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Thread: Keeping cool

  1. #1
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    Keeping cool

    Little early to be thinking about it, but other conversations got me revisiting an old idea I've been kicking around for a few years.

    Now before I tell you about this you have to at least think about it some before you start laughing at me.

    The big drawback is of course the electricity consumed running AC. Lets face it a lot of shops just are not insulated well enough to even bother. The second drawback is maintenance. It's not easy keeping the sawdust out of a window unit.

    So whats it cost to run a small chest freezer?
    How about a circulation pump? The pumps cheap. the one on my outdoor boiler runs 24/7.

    So take an old freezer, fill it with old antifreeze
    put a circulation pump on it and cycle it through a heat exchanger like my boiler uses and blow air across it. Box the exchanger and the fan in, use some good filtration to keep the dust out. I've been kicking this idea around for a while now. I have a freezer, in fact it has food in it right now. In a few weeks I'm getting half a hog from my brother and I'm going to plug the new one in and move everything to it.

    All I really need is antifreeze and I can get that from the junk yard for 50cents a gallon for used stuff. I may have to add a few gallons of new to boost it a bit.

    Worst case scenario is it doesn't work. All I'll be out is $30 or $40 in antifreeze and a used freezer thats probably only worth $25 or so and a few bucks in fittings

  2. #2
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    Quote Originally Posted by Robert Mickley View Post
    ...Worst case scenario is it doesn't work. All I'll be out is $30 or $40 in antifreeze and a used freezer thats probably only worth $25 or so and a few bucks in fittings
    Based on that, I don't see any reason why you shouldn't try it.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  3. #3
    Don Taylor is offline Former Member (by the member's request)
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    Well, I have a friend who has a friend whose company makes insulation for refer cars. The man won't do it for just anyone but he allows my friend to come and get irregulars whenever he needs them. The stuff is three inches thick and comes in 4X8 sheets just like plywood. I don't know the numbers but it is suppose to be way up there better than the best stuff the contractors use for houses.
    He loaded up our two pickups and a trailer as high as we could go and charged us $17. This stuff is jammed tight between the 2X4's in all four walls and the overhead in my shop.
    I have a 24X24X12 shop and a 20,000 btu heat and cool air conditioner. Whether it is heat or cool, I've kept it on it's very lowest settings and it will either freeze or burn me out very quickly. The air conditioner doesn't actually run very much at all.
    I'm sure it will pick up its share of sawdust but I have two of the Jet air cleaner thingies. One hangs on the ceiling the other is a bench type that I keep close to me. Along with the DC system and the Festools, I'm not really concerned with clogging the air conditioner. (Although I do check it now and then.)
    By the way, that insulation is good for sound proofing too. I could hold my own St. Valentines Day Massacre out there and the neighbors would just keep on snoozing.

    Don

  4. #4
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    That insulation is the key thing, and you have it nailed Don!! I on the other hand have a shop thats not insulated so well and I live in a house trailer. neither one of which I own so cheap heating and cooling is must.

  5. #5
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    Robert, like Vaughn, I don't see a reason not to go for it. but keep in mind, that used antifreeze is going to be laiden with rust. It's coming out of old cars. Could have some oil in it also. The rust inhibitors in antifreeze break down over time, and that's why it gets dark (dirty) when it's 3 or more years old in your car. This rust could clog up your "radiator", and could deteriorate the inside of the chest freezer, if I understand correctly that you will be using it as a tank for the antifreeze. At a minimmum, it needs to be filtered well. And you need to find out what problems, if any, it will have on the material inside the freezer. You would be best to have radiators inside the freezer for the antifreeze to run through to collect the cold, where the antifreeze is, and let the pump circulate the fluid. That way the andifreeze never comes in contact with the freezer unless there is a leak. Most freezers get the cold air from the condensor of the cooling system by air, and therefore are not water tight. Another way to do this is to use lots of copper pipe in the freezer for the fluid to run through. But that's expensive also. Also keep in mind that the freezer puts out some heat during it's heat exchange.
    Keep playing with this idea. Just be careful with the fluid, you don't want to have it all over the floor in the shop, nor a leak outside that animals could get into. Jim.
    Coolmeadow Setters...
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  6. #6
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    see now you have the gears turning some more Jim.

    The local salvage yard saves antifreeze by draining it into 5 gallon buckets. The owners Dad is in a wheelchair and a couple times a week he goes through it and checks it with test paper. If is bad looking he doesn't even bother they just put it in the waste. I have a pump and filter head. I figured I would but the suction and return line into a drum and run it through a filter for a few hours. We used to do that with hydraulic oil back when I worked on construction equipment.

    Good idea on checking to see how it reacts with the freezer lining.

  7. #7
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    Robert, this is an interesting experiment but I don’t think it will work for what you need unless you invest more in your system.

