green light project. I'm at a zero on all three now, sold one 230 volt AC unit that cooled a building inside a Sears building 24' x 36' on a remodel job, knock it down. Not free had to pay $5 for the AC unit. It was on a cart by my open garage of 380 sq/ft in a 98*F day I had 64 in the garage. It was too big to move and store. Sold it for $50 plus have two big window units to destroy if I need be, they weigh 140 plus pounds each.
I was thinking of adding a custom sized radiator to the front of the AC unit (a 60 year custom radiator friend will build it to any size for me free), duct cold air thru this radiator which will have a circulation pump with anti-freeze to the 50' x 1/2" stainless in the boil kettle. Many other uses also but I bet it would also spin the electric meter used beyond a boil chiller. BTU'S unknown.

Derrin said:

One other thing I came across while researching was this: It is NOT recommended to submerge single walled evaporator coils. While they are under pressure in a working system, they are on the 'low' side of the compressor. Should the evap fail or be compromised, it could eventually suck-in and try to compress water which would result in a catastrophic failure including ejecting the terminals from the compressor. This could easily kill anyone in the path of the terminals.

Having said that, the commercial glycol chiller I was looking at had a single wall evap coil submerged in the glycol.

Click to expand...

What does this mean for somebody putting together a system like this today? Are there some A/C units that have "dual layer" evaporator coils? What do we look for, specifically? How much of a risk is this, ie. how likely is failure? Obviously if the cooler was metal, there is a chance that vibration could cause rubbing that could eventually wear through the coil... Nobody is suggesting to use any coolant that is corrosive to the copper... I guess this is just the first I have heard of this concern, and I wonder what others are doing to minimize this risk....


Mylo

Derrin said:

I also highly recommend you paint the steel part of the evap before you ever get it wet, otherwise it rusts like a ***** and will eventually wreck your circulation pumps.

Click to expand...

Just a thought!

Instead of the pumps and dealing with the rust ruining pumps. Would using a small motor with a stirring shaft connected to it circulate the glycol enough to keep it from freezing.

Though the coil would still need to be painted or eventually it will rust away!

Add one of these guys from the aquarium world for your circulation, you'll never have a rust problem. I've used these forever in marine aquariums and they last forever.

http://www.marinedepot.com/ps_viewi...tent=HD00718&gclid=CNyTiYH5oMwCFQZkhgodLCQOYA