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How long does a freezer stay frozen when the power goes out?

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Re: How long does a freezer stay frozen when the power goes out?

#81

Post by gruez »

technofiend wrote: post #57
rsync wrote: post #9

Related ... the last time I was in the market for a chest freezer (a "deep freeze") I wanted one that showed a log of temperature over time ... This, essentially, does not exist. It appears that there are laboratory freezers that support this (very simple) feature, but they are relatively small and very expensive . A better way to go is an electricity monitor on the plug, where you track electrical power over time an…

My wife was convinced the refrigerator was failing so I bought a few sensor tags from wirelesstag.net [1] just to be sure. You can certainly build your own using off-the-shelf IOT devices, but for ~$35 you can have a device that senses temperature, humidity, light levels,and runs for several months off an easily replaced cr2032. Although to be fair you must buy a base sensor station for $39 along with the first tag.…

I looked at the product page for the wireless sensor and I saw this:

>No subscription fee of any kind for life; no monthly or annual fee to use cloud service and no cloud storage fee for data collected by sensor tags.

>High anonymity: only your account email address and tag manager IP address is collected

That sounds... slightly disturbing. It suggests the tags sends all the data to the manufacturer's server. That's bad from a privacy and reliability (eg. company goes bust in a few years) perspective.

Re: How long does a freezer stay frozen when the power goes out?

#82

Post by pwg »

Someone1234 wrote: post #10
at_a_remove wrote: post #8

Personally, I throw blocks of dry ice in there as soon as the power has been out a few hours, just in case. Beats regular ice all the way.

How do you safely handle dry ice? I'm legitimately asking, I know retailers sell it with big warning labels but I wouldn't know how to transport it, move it, and similar.

> How do you safely handle dry ice?

Heavy leather work gloves have worked well for me the few times I've needed to load some dry ice into a freezer due to a power cut.

Re: How long does a freezer stay frozen when the power goes out?

#83

Post by walrus01 »

morninglight wrote: post #64

The location of the freezer or refrigerator is critical. If you live in a house that has a typical unfinished basement, don't overlook the advantage it offers. With one simple change, you can noticeably lower your electric bill, reduce your carbon footprint, gain extra kitchen space and improve your health. Just move your refrigerator to the basement. Since the basement is normally cooler than the upstairs, the refri…

As an additional benefit, since any fridge or freezer generates waste heat on its 'warm' side (the room itself), the additional heat from the freezer will rise from the basement into the rest of the house. As compared to if you had a freezer on the 3rd floor of a tall/narrow town house, all that the heat would do is rise towards the ceiling and attic.

I would not advocate for moving a fridge to the basement just because of the hassle and back and forth trips involved. But if I had a dedicated top-opening chest freezer, sure.

Re: How long does a freezer stay frozen when the power goes out?

#84

Post by walrus01 »

stblack wrote: post #61

I bought and filled a chest freezer in pandemic preparations. Cost of the chest freezer: CAD 1,000 Cost to completely fill the freezer with good food: CAD 2,700 Given that, during a pandemic or a winter storm in Canada, a power failure can be a prolonged event... Cost of a good gas powered generator to keep the freezer viable beyond a day: CAD 1,000. This article seems to validate the generator purchase.

If society and food supply chains had actually broken down due to a massive pandemic (imagine ebola with a 30% fatality rate tearing through a population of 350+ million in the USA and Canada) you would have been much better served by a stockpile of rice, beans, canned food, multivitamins and other true disaster supplies.

Re: How long does a freezer stay frozen when the power goes out?

#85

Post by function_seven »

01100011 wrote: post #58
at_a_remove wrote: post #53

Earlier quoted context omitted.

I've handled it for decades. First thing you do when you get your slab is that you wrap it in two towels, then you fold down the loose edges and pop that in a cooler. Towels towels towels, that's my go-to. You can handle dry ice with your bare hands -- I have scores of times -- the trick is that contact with pressure (squeezing or weight) is what is going to give you frostbite. Otherwise, I have swiftly moved two pou…

One note: if it behaves like dry ice in a cooler does, it can carbonate many of your food items. I've used dry ice on camping trips and ended up with carbonated fruit.

