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Thread: Homebuilt glycol chiller questions.

  1. #31
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    Mar 2016
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    AC glycol chiller conversion

    Just been experimenting with this recently. Took apart a 12,000 btu AC and put the evaporator in a cool box, and filled with water for my first experiment although next test will be with propylene glycol. Using an inkbird temperature controller to monitor the evaporator coil temperature (set at minus 4 oC) and turn the lamp on and off as a heat source which activates the AC temp probe next to it.
    My plan is to use the chiller primarily for cold crashing 500 lts of beer. I'm planning to buy an submersible aquarium pump which will be left on constantly to recirculate minus 2 centigrade glycol around the internal coils of the fermenter during cold crash.
    Any tips on this? I assume my 34 litre cool box will be large enough considering the pump will be on constantly allowing continuous heat exchange for the glycol with the evaporator coil.
    My one concern is, will the evaporator freeze up internally if it gets too cold? Say minus 10 centigrade?
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    Last edited by Fettucini; 08-30-2017 at 07:24 PM.

  2. #32
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    Dec 2016
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    Stockton, Ca. 95203. USA
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    Believe me it not worth the problems & cost !!!!

    Believe me it not worth the problems & cost !!!! Unless your a good AC teck. and have free parts, and want a something to do!!!

    Just buy the 3/4 hp UBC glycol chiller from Foxx Equipment for $1870,
    and move forward, and make beer...
    Gregg

  3. #33
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    Mar 2016
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    For us it is worth it. The cost of buying a glycol chiller here in Argentina is double that of Europe or US. I've read several reports of people doing it this way successfully for their breweries, and so far so good with this experiment.
    If anyone has any tips or experience with this, apart from not to do it, would love to hear!

  4. #34
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    Mar 2017
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    Redondo Beach, CA
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    glycol with rust inhibitors

    Commenting back a couple months later after switching to glycol (I originally used water and my system rusted to hell). I use a 5000 btu unit + small cooler at home for a couple small fermenters and my fermentation chamber and it works very well so far. In fact, I run a second cooler of water through a heat exchanger (copper tube) in my glycol to cool the water down and use that to keep everything at temperature. I do that because I don't need that much cooling power and don't want to get expensive glycol everywhere when I disconnect lines.

    To get rid of rust, I ran boiler water rust inhibiter for a week or two to dissolve any rust already on the system, then rinsed well and filled the cooler with 50-50 dowfrost with rust inhibitor and water. Not a spec of rust in there after a few months of on and off use. I can't comment on how effective glycol alone will be at preventing rust, but for the extra few dollars, it's nice to have piece of mind.

    I also don't know how well it will hold up with a larger system, but in a couple months I'll have a couple 3 bbl fermenters to test on so I'll try to remember to comment back then.

  5. #35
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    Mar 2017
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    Redondo Beach, CA
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    Quote Originally Posted by Fettucini View Post
    Just been experimenting with this recently. Took apart a 12,000 btu AC and put the evaporator in a cool box, and filled with water for my first experiment although next test will be with propylene glycol. Using an inkbird temperature controller to monitor the evaporator coil temperature (set at minus 4 oC) and turn the lamp on and off as a heat source which activates the AC temp probe next to it.
    My plan is to use the chiller primarily for cold crashing 500 lts of beer. I'm planning to buy an submersible aquarium pump which will be left on constantly to recirculate minus 2 centigrade glycol around the internal coils of the fermenter during cold crash.
    Any tips on this? I assume my 34 litre cool box will be large enough considering the pump will be on constantly allowing continuous heat exchange for the glycol with the evaporator coil.
    My one concern is, will the evaporator freeze up internally if it gets too cold? Say minus 10 centigrade?
    I think the standard people typically do is -3C set temperature with about a 6C delta for it to kick back on (+3C). When you have glycol in there you can push the temperature lower since it's antifreeze, but the problem then becomes icing inside your fermenters.
    Forgot to mention, I think that size cooler will be fine. I use a smaller AC unit (5000btu) and slightly larger cooler and it works great. Worst case, the AC will kick on a few times during cold crash and it should maintain temperature fairly easily. Insulate your lines if you can to reduce soaking up heat and condensation.
    Last edited by drestauri; 09-01-2017 at 08:53 AM.

