HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Comments
View Comments: Oldest First|Newest First|Threaded View
Page 1/4  >  >>
Mydesign
User Rank
Platinum
Hot air surrounding the freezer
Mydesign   7/3/2012 5:14:51 AM
NO RATINGS
1 saves
"There's a heater located inside the freezer to heat up the coils to prevent freezing"

Richard, that's a new info. But I know for cooling the freezer, compressor has to work a lot which ends up in pulling more hot air to surrounding.

tekochip
User Rank
Platinum
Heating to cool
tekochip   7/3/2012 8:41:32 AM
NO RATINGS
The purpose of the defrosting heater is to melt the ice off the coils that has accumulated due to moisture from opening the door and allowing the warm, moist air to enter.  Any ice on the coils makes them less efficient, so you like to keep them clean. Back when I was a young lad (there was a time when I was) you'd have to defrost the freezer yourself by turning it off and maybe placing some hot pots inside. Water would run everywhere and you had a big mess. It was a bit of a pain and you typically wouldn't do it until enough ice built up that the door wouldn't close or you couldn't put anything in the freezer. Freezers were smaller back then, though, because frozen foods were not as popular. Anyway, now refrigerators have heaters that melt the ice off, and then there's a tube that allows the water to collect in a pan near the floor. Warm air from the compressor blows across the pan and allows the accumulated water to evaporate. Simple refrigerators have a mechanical timer to control the defrost cycle, but more expensive appliances have clever units that monitor when the door is open and try to defrost while Mr. Sandman is tugging at your eyelids. Even more sophisticated units try to guess how much ice is on the coils, since running the defroster is a huge waste of energy.

DW
User Rank
Iron
Refrigerator Mysteries
DW   7/3/2012 10:34:07 AM
NO RATINGS
I purchased a backup/extra storage refrigerator to put in my garage last fall.  The garage is unheated space. One day in winter, I noticed the garage refrigerator was not cooling - the compressor was not running. After looking at the owner's manual and talking to the appliance service department, I learned that the refrigerator requires an optional heater if it is installed in an unheated space where the temperature may fall below 40 deg. F. This is not the defroster heater which is required to prevent ice build-up regardless of where the refrigerator is installed. Perhaps it is a booster to the defrosting heater? I had never heard of this before last winter. Does anyone know why this optional heater is required for a refrigerator installed in an area where the temperature may fall below 40 deg F? Has this always been a requirement or is this a result of replacing freon with other coolants?

DW

SlideRuleFarmer
User Rank
Iron
Re: Refrigerator Mysteries
SlideRuleFarmer   7/3/2012 11:08:19 AM
NO RATINGS
I live in Central Minnesota and it does get a little colder up here, -40C/F is not unheard of. We have a fridge in our barn to store eggs from our hens until they are sold. Like an AC unit a fridge only moves heat from one area to another, when it is below the freezing point things will freeze in a fridge. So every November when the temps finally fall below 32F I simply slip a 9W CFL in the fridge, it generates enough heat in the fridge to keep everything from freezing. And if it starts to warm up beyond the setpoint of the fridge thermostat then the fridge does it's job and moves the heat inside to the outside. I even have to keep my liquid hand soap and other hand cleaners in the fridge during the winter, it's hard to wash your hands with a block of frozen soap! Come April I can finally put out the CFL. Just part of the fun living living in the great white north.

TC

richnass
User Rank
Blogger
reponses to responses
richnass   7/3/2012 12:44:59 PM
NO RATINGS
Tekochip: that's pretty much the same thing my repairman told me. I get it, but it seems to be wildly inefficient.

DW: I also have an old unit in my unheated garage. I'm in NJ, so it gets pretty cold. I hope I'm not putting the whammy on myself, but I've never had an issue with that refrigerator and it has no extra heater.

Here's more than you wanted to know. When I bought my currewnt frig 12 years ago, I sold the old one to the next door neighbor for their garage for $100. They moved, and the new neighbors didn't want it, so we took it back. Please don't tell anybody about the 100 bucks.

