Pre-Cooling Refrigerators

[launderess]

Noticed when reading vintage owner's manuals many fridges called for starting up, setting thermostat anywhere from three to twelve hours before putting in food. Can understand wanting to cool down a hot box before addition of warm food to lessen strain on fridge, but nearly a day seems excessive.

Was this really necessary?

 

[neptunebob]

Might have been for food safety

The idea might have been for food to be cooled quickly enough to keep it out of the "danger zone" between 140 and 40 degrees, where bacteria growth can occur.

 

[rp2813]

That does seem excessive.  Presuming the new owner had cold items from the outmoded ice box to place into the new fridge, or purchased same at the market, those items would help to cool the interior rather than slow down the process.

 

IIRC, the literature with my mom's '75 Coldspot SxS did say that it could take 24 hours for the fridge to develop a cyclical rhythm based on a mid-range cold control setting, but there wasn't an advisory against placing contents in it during the process.   Whether that had anything to do with a fan circulating the cold air around, I don't know.  The one thing that almost all literature I've seen does state is that setting the cold control to the coldest option won't make the fridge cool down any faster. 

 

[launderess]

"The one thing that almost all literature I've seen does state is that setting the cold control to the coldest option won't make the fridge cool down any faster. "

No, it won't and that is one thing people just won't get through their thick heads. Same as those who walk into a home and turn AC down to 70F or even lower because they are "hot", and think it will cool things down faster.

Air conditioners, refrigerators, etc.. don't make cold air, but remove heat from it. Only thing turning down thermostat does is waste energy in making things colder than they should be.

Will give you with fridges it might take a bit of trail and error to find thermostat setting that keeps temps in proper range. This is why you stick a thermometer inside refrigerator and maybe freezer.

Older owners manuals suggest using milk and ice cream as test. After about 24 hours one was supposed to test how well a fridge cooled by having a drink of milk. If it was "cold enough", then fridge was at proper setting. However if too warm or cold adjustment was made to thermostat. Ice cream same; after waiting if thing was too soft freezer temp needed adjusting.

 

[rp2813]

I'm with you 100% on all of that, L!

 

[petek]

Interesting. I wonder if they were using a different type of insulation back then, were they fan equipped etc.

When it comes to refrigerated transport containers/trailers they were to be precooled for at least around 12 hours prior to being loaded with frozen goods.

I've lived for near 38 years with one of those people who turn the car a/c all the way down to cool and all the way up to heat in the winter,, there is no in between with them. When it's too cold in the car from the a/c it's turned off and when it's too hot in the winter he opens a window . Same with the house heating, thinks that turning it up to 80 is going to heat the house faster.

 

[warmsecondrinse]

"No, it won't and that is one thing people just won't get through their thick heads. Same as those who walk into a home and turn AC down to 70F or even lower because they are "hot", and think it will cool things down faster."

In partial defense I'd like to point out that I've rarely heard a person who does understand say to a person who doesn't.... "The heat/ac/refrigerator/etc. has no high,medium, or low. There is only on and off. That's it. Either it's on or it's off. The thermostat lets you set the temp at which the on/off happens. it's NOT a dimmer switch even though it looks like one. There's just on and off."

"I've lived for near 38 years with one of those people who turn the car a/c all the way down to cool and all the way up to heat in the winter,, there is no in between with them. When it's too cold in the car from the a/c it's turned off and when it's too hot in the winter he opens a window . Same with the house heating, thinks that turning it up to 80 is going to heat the house faster."

IMO, this is a bit different. It points toward something else entirely and this behaviour is just how it presents. Same with windshield wipers: There's high speed and off. They never use low or intermittent. Then they complain there's a problem with the wipers.

OR

You're in a crowded car and it's 50F and humid.The windows fog up but the driver refuses to turn on the a/c because he 'doesn't want to be cold'...... And the same person talks about how he'd set the HVAC to 'defrost' in his old 70's or 80's GM car and the windows would stay clear. You explain that the 'defrost' setting turns on the a/c setting and he tells you you're wrong because he'd move the temp button toward read and he'd stay warm. I used to try to explain but now I just don't bother.........

 

[rp2813]

My mom was one who would use the thermostat like a switch for the heater.  It drove my dad nuts.  When we first moved into our 1927 house with gravity furnace, it was controlled by buttons on a brass panel with red jewel lights.  My dad replaced it so quickly that I don't even remember if it had more buttons than ON and OFF, but in my vague visual memory, it seemed like more than just those two.  I'm sure my mom thought that arrangement was just fine, but I'm glad my dad prevailed.

 

Clearly, there are many people out there that simply don't understand the concept of a thermostat in any application, and there is no hope for them.

 

[DADoES]

 
The parents are like that with their car a/c.  Auto temp control but always at 60°F and they manually change the fan speed to moderate it.

