Freezer temp - what do you set it at?

[Insequent]

I am about to start an extended cruise. While I can go regularly into marina's for provisions I like to be able to anchor out amongst the islands or in somewhat remote inlets. Keeping fresh fruit and veg for extended periods is kinda OK, but often these perishables don't have a lot of shelf life left by the time you buy them in the supermarket. So I usually cook a lot of meals at home, freeze them and store on board until needed.

I have plenty of freezer capacity with 2 x Waeco CF 110, plus the freezer compartment of the Norcold in the galley. The newer Waeco allows me to set a 'holding temp', but I wonder what value to choose? I see that for household freezers the recommendation is below 0°F (-18°C). The reason is that food keeps far better. Thats fine, except that the Waeco uses a lot more energy with decreasing temps. I have measured Ah draws at -5°C and at -10°C. The newer Waeco will go lower, but I've not measured the draw at lower temps and I don't think -18°C would be a practical target on the boat. Holding at -10° uses double the Ah per day compared to holding at -5°C. So, for extended anchoring out I would prefer to run at -5°C or thereabouts.

Two questions: First, what temp do you set your freezer at on board? Second, if the food is only being kept for a month or two, are any significant health issues likely from food deterioration?

 

[tiltrider1]

I have a sub zero freezer on the boat that does not have a frost free setting. Meat and fish will keep fine for well over a year. Frost free devices shorten the life of frozen objects way more than being at -5C. So being -5C with no frost free cycles, things should last 6 to 9 months.

 

[BruceK]

Brian, some reading suggests-18C is "safe" for a range of reasons, the question is how much "lower" (?higher) you could safely set it.
Part of the -18C setting is the extended period it holds food safely frozen. If the period sought is shorter, maybe you could get way with less.My eutectic system takes the freezer to -20C and the fridge +2C, then of course it gradually warms until the compressor kicks in again. The temp at which that happens could be instructive for your purpose, especially as you have virtual constancy with a cycling freezer.
-5C does not seem cold enough if -18 is the norm. Maybe -10-12C is ok.
Or you could experiment with different temps to see when you get sick.

 

[Insequent]

Bruce, I am not inclined to test by getting sick!

Most likely the food quality declines at the warmer temps. And although I usually thaw before re-heating, then nuke it before eating. Microwaves get rid of some bacteria if you make the food quite hot but then allow to cool enough to eat. So I doubt I'll get sick anyway.

I suspect many people don't actually know what temp their freezer is running at anyway. I'm guessing you don't know what temp your eutectic system switches on again?

 

[BruceK]

I have temp gauges on both fridge and freezer,I buy them on ebay, the simple probe on a wire type. I had a "genuine" wireless Engel, but most of the time the sender and display were not on speaking terms.
A quick search failed to find a "cut in "temp. True, I don`t know my "cut ins",and wouldn`t know if fridge or freezer was calling for "cut in",as they share the compressor.
My vague recall is reading, somewhere, maybe in an instruction manual for a previous home freezer, that for frozen long term -18,for less extended periods -12. My home 2 door fridge freezer runs at +3 fridge/-18 freezer.

 

[auskiwi]

If my memory serves me right, Ice Cream freezes at -18C, that's what I use for the freezer, it keeps the fridge at around +2, using a eutectic system. Once down to temp only need 2-3 hrs running a day, providing you don't open the lid.

 

[Bendit]

In my experience, it very much depends on where the probe is. Indicated temps will be lower if the probe is at the bottom of the box.

Since I had the freezer rebuilt, it's much more efficient and I've settled on a compromise of set point at -12 deg C and differential of 5 deg C so it cuts in at -7 deg C. The probe is at the top of the box and I reckon this is pretty much the same as - 18 deg C, which I used to run with the probe at the bottom.

 

[AusCan]

I agree with Bendit, the placement of the probe makes a big difference. Don't rely on the digital readout. Also the temperature varies substantially within most freezers without super-good insulation.




Besides the temperature, there are many variables which will affect the storage life of food in the freezer. One of the biggest is how well, and how long was the food was stored before it was frozen. I'd worry more about that rather than whether the freezer is at -18 or -10.


Things like whole chickens, roasts, steaks will store much longer than processed meat like bacon, sausages, and ground beef.


Buy it as fresh as possible, freeze it well at home, then transfer it to the boat freezer without delay, and you can get away with a slightly warmer freezer temperature.

 

[Simi 60]

-20 on freezer and +3 on the fridge for us.
3 monthly bulk shop for meat, haven't got sick yet.

