# Ideal fridge temperature accounting for temperature spikes

I've read the question on the ideal fridge temperature, but am asking a more involved question about a baseline temperature and temperature spikes. How will a few hours each day at 10 C effect the contents of the fridge? What about two smaller spikes to 7 C?

Background: I live in a small studio. The fridge makes noise. I'd like it to be quiet at night. If I can do so without frequent food spoilage, I'll get a timer and turn the fridge off from 2300 to 0800. If this is a bit too much time without cooling, I plan to turn it off while I fall asleep (2300 to 0200), turn it back on (0200 to 0400), and then have it be quiet in the mornings again (0400 to 0800).

I've put some temperature loggers in the fridge and unplugged it manually during the 2300 to 0800 time. The graph is attached below. The mean temperature is 3 to 5 C, rising to 10 C.

The 2nd day was 'bad' data: I added a few gallons of water to increase the thermal capacity of the fridge (temp spike), but added them too late in the evening. The water did not cool to 4 C, and when I unplugged it the temperature shot back up. The first day, with an almost empty fridge, is a worst-case scenario. When the fridge is full I expect the max T at 0800 to be 8 or 9 C, not 10 C. I am collecting that data now and will update the post in a few days when I've checked the variability.

If 6-8 C for a few hours, then 8 to 10 C for a few more, then a quick return to 3 C is bad for the food (mostly OJ, soy milk, cheese, and some veggies), then I'll cool it in the middle of the night when I'm in a deep sleep.

So... to the question: How important is a 4 C fridge? Is a few hours per day up to 10 C bad? What about up to 7 C? Any other suggestions how to quiet the studio as I try to sleep?

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I know this isn't the point of your question, but if you post more data, it'd be cool if you could use a thinner line so we can see the shape of the normal cycles too. – Jefromi Apr 19 '11 at 3:41
It depends also on the food in the fridge. Veggies that have 10°C is not so bad as raw meat that has 10°C. Also the age of all the food can play a role, I think. – Mien Apr 19 '11 at 8:29
If you really want to do this, you are probably going to have to take into account the thermal mass of the contents of your fridge, i.e., an emptier fridge will need to be initially cooled to a lower temperature to sustain sub-4C temperatures during the shutoff phase. This would require some sort of closed-loop controller that could sense the temperature gradient of the fridge and plan ahead for the desired shutoff times. This of course won't be as big a problem if you always have roughly the same contents in your fridge. – ESultanik Apr 20 '11 at 11:41
This is an awesome experiment. Maybe you could provide some detail on my question about fridge temperatures. cooking.stackexchange.com/questions/14174/… – yossarian Apr 20 '11 at 15:59
I'm surprised that the extra thermal mass wasn't more significant ... could you share last night's data, to see if it just needed more time to chill down? Also, do you have any readings on the room's temperature, so we know if that could be the cause of the elevated daytime temps on the later days? – Joe Apr 20 '11 at 18:47

Another possibility to consider would be adding ice blocks from a freezer during the times you want to not be running the compressor.

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This is roughly equivalent to a large thermal mass in the fridge. If 30% is a steel block, or several gallons of water, I won't need to manually do anything each night. – mankoff Apr 20 '11 at 15:03

I think that allowing the hardware to work as it is intended is likely in your best interest. Instead, I would refer your question to DIY.se (perhaps), to find out how to stop your fridge from being so loud.

So instead of possibly ruining a bunch of food, look into the pathology of the noise issue of the fridge. Some options I can think of are to:

• insulate the sound (i.e. unglamorously with a blanket)
• clean out the backside of any dust(-bunnies) etc
• verify that there are no air blockages (trapping the dissipating heat causes the compressor to work harder than it should)
• verify that the compressor is in good working order
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One thing I also wonder about is if the re-cooling period, with the compressor running constantly for an extended time, might potentially bad for it - if it's already working too hard, that might start pushing it hotter and wearing it out? – Jefromi Apr 19 '11 at 13:17
If you insulate the sound, be very sure you are not accidentally providing thermal insulation to the outside of the fridge or blocking fans too. You don't want it to overheat. – yossarian Apr 19 '11 at 13:39
your advice is based on the assumption that the "normal" operating noise of a working fridge won't trouble him. However, I know from experience that this noise, which is unnoticeable when moving around in the kitchen, can be very unpleasant at night, when the fridge is in the same room with you and not more than 3-4 meters from your bed. Especially if it is one of the small cheap models likely to be installed in an one-room-with-kitchen-corner flat. I just grew used to mine. But cleaning won't help with normal noise and insulating the compressor part is bad for heat dissipation. – rumtscho Apr 19 '11 at 13:42
@Rum I have a loud, annoying fridge that irritates me in the kitchen even with music on (belongs to landlord, who won't fix it). My answer is just saying that he should verify that there aren't problems exacerbating the fridge (via DIY) first before he goes through the trouble of doing [whatever]; especially if, as @Jef points out, un/plugging could damage the compressor and other hardware. It might also consume more energy (think of turning a television on and off). Also, please note that I included a step to assess heat dissipation / air blockages. – mfg Apr 19 '11 at 14:46
This is 'normal' noise. Fridge is, AFAIK, healthy and happy. Thanks for pointing out that the prolonged re-cooling in the AM could stress it. – mankoff Apr 20 '11 at 6:10

Have you considered earplugs? Or some other noise to mask it (like one of those nature sounds machines?)

Vegetables may go bad a little sooner (depends on the vegetable; some actually like it a little warmer). Cheese probably won't care. OJ is probably acidic enough to keep long enough to use it up. No idea about soy milk.

I would definitely not keep meat in there, since the ideal temperature for that is slightly below 0°C.

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I'm mostly vegetarian, so the meat isn't an issue. I've considered all sorts of things but prefer to not have earplugs or additional (even if white) noise. If I can just remove noise, and have on side effects other than a \$20 debit for a timer, that would be nicest. – mankoff Apr 20 '11 at 6:09