Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

woodgears.ca

Post reply on HN
Print view View original

71–80 of 384 posts

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

#71

Post by ghaff »

baggy_trough wrote: post #66
ghaff wrote: post #13

Earlier quoted context omitted.

I actually went through this last week. The problem is that, if the power goes out (presumably without advance warning), a bunch of triage to basically turn your freezer into a cooler for critical items is going to cost a bunch of the stored cold air. I'd probably go instead, if you have a cooler, with buying a few bags of ice if you can and quickly pulling out high value/especially perishable items and putting them…

You don't have to be so quick about it. The heat capacity from warm air coming inside is dwarfed by that of the frozen solids and especially their latent heat absorbed during the melting process.

You're right. If things had gone on much longer, I'd probably at least have tossed a few bags of ice in my main freeze. (Probably better than pulling stuff out and so forth.)

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

#72

Post by nickpeterson »

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?

Keep in mind that while They’re not overly expensive, it’s pretty easy to pack a few thousand dollars worth of food in a chest freezer. Might be worth testing it...

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

#73

Post by [deleted] »

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.…

[deleted]

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

#74

Post by gruez »

jhallenworld wrote: post #69

Here's what I've learned about refrigerators recently. My fridge is failing in a revealing way. It has an automatic defrost unit- this means that it heats the evaporator coils in the freezer every so often (I think it's once every 36 hours) to melt the frost off of them, producing the same condensation you normally get from an A/C. So where does this water go? Well there is a hose from the freezer to a pan underneath…

> This is where the planned obsolescence comes into play. I'm convinced that the manufactures make this metal out of steal with just the tiniest amount of galvanization so that it will eventually rot out.

One thing I never got about "planned obsolescence" as some sort of way to get more recurring revenue is how it works with competitors. If you're the only game in town then it makes perfect sense, but if your appliance died an early death, are you really going to buy from the same manufacturer? What if another manufacturer doesn't do the same thing and their appliance lasts longer? Wouldn't you lose market share? For it to work you'd need some sort of conspiracy with all the other competitors so everyone cuts quality in unison, which we haven't seen a lot of evidence of. The only one that comes to mind is the lightbulb one.

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

#75

Post by cbsks »

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…

That’s a clever idea!

I’m not sure how practical it is, however. The first problem that popped into my mind was that the stove would often be unattended while I ran downstairs to grab something I forgot from the fridge.

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

#76

Post by [deleted] »

contingencies wrote: post #59

It depends on the thermal mass of the contents, the effectiveness of the insulation, and the external ambient environmental temperature. In real world use, it also generally depends on (1) how frequently and for how long you open it, and (2) whether it's top-loading (efficient) versus front-loading (inefficient). Source: My venture custom designed and built a refrigeration circuit with autonomous electronic managemen…

[deleted]

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

#77

Post by vageli »

cbsks wrote: post #75
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…

That’s a clever idea! I’m not sure how practical it is, however. The first problem that popped into my mind was that the stove would often be unattended while I ran downstairs to grab something I forgot from the fridge.

> That’s a clever idea!

> I’m not sure how practical it is, however. The first problem that popped into my mind was that the stove would often be unattended while I ran downstairs to grab something I forgot from the fridge.

I often leave the stove unattended whilst I check the grill outside. So long as it's less than a few minutes (and you have a fire extinguisher on hand in the kitchen—as one always should), there shouldn't be a problem in most circumstances.

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

#78

Post by gruez »

refurb wrote: post #60
jacknews wrote: post #11

You want the contents to remain BELOW 0C, not hovering at 0C while everything melts. You can do this by adding some salt-water bottles, which have a lower melting point, and will therefore absorb a lot of heat (heat of fusion) well below 0C. Eg add 250g salt/liter gives melting point of -18C. Of course you waste some space on useless salt water vs potable - maybe there are better alternatives, eg fruit juice? Milk? H…

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 if all your meat is already thawed.

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

#80

Post by at_a_remove »

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 have used this, in a more dangerous fashion, to recarbonate flat soda.
Post reply on HN