I/ve had conversations with people to the same point about their window units.  One of granny's friends years ago discussing that her window unit gets so cold she has to turn it off.  I asked how does she have it set?  Fan on low and thermostat at 8 (of presumably 1 to 8) because "I want it to blow cold."  Hmmm, do tell.

Interestingly, the parents didn't have that misunderstanding with the window units in our growing-up house.

Just to say ... turning the heat higher or A/C lower *does* have an accelerating effect on two-stage or two-speed systems, heat pumps with auxiliary, etc.  Our growing-up house had two-stage electric-resistance heat.

 

[arbilab]

I used to try to explain but now I just don't bother....

Just noting there are no absolutes and anything is possible, this clunky thru-wall PTAC DOES cool faster if the setting is >5* below ambient.  It kicks both evap and cond fans up a notch above 'energy saving'.  There may also be 2-stage central systems as above.  Deluxe feature, salesman probably said it had that, buyer was 'impressed' but without the foggiest what it was.

 

Kind of unfathomable to 'us', but by far most people have no earthly idea how things work,

and no frame of reference by which it can be explained to them.

 

Back to topic, initial cooldown: Food safety.  Particularly before all fridges had fans, took a long time for room temp heat to migrate to the coldbox before the entire interior was in the 40* neighborhood.

 

[combo52]

Pre-Cooling Refrigerators ?

It was partly just being very serious and scientific about having customers use refrigerators properly.

 

I always tell customers to load the new ref immediately when delivering a new ref unless the food is in a better [ colder ] otherwise it is better off being in the new ref getting cold along with the refrigerator.

 

I guess if it were a Gas refrigerator you would be advised to wait a day for the darned thing to try and get cold, those things were very slow to cool and had about 0 reserve capacity.

 

John L.

 

[henene4]

Car temps

Are actually one of the things where with certain kinds of system setting it lower will actually cool down faster.

My Polo's AC system dosen't have a temperature control per se.
It's a simple dial that mixes air between what goes through the heater core, what goes through the AC and what is just outside air.

Thus, turning it down gives you a higher percentage of cold air mixed in and the higher the cooling power.
Heating vise versa.

 

[launderess]

Here's a page from Gibson "Market Master" all fridge. They recommend allowing refrigerator to run for at least 8-12 hours before loading with food.

Gibson Market Master series Owner's Manual (Page 6 of 20) | ManualsLib

www.manualslib.com

 

[ea56]

When we got our current refrigerator 3 years ago, a 15.5 cu ft. top freezer GE, BOL, we left it at the recommended temp setting, put everything back in the fresh food and freezer compartments and in less than 3 hours the fresh food compartment was 38 F and the freezer was 0 F and we already had ice cubes frozen.  And we’ve never moved the temp control since.  This little basic wire shelf, no frills fridge is quiet and efficient. 

Eddie

 

[rp2813]

The AC on my 2003 Subaru works the way I prefer -- the compressor cycles on and off based on where I have the dial twisted to -- there is no temperature setting.  I really dislike systems that simply mix in more outside air and leave the compressor running constantly.  That uses more gas, and gas is already overpriced here in California.

 

[warmsecondrinse]

"My Polo's AC system dosen't have a temperature control per se.
It's a simple dial that mixes air between what goes through the heater core, what goes through the AC and what is just outside air.

Thus, turning it down gives you a higher percentage of cold air mixed in and the higher the cooling power.
Heating vise versa."

Exactly, but that's already too complicated for many people to understand.

Complicating matters, many cars would turn on the a/c when the lever was set to "defrost" if the temps were above freezing. Most people would insist the a/c was not on because the setting was not labelled "a/c".

If the car had non-American controls and the a/c compressor had to be turned on manually it was even worse. NO amount of explanation would convince them that in cool, damp weather they could have clear windows (no interior fog) if they turned on the a/c and increased the temperature to put more heated air into the mix.

Whenever I tried to explain people would look at me as if I were speaking Ainu.

 

[DADoES]

 
Once in a while one runs across someone who has a clue.  A girl with whom I carpooled to college had an old Buick (her dad found it for her, she was thrilled).  The a/c didn't work (her dad planned to fix it).  She remarked one mild moist morning that "the defogger doesn't work because the air conditioner doesn't work."  Could be her dad told her that ... but either way.

 

[DADoES]

 
Car a/c systems typically have a temperature limiter on the evaporator that cycles the compressor to avoid a freeze-up.  I once hooked a small light bulb to the compressor terminals on one of my cars and placed it dangling in the footwell, it turned on/off with the compressor cycling.

 

[combo52]

Pre-Cooling A Refrigerator ?

I don't Care what the Gibson Manuel advises, these Manuels were written by men trying to find silly things for women to do and worry about.

 

Eddies experience in reply #13 is the way to start up a refrigerator, Yesterday our delivery helper was not available so I helped deliver two refrigerators to two group houses of men at Maryland University, and we just moved the food from one ref to the other, if anything the cold food helps the ref cool down more quickly.

 

John L.