SlideRuleFarmer: time to move someplace warmer.



tekochip
User Rank
Platinum
Re: reponses to responses
tekochip   7/3/2012 1:46:31 PM
NO RATINGS
Consider the $100 rent.

 

 

Charles Murray
User Rank
Blogger
Re: Heating to cool
Charles Murray   7/3/2012 5:04:25 PM
NO RATINGS
Freezers that are non-self-defrosting still exist, and I actually have one in my garage, Tekochip. You're right about the process of defrosting the fridge manually -- it indeed happens when the door doesn't close. And, yes, manual defrosting is a mess. To fully appreciate the value of self-defrosting fridges, you have to do it manually once.

tekochip
User Rank
Platinum
Re: Heating to cool
tekochip   7/3/2012 7:20:34 PM
NO RATINGS
Back when I had one I hated doing it so much that I would wait until the door wouldn't close anymore.  Of course, I'm sure I wasn't much of a housekeeper back then.

Chipmonger
User Rank
Iron
Heaters there for a reason
Chipmonger   7/3/2012 8:44:49 PM
NO RATINGS
@tekochip - yes you are correct the heater is for the "automatic defrost" feature. The simple fridges use a clock motor that triggers a switch that turns on the heater every 24 hours. We use to turn the motor's shaft so that defrosting would take place at night when the familys in bed. 

@DW - The optional heater is to keep the refrigerant from turning into a liquid. This prevents damage to the compressor since it is designed to compress gas and not liquid refrigerant. I have split air conditioners and they have these heaters in the ouside compressors that draw many watts of power 24 x 7.

@Charles Murray - Leaving the fridge door partly ajar does not defrost the fridge but actually makes it worst. The fridge will continue to run and actually run longer since it senses a higher than normal temperature. With the door open, outside moisture is drawn in which then forms ice on the cooling coils cutting off circulation. In the end, the cooling coil becomes completely encased in ice ncessitating a manual defrost.

Jack Rupert, PE
User Rank
Platinum
Re: Heaters there for a reason
Jack Rupert, PE   7/4/2012 2:18:42 PM
NO RATINGS
Chipmonger - Maybe it's because I haven't had the need to buy a freezer in a while, but your response to tekochip through me off.  A "simple" refrigerator now has a clock too?  My "even simpler fridge has the feature you mentioned but without a clock set to it.  Periodically you can hear the frost dripping off and being vaporized.  At least that is what I've been told that I'm hearing.

Page 1/4  >  >>


Partner Zone
Latest Analysis
Take a look at the top 20 US undergraduate engineering programs. Then tell us -- did your school make the cut?
Producing high-quality end-production metal parts with additive manufacturing for applications like aerospace and medical requires very tightly controlled processes and materials. New standards and guidelines for machines and processes, materials, and printed parts are underway from bodies such as ASTM International.
Engineers at the University of San Diego’s Jacobs School of Engineering have designed biobatteries on commercial tattoo paper, with an anode and cathode screen-printed on and modified to harvest energy from lactate in a person’s sweat.
A Silicon Valley company has made the biggest splash yet in the high-performance end of the electric car market, announcing an EV that zips from 0 to 60 mph in 3.4 seconds and costs $529,000.
The biggest robot swarm to date is made of 1,000 Kilobots, which can follow simple rules to autonomously assemble into predetermined shapes. Hardware and software are open-source.
More:Blogs|News
Design News Webinar Series
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
7/17/2014 11:00 a.m. California / 2:00 p.m. New York
6/25/2014 11:00 a.m. California / 2:00 p.m. New York
5/13/2014 10:00 a.m. California / 1:00 p.m. New York / 6:00 p.m. London
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Sep 8 - 12, Get Ready for the New Internet: IPv6
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Class: September 30 - October 2
Sponsored by Altera
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service