I have always wondered about this one... Refrigerators are one of the top energy consumers in homes. In Northern climates, the outside temperature is colder than indoor temperature at least 6 months of the year.
Why aren't they designed with "heat" exchangers to benefit from cool if not frigid external air?
Even in warm climates (or summers) why isn't the same principle used to vent the warm air from the compressor & coils outside rather than loading the AC?
Presumably this could all be done by putting the evaporator coils outside which would in turn decrease (or eliminate if cold enough) the draw on the compressor during winter months.
Of course, installation might be a little more expensive, but with all the focus on green-this and green-that why isn't this being done?
Because it's impractical and adds to the expense. Besides that it wouldn't make a huge difference in the economics of operation seeing you are not cooling more than 30 cubic feet for a home fridge.
When you consider commercial refrigerators/walk in coolers and freezers and refrigerated displays in grocery stores, 99 percent of those have a remote condensing unit.
A little more expensive? The cost of the install of a coventional refrigerator is zero, you just plug it in. I replaced mine last year with a 23 cft side by side with water and ice at the door. Operating cost is about $95 a year. How much do you think you're going to save in operating costs by moving the condenser outside? In many houses you'd have to run how many feet of refrigerant tubing to get from the fridge to a suitable location to house the outside unit? Factor in installation costs (see the other thread here about permitting requirements for similar installs) a more complex system, more points of failure, shorter life due to exposure to the elements and you clearly have a non-starter.
Also, what happens when it's 10 degrees outside? A regular refrigerator won't operate below a certain ambient temperature because of issues with the refrigerant and compressor.
If my freezer wasn't dumping hot air into the kitchen then for the 6 months it's cold outside I'd just be paying to heat that room by other means anyway.
Besides, any modern bells-and-whistles replacement would likely be built in a country with a poor environmental record, shipped halfway around the world to me, and be built to the same shitty standards as everything seems to be these days - such that it has a lifespan better measured in months rather than decades, and I'd be buying another one quickly, then another...
Yes: Cool idea. Maybe.If fridges could draw in (and exchange) cool outside air instead of using electrcity. But some refrigeration and air controls would still be needed. Not sure the saving would be significant if at all?
And with existing conventional electric fridges! Within the house all the electricity used by the fridge ends up as heat. In our cool Newfoundland climate some heating is needed most months of the year.
So in a house that is electrically heated (as most are these days) the fridge heat merely replaces that from the electric heaters or other means used for heating the home.
A fridge is basically an electric motor driving a pump that takes heat out of the inside of the fridge and pumps it into those coils on the back of the fridge. It's a heat pump. The motor also wastes some of it's input (nothing is 100% efficient); it gets a little warm and that heat stays within the house.
By putting say the coils outside might mean the fridge would run less, thus saving electricity. But outside during a cold winter would basically waste that heat outdoors. Warmth that originally leaked into the fridge from the house and/or every time its door was opened, being pumped outdoors. Same thing as running an air conditioner except in this case it's only the fridge interior that is being cooled not a room!
And since a 300 watt fridge can pump something say of the order of
1000 watts of heat; better IMO in cold weather to keep all the energy used by the whole system within the house.
In a very hot climate the idea 'might' have some merit, if the cost/ complexity was reasonable? But pumping fridge heat outside into say 30 or 40 Celsius (90 to 110 F) atmosphere (Does it EVER get that warm here?) outside might mean the fridge would have to run longer; thus using more electrcity!
Overall the best course might be to have bulk of ones house underground and utilize any/all sources of energy (mainly electricity these days) entering it as a source of warmth. One of the bigger 'wasters' at moment being clothes dryers which chuck their warm damp air outside. But anywhere else in the home that moisture can cause mould/rot. That's why ventilation (especially attics) is so important.
Have seen a few homes here where there was a cold room built out fom the basement, say under the front steps that stayed something close to the temperature of a typical fridge. Useful for beer, potatos etc.
A refrigerator in a closed environment (in a home) will not only use electric to keep it cold on the inside, but 100% of it's losses are heat that is put into the home. You can't make anything cold. You can only remove the heat and put the heat somewhere else. So it takes the little bit of heat inside itself and puts it into your home, just like a heat pump. Also every watt it uses is turned to heat that also warms your home. The only way to benifit from cold outdoor air would be to put it outside. But then we sometimes run into other problems.
Using warm or hot outside air will make it run longer and less efficiently. If there would be any savings, it would be so small that it wouldn't be worth the trouble.
*You reminded me of something that I saw in several homes and apartments in Sweden many, many years ago. In the kitchens they had a dedicated cabinet that had a vent pipe to the outside. This made the cabinet cold enough to keep things fresh, but not frozen. The winters are cold, dark and long there so these cabinets could be used for many months.
It would be real complex and an expensive instal, it would almost have to be a frige and exterior wall section sold as a unit, so when its a certain point above inside room temp outside it wont be as efficent as the cooler inside air cooling the coil and it would have to know if AC is on to decide for it self what to do.It would have to computinside, outside temps, AC on or off, heat on or of, so how does it switch back and forth to use inside or outside air, and insulate and seal the opening to withstand winters cold and wind to high R values. It could be done but a frige would cost thousands and would you ever get a payback. I could see some custom room frige using outside air in winter with vents that operate by thermostat, that would cost little. In alaska the have real efficent friges, the outdoors.
CY: It does make sense, to me. It would be possible to put the refrig backed up to external wall. Some kind of gasket around the exterior of the fridge. Draw outdoor air for the condensor. Winter time, that would provide better cooling. Summer, to dump the heat outdoors. Window AC do that. Why not refrigerators?
CY: I suspect you mean condensor coils, but I know what you mean.
CY: Coordination between fridge makers, and home builders, comes to mind.
The electrical operating expense of a domestic refrigerator isnt high enough to justify modding it as you described. If you could find a suitable way to bring in cold outdoor air into the fridge while exhausting the fridge interior during winter months, it would save some money . Im sure someone has tried it at some time in the past.
I heard over 20 years ago that large grocery stores vent the condenser heat to outside in the summer - the refrigeration does some of the space cooling. In the winter they capture the heat and blow it back into the store for space heating.
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