I can't tell if this is a warning, or a cool discovery.

I feel like carbonated fruit would be a treat, but I suspect I might be wrong?

Re: How long does a freezer stay frozen when the power goes out?

#86

Post by refurb »

gruez wrote: post #78
refurb wrote: post #60

Earlier quoted context omitted.

Specific heat capacity: --- Water (liquid) - 4.80 J/g.K Water (solid) - 2.108 J/g.K (transition 334 J/g) Brine (liquid, 300g/L) - 2.48 J/g.K --- So 1 gram of water (s) going from -18C to 0C (liquid) is 373 J. 1 gram of brine (l) going from -18C to 0C is 44.64 J. Seems like ice is a better choice? The phase transition requires a huge amount of energy. Brine is 70% more dense than water, so if you do it by volume, one…

>Seems like ice is a better choice? The phase transition requires a huge amount of energy. Why are you excluding the phase transition energy of the brine? Presumably you can calibrate the salinity so it freezes at around say... -15C, and set your freezer to -18C. That way it's absorbing heat more heat when it's colder, which is helpful if you want to keep your food frozen. The latent heat of water isn't of use to you…

Because OP mentioned saturated brine and a freezing point of -18C.

Re: How long does a freezer stay frozen when the power goes out?

#87

Post by function_seven »

at_a_remove wrote: post #80
01100011 wrote: post #58

Earlier quoted context omitted.

One note: if it behaves like dry ice in a cooler does, it can carbonate many of your food items. I've used dry ice on camping trips and ended up with carbonated fruit.

I have used this, in a more dangerous fashion, to recarbonate flat soda.

Drop a few pebbles of dry ice into a 2-liter bottle, cap, and monitor for plastic stretching sounds?

Re: How long does a freezer stay frozen when the power goes out?

#88

Post by rsync »

kevindong wrote: post #20
rsync wrote: post #9

Related ... the last time I was in the market for a chest freezer (a "deep freeze") I wanted one that showed a log of temperature over time ... This, essentially, does not exist. It appears that there are laboratory freezers that support this (very simple) feature, but they are relatively small and very expensive . A better way to go is an electricity monitor on the plug, where you track electrical power over time an…

Such data might be interesting to look at, but as long as the freezer does its job (aka keep everything stored within it fully frozen), what's the point in having that data?

"... what's the point in having that data?"

In normal, day to day life, I think it would have little value.

The use-case I am envisioning here is: you have a high value store of frozen items (meat, etc.) and you leave your home for 20 or 30 days ...

When you get back, the freezer is running nicely and everything is frozen and things look great - but what if there were a 3 or 4 or 5 day power outage in the middle of your trip that thawed things out just enough to spoil ?

Or what if there were one or more power outages (or brownouts) that you were aware of that were not, in fact, long enough to ruin your stored food ... but how would you be sure ?

If you had a time view of freezer temps you could make those determinations easily.

Re: How long does a freezer stay frozen when the power goes out?

#89

Post by aaron695 »

dantillberg wrote: post #49
aaron695 wrote: post #46

Earlier quoted context omitted.

You'd be better off having lidded containers with no water. Since it stops the air loss every time it's opened. But you don't lose the energy when you take them out. Water is ~ 1000 times heaver than air so for a fridge, removing the water is the same as letting out air 1000 times. Freezer is worse because there is also the phase change in the water. But having ice is useful.

It depends what you're optimizing for. If you're primarily interested in resilience to power outages, then maybe you are OK with the wasted energy used to freeze/re-freeze the extra water.

Yes I'm wrong.

You would have a larger thermal mass but the same surface area so it should keep for longer.

Re: How long does a freezer stay frozen when the power goes out?

#90

Post by dillonmckay »

asdfasgasdgasdg wrote: post #6
dillonmckay wrote: post #4

Does it not depend on what is in the freezer? Like, if it is half-filled with icepacks versus frozen beef?

The article addresses thermal mass, although not into the level of detail of X% ice packs and Y% food.

I keep a certain amount of icepacks in the freezer, in case the power goes put, but also because the thermostat seems to swing a bit.
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