Poorly Insulated fridge / freezer?

 Hi All,

I hope this is a good place to ask the question. If not....

Due to an upcoming solar installation, I have recently started
changing / monitoring things in my house that consume electricity.

Quick details:
Fridge is a double door LG something or other. Rated A.

On Saturday I was doing some work on lights and had the power off for
about 4 hours.
When I turned it back on, I had a look at the fridge's display. The
freezer was -5 and the fridge was 5.
After about 20-30 minutes, the fridge was still 5 and the freezer was
-24. These are the settings they are supposed to be on.

My question is why would the freezer loose (gain?) so much temperature
while the fridge does not. I accept the difference between temperature
differs of fridge and freezer but to drop by that much?

One thing that could explain it is the fridge was mostly full while
the freezer was mostly empty. The lack of thermal mass in the freezer
causes it to warm up quicker? (Should I fill it with bricks? :) )

TIA

Cheers,
Crispin

  On Tue, 19 Aug 2008 03:21:28 -0700 (PDT), Crappy

 
Thanks Ken,

Does this occur only when there is a loss of power or does the
compressor turn on more often in an empty fridge?

Actually, there is a dim light turning on somewhere in my head. I seem
to recall about empty fridges being less efficient than full ones.

 wrote:


Yes, but that's mostly, maybe completely inconsequential.


With modern energy efficient refrigerators, I doubt that this is the case
anymore, at least, not enough to matter.  Easy enough to find out with a $20
Kill-A-Watt.

If you're wanting to store "coolth" for during a power outage, bricks are very
poor choice.  They only store cool in the form of specific heat and not the
heat of fusion which for any substance, is vastly higher.  With water it is
over 60 times higher if memory serves.  Second, bricks are poor conductors of
heat.

One of the best storage mediums is brine.  A saturates solution (all that will
dissolve) of salt freezes and thaws at about -4 deg F.  That means that the
freezer compartment, if filled with containers of brine, would remain at
nearly -4 deg until most of the brine melted.

Antifreeze is even better.  Propylene glycol, the red RV antifreeze is
non-toxic (indeed, it is a food ingredient) and in a 60% concentration with
water freezes at -60 deg F.  Here is a table of concentrations vs freezing
point:

http://www.engineeringtoolbox.com/propylene-glycol-d_363.html

In general, you'd want your cold storage medium to freeze (and melt) at nearly
the coldest temperature that your freezer normally operates at.  I say
"nearly" because you'd not want it to be thawing during normal operation.

Vacuum-sealed (without the vacuum, of course) bags of the solution are the
most convenient form that I've found.  I make my own version of "blue ice"
that way.  Mine is "pink ice" because I use RV antifreeze. I use them to keep
my insulin and drinks cool when I'm traveling.  Unlike water ice, they'll keep
my drinks slushy cold like I like 'em.

If you don't think that you'll be using your freezer for anything else then
plastic quart freezer containers of brine or antifreeze will do the job. Leave
a little air circulating space between them.  They're less convenient to take
in and out than vacuum-sealed bags which is why I recommend them for fixed
use.

For vacuum-sealing, I use the other brand that Wallyworld sells besides
Seal-a-meal.  The bag material is much tougher and a bit more expensive.
Sorry, I can't recall the name at the moment.

Once you get your freezer full of frozen antifreeze or brine, I suggest doing
a test before you rely in it.  The test is simple and involves only unplugging
the refrigerator and monitoring the refrigerator temperature with an
indoor-outdoor remote bulb thermometer.

The reason you want to do this is that some refrigerator designs rely on a fan
to circulate cold air between the refrigerator and freezer while others use
natural circulation.  The freezer temperature control is the thermostat while
the refrigerator temperature control is typically a damper.

If your refrigerator compartment doesn't stay cold then you may have to make
plans to run the fan - perhaps one of the little 100 watt inverters and a
battery.  During the test and during power outages, make sure the refrigerator
temperature control is turned to full cold.  That will fully open the damper.

John


--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com  <-- best little blog on the net!
Tellico Plains, Occupied TN
No one can be right all of the time but I'm getting close.

 
Thanks John,

I will try the brine and antifreeze option. My fridge / freezer does
use a fan to circulate the air withing each compartment but not sure
about between them.

I want to get the down to use as little power as possible. Hopefully
this _might_ make a difference...

I have also changed the temperature from -24 to -10. I figure so long
as the food is frozen, there is no state of "it's more frozen". I
might be wrong though.