Most economical way to run a freezer

Jolaaled

I've read a number of times on this forum, that it's best to keep your freezer full, to ensure maximum efficiency and lowest running costs.
Filling gaps in the freezer drawers with bread/bottles of water etc is sometimes also recommended.

However, today, I read on another forum that this advice is incorrect..

that it's best not to over-fill the freezer..and that any items create a load on the freezer, whereas air spaces are less of a load for the freezer.

Any ideas on what is the best way to go??

(PS..this article also recommended ..conversely..keeping your fridge only partly filled as it is more economical to have air circulation!).

Andy_WSM

First off, keep it set at -18C, any colder is unnecessary and wastes energy.

If it's an upright freezer then you don't want air gaps as cold air sinks, so whenever you open the door the cold air will "fall out" of the freezer and cool your feet. Filling it with bread or bottles of water eliminates these air gaps which helps alleviate this problem and means the freezer cycles on & off less (once it has cooled the initial load).

redkoatz

Jolaaled wrote: »

I've read a number of times on this forum, that it's best to keep your freezer full, to ensure maximum efficiency and lowest running costs.
Filling gaps in the freezer drawers with bread/bottles of water etc is sometimes also recommended.

However, today, I read on another forum that this advice is incorrect..

that it's best not to over-fill the freezer..and that any items create a load on the freezer, whereas air spaces are less of a load for the freezer.

Any ideas on what is the best way to go??

(PS..this article also recommended ..conversely..keeping your fridge only partly filled as it is more economical to have air circulation!).

I can't understand the logic of that, it reminds me of a debate I had with someone once about washing machines, who claimed that a washing machine with a full load took longer to wash. I said it didn't because if you run a particular cycle, lets say "quick rinse" regardless of how many items are inside the machine, it doesn't alter the length or intensity of the wash, my friend insisted it did.
This seems similar, you are saying the amount of volume being occupied inside the freezer actually puts more stress on the motor of the freezer which is working harder to freeze said volume?
Logically I can't see how this can be true. How is the freezer actually aware of how much of it's space is occupied?
Really doesn't it just work with thermostats? meaning once a desired temperature is obtained, the thermostats report that reading to the motor, which shuts off as the temperature has been reached.
As we know, heat travels through solid matter faster than air, because atoms are more sparsely distributed than in solid objects where the atoms are more tightly packed.
Working under that logic, the more items in the freezer then the easier it is to cool, and that desired temperature will be reached faster and thus the motor switches off.

However maybe it depends on where the thermostat is located? For example if it's located at the bottom of the freezer and items packed at the top restrict the movement of cold air to the top, then the motor would just carry on cooling as the thermostat at the bottom didn't get cooled enough yet?

but in general I would say no, you don't keep some empty space, you would fill it.

tronator

redkoatz wrote: »

I can't understand the logic of that, it reminds me of a debate I had with someone once about washing machines, who claimed that a washing machine with a full load took longer to wash. I said it didn't because if you run a particular cycle, lets say "quick rinse" regardless of how many items are inside the machine, it doesn't alter the length or intensity of the wash, my friend insisted it did.
This seems similar, you are saying the amount of volume being occupied inside the freezer actually puts more stress on the motor of the freezer which is working harder to freeze said volume?
Logically I can't see how this can be true. How is the freezer actually aware of how much of it's space is occupied?
Really doesn't it just work with thermostats? meaning once a desired temperature is obtained, the thermostats report that reading to the motor, which shuts off as the temperature has been reached.
As we know, heat travels through solid matter faster than air, because atoms are more sparsely distributed than in solid objects where the atoms are more tightly packed.
Working under that logic, the more items in the freezer then the easier it is to cool, and that desired temperature will be reached faster and thus the motor switches off.

However maybe it depends on where the thermostat is located? For example if it's located at the bottom of the freezer and items packed at the top restrict the movement of cold air to the top, then the motor would just carry on cooling as the thermostat at the bottom didn't get cooled enough yet?

but in general I would say no, you don't keep some empty space, you would fill it.

You're comparing apples with oranges. The term you're looking for is "heat capacity". Air has a much lower heat capacity than for instance water. So it takes more energy to heat the same volume of water than it takes to heat the same volume of air. It's the same for cooling.

But you also have to take into account that the more air you have in your freezer the more cold air gets replaced with warm air when you open it. All other liquid and solid objects in the freezer stay where they are and only their surfaces exchange heat with the environment.

I hope that makes sense

redkoatz

tronator wrote: »

You're comparing apples with oranges. The term you're looking for is "heat capacity". Air has a much lower heat capacity than for instance water. So it takes more energy to heat the same volume of water than it takes to heat the same volume of air. It's the same for cooling.

But you also have to take into account that the more air you have in your freezer the more cold air gets replaced with warm air when you open it. All other liquid and solid objects in the freezer stay where they are and only their surfaces exchange heat with the environment.

I hope that makes sense

I wasn't looking for any particular word.
The best skill in communication is getting a message across, not using terminology, which regardless of what you use, the same principle applies. The reason solid objects transmit heat better is how densley packed the atoms are. Pretty basic stuff in scienece, so anyone whos been to school should be able to comprehend it.

