Thursday, June 25, 2009

"Mystery of your frost free fridge revealed"

I love to read advice and information from other folks in the field. You can learn so much when you are open to information and a little constructive criticism. So, that said, here is a post I found on the net that was absolutely wonderful! It is written in laymen's terms so most everybody can get it. It gets better as it goes too....I have the writer's credit at the end...Good job and well done Nestor!
Enjoy!
ArchAngel

The mystery of your frost free fridge revealed:
or "What every owner of a frost free fridge should know":

The way to tell the difference between a frost free fridge and a manual defrost fridge is that a frost free fridge will have separate freezer and fresh food compartments, whereas a manual defrost fridge will have a freezer box at the top of the fresh food compartment. The fundamental difference between a "frost free" fridge and a manual defrost fridge is that a frost free fridge has an automatic method of defrosting itself.

In a manual defrost fridge the refrigerant evaporates and absorbs heat as it flows through the channels molded right into the evaporator box at the top of the fresh food compartment. Since the refrigerant is evaporating in those molded channels, the evaporator box will be the coldest thing in a manual defrost fridge, and that is where frost will accumulate. You defrost such a fridge by unplugging it or turning the thermostat to "defrost" or "off" and waiting for the frost on the freezer compartment to melt.

In a frost free fridge, there will be an evaporator coil which is hidden out of sight which serves the same purpose as the "freezer box" in a manual defrost fridge. The refrigerant evaporates in that evaporator coil, absorbing heat as it does, thereby making the evaporator coil very cold. There will also be an "evaporator fan" which sucks air through that evaporator coil and blows most of the cold air into the freezer compartment, and a little of it into the fresh food compartment. Some frost free fridges have adjustable baffles that allow you to set the proportion of cold air sent to each compartment. The reason why the freezer compartment gets colder than the fresh food section is because it normally has more cold air flow through it.

Every time you open the door of the fresh food compartment or freezer compartment of your fridge, you let some cold dry air out of your fridge and some warm moist air in. The moisture in the air you let in is what causes frost to form on the freezer compartment of a manual defrost fridge or the evaporator coils of a frost free fridge. Ice and frost forming on the evaporator coils of a frost free fridge reduce the efficiency of the fridge because they act as insulation and prevent heat transfer between the cold aluminum coils and the air the evaporator fan is circulating over those coils and throughout the fridge. And, of course, frost reduces the amount of air flow through the coils.

This "automatic defrost system" consists of three components: the defrost timer, the defrost heater and the defrost thermostat. These three components work together to melt the frost off the evaporator coil.

Let's look at each of the three components in the automatic defrosting system of a typical frost free fridge:

1. THE DEFROST TIMER:
Just like you have a timer in a clothes washer that controls the valves and motors at each stage of the clothes washing cycle, every frost free fridge will have a defrost timer. The defrost timer in a frost free fridge is much simpler than the timers in washing machines or dish washers because there are fewer things in a frost free fridge for the timer to control. The defrost timer's job is to shut off the fridge's compressor and evaporator fan (together) for about 20 to 35 minutes every 8 to 12 hours and divert the power to the defrost heater instead.

2. THE DEFROST HEATER:
The defrost heater is just an electric coil heater that's positioned close to the evaporator coils so the radiant heat melts the frost off the evaporator coils. The melt water then drips down and is carried by a sloping drip pan to a drain. A rubber hose usually running along the back of the fridge carries this melt water down into a receiving pan sitting on top of, or around, the usually warm compressor motor. The water is then re-evaporated back into the room by the waste heat from the compressor. You can redirect this melt water into a drain and use your frost free fridge to dehumidify your house a little.

3. THE DEFROST THERMOSTAT:
Once the frost is all melted off the evaporator coils, continued heating results in a rapid rise in temperature in the vicinity of the evaporator coils. The job of the defrost thermostat is to detect that temperature rise and break the circuit to the defrost heater, thereby preventing further heating and possible damage to the plastic and foam parts near it. (This is normally accomplished by simply wiring the defrost thermostat in series with the defrost heater.) Once the defrost thermostat breaks the circuit to the defrost heater, the fridge will then just sit there and do nothing at all until the end of the defrost cycle when the defrost timer shuts off power to the defrost circuit and restores power to the compressor and fan circuit once again.

THIS IS WHERE I FLY OFF ON A TANGENT...

This web site's server is telling me the post is too long, so I will continue it in another post to follow...

Last edited by Nestor_Kelebay; 07-10-2008 at 01:29 AM.
http://www.diychatroom.com/f47/help-my-admiral-refrigerator-leaking-water-23441/

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