 

[HeadMistress]

Fwiw, I've always kept my freezers at home at -2 F and my fridges at 38 F. I keep thermometers in each one instead of relying on any gauges in them. I have a Foodsaver which lets me buy chicken, fish and meats in quantity, separate them into 1 and 2 serving vacuum sealed packages...I also make stew, chili, pasta sauce and soups and freeze those in vacuum sealed 2 serving containers. I've found things that have been in the freezer in my garage a year or even longer with -0- deterioration (the all time record was a rack of lamb I found last summer that I'd frozen in 2014...no deterioration).

Because bacteria become dormant at 40 F, some perishables can last 2-3 weeks in a 38 F fridge...it depends on how fresh they were when they went in. My Freshsaver mason jar sealer (Foodsaver gadget) lets me keep almost anything for at least 3 weeks in the fridge.

That's what works for me...your mileage may vary.

Peggie

 

[Insequent]

Thanks for replies folks. I think I'll err on the side of caution and run as cold as practical. Which means whatever temp the 2000 W of solar panels allows me to do without needing to raise anchor and move every day.

I'll run the newer Waeco at -10°C, or maybe a bit lower, and use it for the longer term storage. Good point about using a probe to test rather than just assume display is showing what the temp in middle of the unit is.

The older Waeco is running, but cutting out at present. I was not using it last year, so usual story for stuff on a boat. I found a dry joint (power connector on a circuit board) and am replacing the plug on the power cord also as it is getting warm. A poor internal connection it would seem. I'll test out temp wise once wiring is all sorted, but use stuff from it first anyway. It has a slightly warped lid which obviously impacts performance, but I have ordered a new lid as well. I suspect it will operate somewhere between -5 and -10°C, but maybe the new lid will allow it to run colder - here's hoping!

 

[BruceK]

I agree with Bendit, the placement of the probe makes a big difference. Don't rely on the digital readout...

Sounds like a prostate check.
Brian, Anaconda,a Sydney outdoors/camping /boating shop, has a "Member" price of $699 for Waeco 50L,quite cheap. But, they may not be in Qld. Membership is free.

 

[Insequent]

Bruce. Other places such as Tentworld have the same 'deal'. No doubt Dometic is the one doing the discounting!

I'll keep the old unit running as long as I can. I have some spares for it, although not for everything that could break. I am unlikely to replace it. I rarely use the old Waeco, and have an Engel in the pilothouse that only runs when extra drinks capacity is needed. It could run as a freezer if I ever take a boat load of people into a remote area. But I don't plan on doing that anytime soon!

 

[BruceK]

Fwiw, I've always kept my freezers at home at -2 F and my fridges at 38 F. I keep thermometers in each one instead of relying on any gauges in them....
That's what works for me...your mileage may vary.
Peggie

Your fridge/freezer +38F/-2F = about +3C and -18C, well accepted for home.
Today the boat was +2.5C/-20C,I think the compressor ran not long before I got there.
My thermometers,from Ebay, have a display unit using AAA battery(I avoid the button type), a thin wire introduced via the door, probe at the end,and plastic holder for the probe. An external display saves opening the cabinet to check temp,I doubt the wire bothers the seal much,one used a flat wire which seemed a good idea.

 

[caltexflanc]

Also in the 0 F club here.

Peggy made an important comment: a vacuum sealer makes a very big difference in the longevity and more important, quality of frozen foods. It was one of the best things we got for the boat, and we moved off the boat, we took it with us. We've cooked items lost in the back of the freezer that were almost a year old and they were excellent. Ann date stamps each piece with a Sharpie.

How often you open the thing each day affects power consumption as much as anything (save very poor insulation). We had a separate ice maker, so we'd open the freezer maybe once a day. Our preference was to spend almost all of our time on moorings or at anchor. There was just two of us on board full time, but we also like to cook and entertain so having a lot of refrigeration capacity was good. We could go a long time without restocking the freezer, stocking up when near a Costco or somewhere like Penn Dutch. Meats and fish not to be eaten that week were immediately sealed and frozen.

 

[Simi 60]

Thanks for replies folks. I think I'll err on the side of caution and run as cold as practical. Which means whatever temp the 2000 W of solar panels allows me to do without needing to raise anchor and move every day.
!

We run a 2 door 500 litre fridge freeze, a 100 litre freezer, and 2 x120 litre bar fridges ALL 240v.
Our 2250 W of solar runs that easily and batts are at 100% by midday most days.
In summer it even has the 240v HWS done.

You should have no issues with 12v and 2000 W