I am puzzled by a section of Gregg Esterbrook’s January 3, 2006 Tuesday Morning Quarterback column on www.nfl.com. I enjoy his column for both his football analysis and his clever asides about life’s absurdities, but these week’s aside threw me. It says in part,
“Let’s Turn on the Air Conditioner and Build a Fire: TMQ lives in the suburbs and has an old refrigerator in the garage – having a lot of worthless stuff in the garage makes me feel patriotic. If you put a refrigerator in the garage, the compressor, which is designed to work at room temperature, shuts down when the air drops near the freezing mark. Then you have the absurdity of a device designed to keep things cold becoming warm inside because it’s cold outside. But never fear, suburban technology is here – in the form of the new Whirlpool garage refrigerator. The garage refrigerator contains a heater that warms the compressor when the temperature dips below freezing. Yes, a device designed to keep things cold contains a heater so it will continue to make cold air when making cold air is unnecessary because it’s cold out. Only in America!”
I’m no expert on appliances, but I think this is flat out wrong. Even if the refrigerator’s compressor doesn’t work when the machine is out in the cold, the stuff inside the fridge will remain cold because the ambiant air temperature is still cold. That is, the stuff in the fridge can’t heat up to a degree warmer than the air outside the fridge, and that air is by definition freezing cold, therefore the stuff must still be cold too.
Different versions of this have come up here before. Your reasoning is largely correct in theory and application. There is still some heat transfer even in an insulated box and if it is warmer inside the fridge than out, the fridge will slowly cool down. Garage refrigerators work just fine all across America under a very large range of outside temperatures.
The heater is not for the compressor, but for the inside of the refrigerator to keep it from getting too cold.
If where you live the winters don’t get cold enough for the inside of your garage to drop below, say 25 F, you may not notice anything bad from a normal fridge in the garage as your pop and beer probably won’t freeze.
When the garage gets below freezing, the fridge contents stay nice and cold, since there is no heat source. And given that the inside is cold, the compressor actually has no need to turn on. The problem with garage fridges is that as it gets even colder, the inside of the fridge drops further and further below the desired temperature. And then eventually your pop cans and beer bottles freeze and explode all over the inside of your refrigerator. And you have to wait until it gets warm to clean it out because there was no way I was cleaning up that mess when it was -10F.
Lots of freezers work great in the cold garage, but it’d suck to have a garage fridge full of exploded water and soda bottles, so it ain’t silly.
The fridge should keep beverages at 35-40 degrees. We generally think a proper fridge should ‘keep things cold’, but when it is 11 degrees F outside, 40 isn’t “cold”.
Like vending machines outside, the machine should keep food/drinks the 'proper temperature", and that requires heat or cold cycles, depending on the outside temps.
I had this problem with my chest-type deepfreeze. Within a certain very cool range of air temperatures out in my garage, it wouldn’t keep food frozen. Since it was moved inside two years ago it has worked as it should.
While the Whirlpool garage refrigerator does indeed appear to have a heater to heat the interior of the refrigerator (in addition to having heaters in the walls to control condensation on high humidity days), there is another consideration when operating refrigeration equipment in low ambient temperature conditions.
The condensor coil and compressor are designed to work within a certain pressure range. As the ambient temperature drops, so does the condensor pressure. There are at least two usual options used in order to keep this pressure from dropping too low: Fan cycling and hot gas bypass, both which limit the amount of heat the condensor transfers. It seems counter intuitive, but it’s done to prevent damge to the compressor.
I don’t know if these are used on household refrigerators, but it’s common in commercial work.
It is unclear to me why this is only for self defrosting fridges. I had thought that self defrosting fridges use a small electric coil to defrost. This note makes me think that some act like a mini heat pump to self defrost, with the hot coil inside the fridge and the cold coil outside. I would have thought an electric coil would be cheaper.