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Thread: Proper freezer temperature

  1. #1
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    Question

    What is the proper temperature for a kitchen freezer?
    (as opposed to a "deep-freeze" chest freezer commonly seen in basements, garages, etc.)

    my wife just picked up a fridge/freezer thermometer with temp ranges marked for fridge and freezer. The freezer range is marked for 0 to -10 farenheit, and she's a bit freaked because we've been keeping ours in the 15 to 20 degree range.

    I think our food has been fine, and that the zero-range must be for deepfreeze units. Anyone have any hard info on this?

  2. #2
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    My creaking old freezer stays at about 4 degrees (remote sensor)...it supprised me to be that cold.

  3. #3
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    I believe the recommended temperature is zero F.

    I have checked several cookbooks and they all say for storage over a week to keep at at zero, perhaps five degrees tops.

  4. #4
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    "The freezer range is marked for 0 to -10 farenheit, and she's a bit freaked because we've been keeping ours in the 15 to 20 degree range."

    15 to 20 is not good for frozen food purposes. I work on this stuff. In other words, frozen food vending machines. We try to keep everything at around -10 or below. The machines I work on have a "health control system" that interrupts the circuit and renders the machine out of service unless these temps are maintained. I'd turn it a little colder if I was you.

    Your are probably safe in the 15 to 20 degree range as far as bacteria are concerned but I'm just giving you an industry standard.

  5. #5
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    IIRC, most domestic refridgerator/freezers are capable of no more than 15-20F in the freezer compartment. That's the temp that is used to give "safe for up to x units" (ie: butter is safe for up to 3 months) recommendations. BTW, stuff lasts longer if freezer bags and/or double wrapping are used.

    For longer term storage (up to 1 year or so), you need a "deepfreeze".

  6. #6
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    "The freezer range is marked for 0 to -10 farenheit"

    If it's marked for 0 to -10, I'd turn it on that setting and see what it will do.

  7. #7
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    You really believe that because your car speedo is marked for 140 mph, it's capable of getting there?

  8. #8
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    The only temperature the USDA mentions is 0-F. Chicken and turkey isn't called frozen at 28 degrees, it takes much colder to actually freeze them. USDA guidelines

  9. #9
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    Originally posted by Meerkat:
    You really believe that because your car speedo is marked for 140 mph, it's capable of getting there?
    Do you believe what the thermometer in your refrigerator says?

  10. #10
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    I keep ours at 2 degrees F ... although it recommends 0 degrees F.

    I figure I am helping the environment by saving a few jolts of electricity every year! Ours will go down to negative 10 I believe.

    Now, the one I had built into the wall, under the stairs in the laundry room, goes down to Zero. And, it was just a basic lower-end model.

  11. #11
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    I've always heard it should be 0 F. Even the freezer in my boat can do that.

  12. #12

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    The way a frost free refrigerator works is this: There is only one compressor in a typical household refrigerator. It has to provide two very disparate temperatures within the same box, and does this in a couple of ways. The first one is that the cooling coils are concentrated in the freezer section and a fan uses only a portion of the air to cool the fresh food section. A second fan provides air flow throughout the freezer and blows it by the cooling coils to not only refrigerate the air, but to condense any moisture in the fridge onto the coil itself. Contained within the cooling coil area is a heater. It is activated by what is called the defrost timer every 8 hours to melt the frost off the coil, which then as water travels down a tube into the tray you see close by the compressor unit in the bottom of the refrigerator. The heat of the compressor evaporates the water in the tray into the air.

    The problem with frostfree refrigerators is this method of dispensing with the frost. During the defrost cycle the fridge compressor shuts off and the little heater does it's job. In the meantime, the temperature in both sections of the refrigerator alters as much as 8 degrees F. This is what spoils fresh food. Constancy in temperature very important for keeping many foods fresh for longer periods (more than a couple of days) The second problem is that by the nature of removing moisture from the air within the refrigerator, (typically they run at about 10-14% humidity) it also removes moisture from food. You can't leave lettuce or anything high in moisture uncovered or out of the sealed crispers provided or they will spoil extremely quickly. This is also the reason for freezer burn. The shift in temperatures combined with the dry air damages frozen food as well.

    Most refrigerators will run their freezers at about 5 degrees F, but that will vary with the defrost cycle anway. A fresh food section should be roughly 38-40 degrees F, but again variance will occur. High end refrigerators like SUB ZERO (from Madison Wisconsin) solve this dilemma by installing two completely separate refrigeration systems each with their own compressors, and running at distinctly different humidities. The fresh food section has superior temperature constancy which keeps food much fresher for longer periods.

    Bottom line: Keep meat products and anything that you want to keep frozen longer than a couple of weeks in your conventional (not frost free) freezer. Use a thermometer to set your fridge up, not the useless dial on the thermostat. If any of you have fridges older than 12 to 15 years, get rid of them. Gaskets leak, thermostats of the old type get inaccurate, fibreglass insulation shifts in the cabinet creating hot spots. Modern fridges are far superior on temperature control and energy use.

    There... more than you even wanted to know.

  13. #13
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    Well, it turns out to be a bit of a moot point.

    Our fridge (two years old, bottom-drawer freezer, near the top of the GE line) ran at it's highest setting all night, and this morning the thermometer read 5 degrees. If it can't easily achieve zero degrees, I'm not going to burn it up trying.

    Besides, I like our electric bills just as they are too. 15 degrees will have to do. Ice cream gets too hard at zero degrees anyway.

    Thanks guys.

  14. #14
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    This is interesting. I bought a 4.4cf dorm-type refrigerator/freezer because it was the biggest thing I could find that was NOT frost-free. I thought any temp cold enough to keep the ice cream hard was good enough, but I'll turn it all the way down after reading this. Went from running the old fridge about 12 hours a day (it seemed) to this one which runs 2 at the most.

    IMHO frost-free refrigerators are the biggest waster of electricity on the planet. If the govt. can mandate 1.6 gallons for toilets, why not mandate that nonfrost-free refrigerators at least be made available? If they did away with frost-free refrigerators we probably wouldn't need another new power plant for 30 years. Are Americans really too lazy or stupid to spend an hour every 3 months defrosting the fridge? It's ridiculous.

    [ 01-17-2005, 10:14 AM: Message edited by: Victor ]

  15. #15
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    -10 C. is recommended.

  16. #16
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    Originally posted by Victor:
    ...If they did away with frost-free refrigerators we probably wouldn't need another new power plant for 30 years. Are Americans really too lazy or stupid to spend an hour every 3 months defrosting the fridge? It's ridiculous.
    The average frost free household fridge costs well under $100 a year to operate. Since there is so little interest in manual defrost models, development has been focused on frost free. The better frost free models now consume no more electricity than manual defrost of similar size. Even with an older model, the potential savings is almost nothing.

  17. #17
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    fish - 20deg C

    meat - 18deg C

    shipboard standard, AFAIK.

  18. #18
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    I depends on how long you are going to keep the food.

    You can keep ice cream in the refrigerator section is you eat it within a couple hours.

  19. #19
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    Storage, 0 F or -18 C. The "sharp freeze" compartment should go down to -20 .. -40 F or -29 .. -40 C.

  20. #20
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    You're comparing new units with old units, High. If they can improve the efficiency of frost-free fridges so much, how much could they improve the efficiency of non-frost-free ones? They've gotta use less power no matter how you cut it.

    $100 a year is $8.35 a month. My electricity costs about 10.5c/kh, so 8.35 is about 80 hours a month. That's about 2.5 hours a day or so.

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