  6. #36
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    Quote Originally Posted by drestauri View Post
    Commenting back a couple months later after switching to glycol (I originally used water and my system rusted to hell). I use a 5000 btu unit + small cooler at home for a couple small fermenters and my fermentation chamber and it works very well so far. In fact, I run a second cooler of water through a heat exchanger (copper tube) in my glycol to cool the water down and use that to keep everything at temperature. I do that because I don't need that much cooling power and don't want to get expensive glycol everywhere when I disconnect lines.

    To get rid of rust, I ran boiler water rust inhibiter for a week or two to dissolve any rust already on the system, then rinsed well and filled the cooler with 50-50 dowfrost with rust inhibitor and water. Not a spec of rust in there after a few months of on and off use. I can't comment on how effective glycol alone will be at preventing rust, but for the extra few dollars, it's nice to have piece of mind.

    I also don't know how well it will hold up with a larger system, but in a couple months I'll have a couple 3 bbl fermenters to test on so I'll try to remember to comment back then.
    I've had the evaporator sitting in the cooler full of water for a week now and no signs of rust. I think though that the fins on this unit are made of aluminium or some other metal though as should be seeing signs of rust by now otherwise.
    The other thing is, this AC unit came with two temperature sensors, one as the standard one on the front, and another which was slotted in on the side of the evaporator (which i removed there and let hang outside the unit). Any ideas what this one on the side is for? I assumed it was for ensuring the evaporator coils don't get too cold.. then that made me wonder, what is a safe temperature you can bring the evaporator coil down to without causing problems for the AC unit?
    I set the inkbird temp controller at minus 4 centigrade when i was testing with water in the cooler, with a 0.5 centigrade spread to turn the temp probe heat source (a lamp) on or off. Seems like there's a delay of aproximately 3 minutes though that the compressor can switch itself on again after being switched off. Is that normal? I read it could be an inbuilt safety measure into the AC.
    Last edited by Fettucini; 09-02-2017 at 11:19 AM.

  7. #37
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    Oct 2014
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    Kent, WA
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    301
    Quote Originally Posted by Fettucini View Post
    [...] and another which was slotted in on the side of the evaporator (which i removed there and let hang outside the unit). Any ideas what this one on the side is for? I assumed it was for ensuring the evaporator coils don't get too cold.. then that made me wonder, what is a safe temperature you can bring the evaporator coil down to without causing problems for the AC unit?
    Most likely it's to detect icing, so the A/C can run through a defrost cycle. I believe the evaporator temperature depends on the type and quantity of refrigerant, measured by the running pressures. On a typical A/C, this is not adjustable or even measurable without cutting into the refrigerant lines.

    Regards,
    Mike

  8. #38
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    Mar 2017
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    Quote Originally Posted by Fettucini View Post
    I've had the evaporator sitting in the cooler full of water for a week now and no signs of rust. I think though that the fins on this unit are made of aluminium or some other metal though as should be seeing signs of rust by now otherwise.
    ...
    I set the inkbird temp controller at minus 4 centigrade when i was testing with water in the cooler, with a 0.5 centigrade spread to turn the temp probe heat source (a lamp) on or off. Seems like there's a delay of aproximately 3 minutes though that the compressor can switch itself on again after being switched off. Is that normal? I read it could be an inbuilt safety measure into the AC.
    Good that yours isn't rusting! Mine it wasn't the fins that rusted, but the support bars on the ends of the fins where you can see the copper pips go in and out of the fins. Those help keep everything stable since the fins and copper tubing themselves are both soft metals. On my unit, those are not made of aluminum and that's where it rusted.
    And yes, it's totally normal to have a delay to cycle the A/C. Most temperature controllers have that safety measure built into it as well. My controllers will only allow the cold power to turn on after 3 minutes or more of being off. It's to prevent cycling the A/C on and off too much which will wear it out.

  9. #39
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    Mar 2016
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    Quote Originally Posted by rdcpro View Post
    Most likely it's to detect icing, so the A/C can run through a defrost cycle. I believe the evaporator temperature depends on the type and quantity of refrigerant, measured by the running pressures. On a typical A/C, this is not adjustable or even measurable without cutting into the refrigerant lines.

