Freezers

eschulze

Hi Folks,
I've been looking for the best freezer option for my medium-sized off-grid system and I have two specific questions that I'm hoping someone has actual experience with.
First, has anyone tried running one of the DC direct freezers in an unheated (below freezing) environment? Either the Sundanzer or the Steca, or some other option I'm unaware of. I've read some speculation that this will not work with the Sundanzer, and the Steca product sheet lists +10C as the lower end of the recommended ambient operating temperature. But has anyone actually tried using them this way?
Second, has anyone had any luck getting an AC freezer to work with an inverter in search mode, or does the inverter have to run 24/7? I assume that has to do with how the thermostat works and expect it probably needs continuous power, but I don't know for sure.
Thanks.

BB.

Re: Freezers

From what I know, the frost free models are the ones that work better with search mode turned off (24x7 inverter operation).

These guys usually have a mechanical or electronic timer that runs a defrost cycle every ~12 hours. And with the electronic timer models, many (some/many/all?) will usually start a defrost cycle when the AC power is turned on.

The manual defrost freezers (with mechanical thermostats) usually will work just fine with search mode turned on.

-Bill

vtmaps

Re: Freezers

eschulze wrote: »

First, has anyone tried running one of the DC direct freezers in an unheated (below freezing) environment? Either the Sundanzer or the Steca, or some other option I'm unaware of. I've read some speculation that this will not work with the Sundanzer, and the Steca product sheet lists +10C as the lower end of the recommended ambient operating temperature. But has anyone actually tried using them this way?

Welcome to the forum,

I have a Sundanzer. They do not work reliably when operated near their ambient temperature. This is because the thermostat is NOT in the food compartment. I think it is in the freon return from the evaporating plate. When ambient temp is too low, the thermostat may think the food cabinet is cooler than it actually is.

There may be other reasons... speculation: perhaps the lubrication of the motor or compressor is compromised at near freezing temperatures.

--vtMaps

waynefromnscanada

Re: Freezers

I've had a 120 volt freezer operating in an unheated outbuilding for probably 10 years with no problems. Temps there drop at times to minus 25C and no probs. Worked fine on search mode inverter. Hardly ever runs in Winter as not much heat to leak in through it's insulation. Monitor internal temp and it stays pretty much steady, year round.

BB.

Re: Freezers

With "standard" (i.e., cheap) refrigerator/freezer combo units--The thermostat controls the refrigerator temperature and the freezer is just a dump for the cold air when the refrigerator thermostat calls for cooling.

When operated in a cold envrionment, the refrigerator never calls for "cooling", and the freezer section runs "warm".

-Bill

DanS26

Re: Freezers

I've always wondered how soft drink machines can sit out in below zero weather for weeks without their contents freezing. Heaters or some reverse cooling method?

BB.

Re: Freezers

Search engines have changed the world:

https://in.answers.yahoo.com/question/index?qid=20080125122256AAT2JW7

• Mike the vending guy answered 6 years ago

Well depending on the manufacturer of the machine and the company that bought it, they can have a heater. It is an extra option and many companies don't buy that option because so many machines are placed indoors these days. Although I am sure that in the colder states that the big boys, Coke and Pepsi have heaters in their machines and there is a computerized thermostat inside that will turn off the refrigeration system and turn on the heating system.

It sounds like some do not have the heaters and may use the lighting/evaporator fan to make some warmth inside. In cold climates the distributor may install a 65 watt lamp (turn on during winter).

And some guys have pulled frozen/split cans from machines (7-up appears to freeze first).

-Bill

eschulze

Re: Freezers

Thanks for the manual vs. auto defrost info, makes sense. Steca anyone?

nobody928

Re: Freezers

I think sundanzers are over priced. I use a regular deep freeze chest freezer with manual defrost and it works good. Im sure they can do well outside as many of my neighbors use them outdoors.

mike95490

Re: Freezers

I've just ordered a Kenmore 20cf upright, manual defrost freezer, and in winter (it will live out in the garage) I plan to place it on a timer, and only allow it to run 9am -3pm Summer, I've got plenty of power for it. After I have it, I may try to "wrap" it with some more insulation - if it does not have the cooling coils on the outer cabinet walls.

inetdog

Re: Freezers

mike95490 wrote: »

... if it does not have the cooling coils on the outer cabinet walls.

We all know what you meant Mike, but I will still point out that the problem is the condenser coils, which arguably are not cooling coils (cooling the interior) but heat rejection coils, sort of cooling the whole box, but producing hot spots which need cooling air available.

samppa

Re: Freezers

mike95490 wrote: »

I've just ordered a Kenmore 20cf upright, manual defrost freezer, and in winter (it will live out in the garage) I plan to place it on a timer, and only allow it to run 9am -3pm Summer, I've got plenty of power for it. After I have it, I may try to "wrap" it with some more insulation - if it does not have the cooling coils on the outer cabinet walls.