Not sure of the relevance of the second part of your post, talking about the surface area of the items in the freezer getting slightly warmed up because of cold air being replaced by warm air? Don't you think that just unnecessarily complicates the topic? less items =bad more items =good
Or am I misreading something that contradicted my point?

Pincher

Ah yes, explaining Physics.

http://en.wikiquote.org/wiki/Talk:Richard_Feynman
On p52 the book says:
Fenman was a truly great teacher. He prided himself on being able to devise ways to explain even the most profound ideas to beginning students. Once, I said to him, "!!!!!!, explain to me, so that I can understand it, why spin one-half particles obey Fermi-Dirac statistics." Sizing up his audience perfectly, Feynman said, "I'll prepare a freshman lecture on it." But he came back a few days later to say, "I couldn't do it. I couldn't reduce it to the freshman level. That means we don't really understand it."

I was doing a presentation during my "freshman" year, i.e. 1st Year BSc in a tutorial to my fellow students.
I said:" If you remember from your O Level Physics, ......."
And the response from the audience was to the effect that it was wrong of me to assume 1st year students (on a BSc course with electronics hardware modules) should have some science knowledge to O Level standards.
Yes, a Nobel Laureate like Richard Feynman will definitely have the wit and patience and didactic nowse to circumvent any pre-conceived notions based on received wisdom, but he is also far too intelligent to know he has better things to do than to spoon feed somebody who is just sitting in a pub and want a chat.

tronator

redkoatz wrote: »

I wasn't looking for any particular word.
The best skill in communication is getting a message across, not using terminology, which regardless of what you use, the same principle applies. The reason solid objects transmit heat better is how densley packed the atoms are. Pretty basic stuff in scienece, so anyone whos been to school should be able to comprehend it.

You're still mixing things up. I gave you the right word so you could look it up on Wikipedia by yourself. The heat capacity is different from thermal insulation. In short, the heat capacity describes how much energy an object can store, whereas the thermal insulation describes how good or bad an object can transmit this energy. So far the communication

I brought it up because you were saying, that it would take the same amount of time and energy to cool an empty and a full freezer like it takes the same time to wash an empty and a full washing machine. That's simply wrong.

redkoatz wrote: »

Not sure of the relevance of the second part of your post, talking about the surface area of the items in the freezer getting slightly warmed up because of cold air being replaced by warm air? Don't you think that just unnecessarily complicates the topic? less items =bad more items =good
Or am I misreading something that contradicted my point?

The second part of my post was a quite important one. The more you put in your freezer and fill any gaps between the items the less energy you lose when you open it.

But you need to consider what wastes more energy, putting more stuff in the freezer which you normally wouldn't or losing the energy from the air escaping. Since the air has a low heat capacity it might be not that much enrgy you lose, but then the ratio volume/surface area comes into play and you lose more energy by the heat exchange between the warmer air and the frozen goods.

I didn't make any measurements, but my feeling says a full fridge is better. Or a combination of both . Fill the freezer as much as you need and fill the empty space with bubble wrap (or any other stuff with a low heat capacity and a high thermal insulation), so that the insulating air can't escape when you open the freezer. But keep in mind that it takes longer to freeze items when you wrap them in bubble wrap. So either freeze them first and wrap them later or only fill the gaps with bubble wrap.

redkoatz

ahh i get you now. you misunderstood me, I was only saying how unlike a washing machine, where the used space inside the drum doesn't appear to effect the length of the wash, whereas with a freezer it does, because the more solid objects in the freezer, the better the cold is transferred from one object to another. I hadn't even considered insulation and such, but with that in mind, maybe putting boxes of say 'fish fingers' inside a plastic tupperware box and then putting that into the freezer would help with the thermal insulation part aswell, seeing as the cold air immediately surrounding the items will be trapped in place when you open the freezer door and of course the benefit of doing that with every item, is that you don't have to waste as much time (with the cold air escaping from an open door) while you are busy stuffing bubble wrap in there. Ive seen some rather large tupper ware boxes that are almost identical in size to a freezer shelf, I would imagine you can cut down on how much time you need the door open to only a few seconds, if it's just to insert/replace a large tupperwear box. My dad claims that chest freezers are actually more economical, as no cold air is released when you open the door, but then they are very big, so who knows, i've never looked it up.

sk240

The real saving with a freezer is keeping the ice at bay, make sure you defrost it regularly, ice is actually quite insulating and the freezer will have to run much harder to achieve the temperatures.
I thought my electric bill was a bit high, defrosted the freezer and cut my bill by £5 a month!
Keeping the freezer full will make a slight difference because the stuff will conduct the heat away better than just air, also more stuff in the freezer limits the air that's drawn into the freezer when you open the door, again reducing the speed the ice builds up.

lstar337

tronator wrote: »

my feeling says a full fridge is better.

My stomach says something similar.

theEnd

Either way, the difference would be tiny on a very cheap to run appliance.