    Freezers are made to attain a low temp in a small insulated compartment and then maintain it. The compressor pressurizes a refrigerant in liquid state and then releases it thru a nozzle. The refrigerant then becomes a gas and absorbs heat (latent heat of vaporization). When the refrigerant condenses to a liquid, the heat is released (latent heat of condensation). A freezer, refrigerator, or dehumidifier vents that heat to the room where the appliance is located, whereas an air conditioner vents that heat outdoors.

    You could either locate the freezer outdoors (insulated heavily), or move the condensation coils outdoors. Opening a refrigerant line is costly, so I don’t think that would be your first choice. Maybe the best way would be to locate the freezer in a cabinet on an exterior wall and power ventilate that space. Another possibility would be to strip the freezer all insulated cabinetry, vent the condensation coil heat outdoors, and blow air directly over the cooling coils.

    If you do pump antifreeze from a tank, maybe a Rubbermaid storage bin in the freezer compartment would work? Or maybe you could immerse the cooling coils in a Rubbermaid bin, and pump the antifreeze elsewhere?

    The difference in cost between running a freezer and an AC unit is because of the actual work being done and the efficiency of the appliance.

    FWIW, the first compressor in the basement shop I worked in was made from a walk-in cooler reefer, and we spray painted with the air. The tank was an old propane tank (Big no no). Eventually we had 80,000 sq. ft. and a rotary screw compressor, so I admire your willingness to start with the materials at hand.

    Wait ‘till Don Baer chimes in… he’s a real Joule for parsing stuff like this.

    Good Luck!

  8. #8
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    Actually Frank I was figuring on putting it in the same area as my outdoor boiler. Being there The heat from the freezer is not an issue.

    I do like the idea of a rubber maid tub though.

    One of the things to figure out is the difference in coolant temps. as in, just how cold is an AC coil? Ice cream that comes out of the freezer I'm planning on using is as as solid as a rock when it comes out. Which means it has to be in the neighbor hood of 5 degrees or so.

    hmmmm now that I think about this a freeze could be too cold. anything below 32degrees I may get icing problems on the exchanger in the house in a high humidity situation.
    Now I have to know just to answer that question

  9. #9
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    Robert,
    Think efficiency and conservation of energy. 1st of all for heating and cooling you must look at the definition of a BTU. 1 BTU is the amount of energy to heat or cool 1 lb of water 1 Degree F. If an AC is a 10,000 BTU AC then it consumes X amount of energy it will be the same regardless weather it is freezing anti freeze in the freezer or directly cooling air such as an air conditioner. In the case of a freezer like you envision the freezer must first cool the air in the freezer which will then cool the anti freeze. There are losses in every step of the operation. A double operation such as you are contemplating will have twice the looses as a single system It is impossible with the information you have at hand to estimate the losses but my gut tells me you'd be farther ahead just using a simple window AC to cool the shop.
    "There’s a lot of work being done today that doesn’t have any soul in it. The technique may be the utmost perfection, yet it is lifeless. It doesn’t have a soul. I hope my furniture has a soul to it." - Sam Maloof
    The Pessimist complains about the wind; The Optimist expects it to change;The Realist adjusts the sails.~ William Arthur Ward

  10. #10
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    Ok, I can see that Don. The biggest goal is to cool the trailer. If it doesn't cost anymore than running a whole house ac I can live with that.

    But more than anything I just have to see if it can be done. I'm one of those people, you can talk numbers all day long and I just get a blank look on my face. But take me out and show me and I go Even if it doesn't work I'll understand why. It's not that I doubt you. I just have to see

    It sort of like my outdoor boiler. Everyone who sells them said building one was a waste of time and it would never be efficient and it would end up costing more than store bought and would never work right.
    Well I proved that theory wrong. It smokes less than my neighbors, burns and just as long as his on a smaller load. His cost over $5000 mine cost me in the neighborhood of $1100 and a week to build.

    My theory is this, When my window AC units in the trailer are running the electric meter just spins like a top, both of them where new units two summers ago. I did some research and bought fairly decent units. Problem is I'm cooling a lossy trailer, so they run all the time.

    I figure on storing the energy in cold liquid, Like my boiler. IF, the fire goes out I have heat for twelve hours. In cold weather it takes that long for it to cool the 180 gallons of water from 170 to 120 degrees. In normal operation the firebox blower comes on when the water temp drops 10 degrees. it will run for about 20 minutes.

    So what I have to figure out is
    A: how to transfer the cold to the liquid efficiently

    B: figure out at what temperature that the cooling circuit cycles on and off in. Example, if its set to say 30 degrees at what temperature does it cycle on at and how long does it run to get back to 30 degree's.

    Well enough for now, I'm off to brothers for the day to help him clear a brush row.

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