This. I've been thinking if a freezer could work like this: run it e.g. from 9am to 4 pm (or however to sun hours go). Maybe put some extra polyurethane insulation around it. If you can get it to -20C during the day, it would stay pretty cold until morning. You'd have a nicely cold drinks cooler and it wouldn't drain the batteries as much.. what's the idea sound like?

vtmaps

Re: Freezers

samppa wrote: »

This. I've been thinking if a freezer could work like this: run it e.g. from 9am to 4 pm (or however to sun hours go). Maybe put some extra polyurethane insulation around it. If you can get it to -20C during the day, it would stay pretty cold until morning. You'd have a nicely cold drinks cooler and it wouldn't drain the batteries as much.. what's the idea sound like?

Read about holding plates and eutectic solutions:
http://forum.solar-electric.com/showthread.php?4860
http://forum.solar-electric.com/showthread.php?p=175235#post175235

--vtMaps

Dave Angelini

Re: Freezers

Direct excellent experience with the the Stecca at 15F Ambient room temperature at 2 homes up in the Sierra. The Stecca 24V is an amazing product! No Frost for 2 years and sips DC less than anything out there. Works very well also at 90F + ambient room. We use to get them from Sunwize Direct but now that they are merging with Soligent so, who knows? I did a review on the forum here you can search. Good Luck!

BB.

Re: Freezers

Make sure your temperatures do not rise above much above 0F -- Especially if you store food for many months at a time:

Question - Best Freezer Temperature

Also monitor the temperature swings... Wide temperature swings can cause "freezer burn" ("warm" food and very cold air around it will "freezer dry" the food--pull the moisture out of the food and form ice around it).

And watch adding insulation to the outside of the freezer--Besides the fact that many freezers put their condenser coils around the outside of the cabinet sheet metal--Years ago we had problems with condensation of water and ice on the outside of the freezer, and rusting the cabinet.

-Bill

waynefromnscanada

Re: Freezers

BB. wrote: »

Make sure your temperatures do not rise above much above 0F -- Especially if you store food for many months at a time:

Question - Best Freezer Temperature

Also monitor the temperature swings... Wide temperature swings can cause "freezer burn" ("warm" food and very cold air around it will "freezer dry" the food--pull the moisture out of the food and form ice around it).

And watch adding insulation to the outside of the freezer--Besides the fact that many freezers put their condenser coils around the outside of the cabinet sheet metal--Years ago we had problems with condensation of water and ice on the outside of the freezer, and rusting the cabinet.

-Bill

Excellent points Bill! I at first ran my freezer only during the day, but ran into these problems, and found I was just as far ahead letting it run as needed.
Beware of temps above 0F (Minus 18C) if storing food beyond a relatively short time.

peakbagger

Re: Freezers

I bought a small (8 cubic foot) chest freezer from sears two years ago. It has coils buried under the sheetmetal on the back of the unit. I glued 2" Isoboard foam I had hanging around and made a rabbet joint on the side walls that stick up past the top. I then made a foam plug with a matching rabbet joint that sits on the top and mates with the side rabbets. I did not insulate the back. It is quite noticeable when I remove the top plug that the top cover is colder than room temp. I don't have any condensation issues until later summer when the humidity is high in the house. I have had to wipe it off once or twice but have not seen any mold. If I glued the foam plug to the top cover I expect it would solve the occasional condensation issues but would require me to pull it father away from the wall to allow the top to open up. Looking at similar size Sundanzer it looks like they use a standard outer case size and have custom interior liner which also incorporates a top cover with angles on the side that mate up with the side walls.

zoneblue

Re: Freezers

Interestingly Danfoss now make a compressor with zero start surge, designed to be powered off PV direct "BD Solar compressor". Might have application somewhere but i dont know whether or which products youll see that model installed in.

http://www.danfoss.com/Products/Categories/Group/ra/Compressors/Direct-Current-Compressors/b44e7573-473b-4dba-90c2-431ffccf0b9c.html

westbranch

Re: Freezers

looks like the max size is ~ 200 L for fridge size see section 2

http://www.ra.danfoss.com/TechnicalInfo/Literature/Manuals/06/application_guideline_bd_solar_09-2005_pa100a202.pdf

mike95490

Re: Freezers

mike95490 wrote: »

I've just ordered a Kenmore 20cf upright, manual defrost freezer, and in winter (it will live out in the garage) I plan to place it on a timer, and only allow it to run 9am -3pm Summer, I've got plenty of power for it. After I have it, I may try to "wrap" it with some more insulation - if it does not have the cooling coils on the outer cabinet walls.

Bummer, the heat dump coils ARE under the cabinet outer skin, the whole outside heats up as the inside cools off. No way to add any additional insulation on the beast.
But the upside is there is no fan to suck up cat hair and clog the works.

Desert Rat

Re: Freezers

I have a run-of-the-mill Sears 8 cu. ft. chest freezer, and I have measured daily draw at 1300 watt hours in summer 100+ temps in an un-air conditioned shop. Assuming you already have a decent size system, you can buy a freezer like this AND the additional solar panels to run it for less money than a DC freezer. That's here in the sunny southwest, YMMV.