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  1. #1
    Join Date
    Mar 2006
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    1,032

    time to pull down to tem p?

    Ive got a few Mccall stand up freezers, just wondering if manufactures even post this type of info. I know it would vary with outside temps but just a rough idea.
    mo = 4-4020f01c

    Ive got many of this freezers and a few that ive worked out, seems to take along time to pull down to the desired temp of 0 degrees.

    Have Danfloss compressors which ive been told are garbage too.

  2. #2
    Join Date
    Aug 2007
    Location
    Winter Haven, FL
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    4,379
    An empty box is going to take a long time to pull down. You are dealing with a large volume of air to bring down in temp. Along with the walls and shelves. If you fill the freezer with frozen items and take up a lot of the volume, the temp drop time will decrease.
    i have seen some true freezers that were just about incapable of pulling the empty box below - 5f. But fill them up and it sits at- 10f all day long..

  3. #3
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    673
    Quote Originally Posted by Joe Harper View Post
    An empty box is going to take a long time to pull down. You are dealing with a large volume of air to bring down in temp. Along with the walls and shelves.
    I've read this same thing before on this site. I agree with some of what you said but disagree with some as well.

    After I fix a unit, I let it run with no product and it pulls down very quickly. Just last month I fixed a 2-door upright True cooler and after restarting empty box, it pulled down from 80*F to 35*F in like 10-15 minutes. Today I fixed a single door True cooler and it dropped below 40 within 10 minutes (empty).

    Last week I fixed a beer cooler that had been down for a week and filled with hot beer bottles. After repairing unit, it took over 45 minutes just to get to like 50*F because all the beer was hot.

    I agree that if you load the box with frozen food straight out of the walk-in-freezer, it will cool down quick. But I think the reason is because the cold food is absorbing heat along with the refrigeration system, so you instantly drop the heat load, and this makes the thermometer drop quickly. I don't think that it pulls down quicker because there is less volume air to cool off. Doesn't really matter why it works, I guess, I just like to analyze and think out loud .

  4. #4
    Join Date
    Jan 2003
    Location
    Olathe Kansas
    Posts
    246
    Quote Originally Posted by trippintl0 View Post
    I've read this same thing before on this site. I agree with some of what you said but disagree with some as well.

    After I fix a unit, I let it run with no product and it pulls down very quickly. Just last month I fixed a 2-door upright True cooler and after restarting empty box, it pulled down from 80*F to 35*F in like 10-15 minutes. Today I fixed a single door True cooler and it dropped below 40 within 10 minutes (empty).

    Last week I fixed a beer cooler that had been down for a week and filled with hot beer bottles. After repairing unit, it took over 45 minutes just to get to like 50*F because all the beer was hot.

    I agree that if you load the box with frozen food straight out of the walk-in-freezer, it will cool down quick. But I think the reason is because the cold food is absorbing heat along with the refrigeration system, so you instantly drop the heat load, and this makes the thermometer drop quickly. I don't think that it pulls down quicker because there is less volume air to cool off. Doesn't really matter why it works, I guess, I just like to analyze and think out loud .
    It's easy to get to 30deg. but after that the closer you get to zero the longer it takes.
    We have about 200 of the old 4020F's and yes some are really slow.

  5. #5
    Join Date
    Aug 2007
    Location
    Winter Haven, FL
    Posts
    4,379
    Quote Originally Posted by trippintl0 View Post
    I've read this same thing before on this site. I agree with some of what you said but disagree with some as well.

    After I fix a unit, I let it run with no product and it pulls down very quickly. Just last month I fixed a 2-door upright True cooler and after restarting empty box, it pulled down from 80*F to 35*F in like 10-15 minutes. Today I fixed a single door True cooler and it dropped below 40 within 10 minutes (empty).

    Last week I fixed a beer cooler that had been down for a week and filled with hot beer bottles. After repairing unit, it took over 45 minutes just to get to like 50*F because all the beer was hot.

    I agree that if you load the box with frozen food straight out of the walk-in-freezer, it will cool down quick. But I think the reason is because the cold food is absorbing heat along with the refrigeration system, so you instantly drop the heat load, and this makes the thermometer drop quickly. I don't think that it pulls down quicker because there is less volume air to cool off. Doesn't really matter why it works, I guess, I just like to analyze and think out loud .

    I guess the necessary btu's required for for 12 cubic feet of air is the same as 6 cu feet, by what you are saying........

  6. #6
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    673
    Quote Originally Posted by Joe Harper View Post
    I guess the necessary btu's required for for 12 cubic feet of air is the same as 6 cu feet, by what you are saying........
    Not sure if you're being sarcastic or what, like trying to make me sound dumb? Hard to tell through the Internet so maybe I'm reading too much into it, but obviously you disagree with me?

    My idea (which I may be wrong, and am open to discussion) is that i don't care whether it is 6 or 12 cubic feet of air (and yes obviously the necessary btu's required to cool off 12 ft of air would be more than 6 cu ft.), this air has little mass and will give up its heat quickly. It's the box full of hot product that contains a massive heat load and will take time to pull down. Or on the other hand, loading a box full of frozen food will allow the air to quickly give up its heat into the food, causing a box to quickly pull down.

    Does that make sense? Again, I'm not saying this is fact. I'd love to hear some other opinions.

  7. #7
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    673
    Joe, after thinking about it more, I'm remembering a job I did in the past where we installed evaporators in a brand new custom cooler. Several different sized units had same size evaporators, and the little ones pulled down quicker than the big ones (all were empty at the time). The only difference in that scenario is the amount of air inside the unit, so I can see what you're saying, the more air in the unit the more of a heat load. Interesting stuff.

  8. #8
    Join Date
    Aug 2007
    Location
    Winter Haven, FL
    Posts
    4,379
    Im a little sarcastic (my momma is not around here to keep me in-line), I like to make people think.
    air is harder to remove heat from than other substances. It has a low specific heat rating, and thus is not a good conductor of thermal energy. Copper and water have high specific heats and thus are good thermal conductors.

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