    Regards,
    Mike
    Yeah I noticed that when I remove the second temperature sensor from the side of the evaporator, the lines all ice up like in the pic. Is that a problem for the life of the AC? Baring in mind I set the temperature controller at minus 4, so the temperature of the evaporator seems to oscillate between about minus 7 and plus 3 oC.
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  10. #40
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    Quote Originally Posted by Fettucini View Post
    Yeah I noticed that when I remove the second temperature sensor from the side of the evaporator, the lines all ice up like in the pic. Is that a problem for the life of the AC? Baring in mind I set the temperature controller at minus 4, so the temperature of the evaporator seems to oscillate between about minus 7 and plus 3 oC.
    Honestly, I don't know for sure. I don't think it would harm the A/C, but in a coolbot type of install, you need it for defrosting. If the entire evaporator is submersed in glycol, maybe not. However, I will say that this probably depends more on the load on the A/C, and not the setpoint. Some years ago I got a call from a tanning salon that their A/C wasn't working. When I got there, the rooftop unit was a solid block of ice. But it was a hot day. As the load increased, ice began to form. Once the ice began to block air flow, the entire thing quickly iced up solid.

    So, you might get away with it, or you might find the evaporator temperature dropping so far that it will freeze your glycol mix on the fins, even though the bath temp remains higher. Even if the bath temperature is, say 0C, the evaporator must be colder, or heat would not flow through the system. As it works harder, the evaporator gets colder, even though the bath temperature may be going up (like the tanning salon example)

    I guess it depends on the type and quantity of refrigerant as to how low the evap temperature will go, but it would surprise me if it went low enough to freeze the glycol. I can't say for sure, though.

    Regards,
    Mike Sharp

  11. #41
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    Oct 2012
    Location
    Midland, Texas
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    How is everyone's Frakenchiller working at the moment? With few options for a used chiller, I am looking at going this route. Some help is appreciated....and a cost effective source for glycol too.
    I was thinking of using a 100 quart cooler and a 12.5 BTU AC unit.

  12. #42
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    Dec 2014
    Location
    Bend, OR
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    Quote Originally Posted by Mad Scientist View Post
    How is everyone's Frakenchiller working at the moment? With few options for a used chiller, I am looking at going this route. Some help is appreciated....and a cost effective source for glycol too.
    I was thinking of using a 100 quart cooler and a 12.5 BTU AC unit.
    That's what I used for a 7bbl and 3.5bbl unitank. Worked well although I would have to isolate each tank if one started off much warmer than the other. Once they were cold, it kept up nicely.
    For glycol, I went with: https://www.amazon.com/35-723-ProFro...Bprofrost&th=1

    Free shipping, it was the best deal I could find for low volumes.

    mtn

  13. #43
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    Oct 2012
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    Midland, Texas
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    Do you have a similar set up to the parts list earlier in this thread? Aside from bigger cooler and AC unit....Curious what type of circulation pump you are using and how your controller set up is wired. Does your pump run continuously?
    Last edited by Mad Scientist; 01-26-2018 at 10:54 AM.

  14. #44
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    Dec 2014
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    Bend, OR
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    Quote Originally Posted by Mad Scientist View Post
    Do you have a similar set up to the parts list earlier in this thread? Aside from bigger cooler and AC unit
    Pretty much the exact same thing. The hardest part for me was bending the cold side radiator to fit into the cooler without pinching or breaking the copper tubes. I also had a hard time trying to seal around the cutouts I made in the cooler, I couldn't find anything that stuck well (water tight) to the cooler plastic. I used a ranco temp controller for each fermenter with it's own solenoid. The supply pump ran all the time as I had a bypass on the line. I also added a submersible pump inside the cooler to keep the glycol well mixed. Worked great for 2 yrs or so.

    mtn

  15. #45
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    Quote Originally Posted by Mtnmann View Post
    Pretty much the exact same thing. The hardest part for me was bending the cold side radiator to fit into the cooler without pinching or breaking the copper tubes. I also had a hard time trying to seal around the cutouts I made in the cooler, I couldn't find anything that stuck well (water tight) to the cooler plastic. I used a ranco temp controller for each fermenter with it's own solenoid. The supply pump ran all the time as I had a bypass on the line. I also added a submersible pump inside the cooler to keep the glycol well mixed. Worked great for 2 yrs or so.

    mtn
    I just changed my cooler to a 65 litre from the 34 litre one before. Makes it expensive to buy enough propilen glycol to fill it, but the evaporator fits better and can now be fully immersed for cooling capacity.
    I resolved the issue to seal the cutout hole in the coolbox (where the evaporator pipes enter) using a two component expandible foam. I taped up the sides, mix the two components and poured it in.. it expands inside and fills all the cracks.. just did it yesterday and no leaks so far!
    Now just hoping my 12,000 BTU unit will be enough to cool it down to minus two centigrade. Need to be able to cold crash 600 litres a week!

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