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1/22/2020 12:12:56 PM
Posted: 1/18/2015 10:57:15 AM EST
mine seems to not be working. period
humidity rose above 70 percent as the basement reached 50 degrees.
i have the following unit. it is cold weather rated, yet it seems to not be working at all in the colder basement temps.
what gives?

the unit works if it is in a warmer area. i also tried the other dehumidifier i have on the other side of the basement and it does the same as the unit in question.
both are frigidaires
http://www.frigidaire.com/Owner-Center/Product-Support--Manuals/?productCode=FAD704DUD
Link Posted: 1/18/2015 11:00:04 AM EST
Dehumidifiers are poor heaters, they put out a little but cannot keep an area warm. What happens in the cold is icing, the cold side cannot wring humidity out as effectively due to icing.

70% is relative, at 40F, that is a dew point of around 35 F. So basically a three degree window means not much dehumidification is possible.
Link Posted: 1/18/2015 11:02:37 AM EST
i have an old sears dehumidifier that blows hot air as it runs
Link Posted: 1/18/2015 11:11:56 AM EST
Yes, they do consume electrical energy, turning it into heat energy a tad less than a 1:1 ratio due to latent heat of condensation of water produced.

They lose efficiency as temperature drops because the window of condensation to depositation (ice) narrows. Physics.
Link Posted: 1/18/2015 11:13:22 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Keith_J:
Yes, they do consume electrical energy, turning it into heat energy a tad less than a 1:1 ratio due to latent heat of condensation of water produced.

View Quote
They lose efficiency as temperature drops because the window of condensation to depositation (ice) narrows. Physics.
yay, science.
Link Posted: 1/18/2015 11:19:29 AM EST
Yes. A large 500 cfm dehumifier will remove 100 pints per day at 68* and 70% humidity, 145 pints per at 80* and 70%. The same unit will only remove 20 pints per day at 50* and 70% humidity. While most are rated to 40* once you get below 50-55 don't expect much to happen. Heat and moisture control go hand in hand.
Link Posted: 1/18/2015 11:27:46 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Keith_J:
Dehumidifiers are poor heaters, they put out a little but cannot keep an area warm. What happens in the cold is icing, the cold side cannot wring humidity out as effectively due to icing.

70% is relative, at 40F, that is a dew point of around 35 F. So basically a three degree window means not much dehumidification is possible.
View Quote




its in a 10x20 foot room....
i guess the solution is to keep it at 65F like it is in summer when there is 0 issues keeping it dry in there.
the odd part is i dont see icing on the coils. it just isnt drawing the humidity out.
i have a space heater running in there now to see if that helps.
however i prefer not having those in there due to fire risk
Link Posted: 1/18/2015 2:04:59 PM EST


In a picture
Link Posted: 1/18/2015 2:33:43 PM EST
The temperature your running your dehumidifier in is too cold.

The freon in your dehumidifier changes from a liquid state to a gas state as it leaves the capillary tube and enters the evaporator (the part that gets cold and condensates).
When this change occurs, heat is transferred through convection from the atmosphere (room air) to the freon in the evaporator.
Freon, in a gaseous state, is cold. The transfer of heat causes it to return to a liquid state and the cycle repeats.

The evaporator condensates when it is cold and the atmosphere is warm (doesn't have to be hot). The fan in your dehumidifier draws air across the evaporator, which enables the the unit (dehumidifier) to remove moisture from the air through the condensation/convection (refrigeration) cycle.

If the atmosphere (room temperature) is too cool, the refrigerant (freon) will not heat up (return to a liquid state) and your dehumidifier will not work. It is not uncommon for thick ice to form on the evaporator in this case.


Also, if the closed system (tubes, evaporator, condenser) have a leak, the result is the same and it will not work properly.

A defective compressor may also be the culprit.

Hope this helps.
Link Posted: 1/18/2015 4:09:28 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By yankee43:
The temperature your running your dehumidifier in is too cold.

The freon in your dehumidifier changes from a liquid state to a gas state as it leaves the capillary tube and enters the evaporator (the part that gets cold and condensates).
When this change occurs, heat is transferred through convection from the atmosphere (room air) to the freon in the evaporator.
Freon, in a gaseous state, is cold. The transfer of heat causes it to return to a liquid state and the cycle repeats.

The evaporator condensates when it is cold and the atmosphere is warm (doesn't have to be hot). The fan in your dehumidifier draws air across the evaporator, which enables the the unit (dehumidifier) to remove moisture from the air through the condensation/convection (refrigeration) cycle.

If the atmosphere (room temperature) is too cool, the refrigerant (freon) will not heat up (return to a liquid state) and your dehumidifier will not work. It is not uncommon for thick ice to form on the evaporator in this case.


Also, if the closed system (tubes, evaporator, condenser) have a leak, the result is the same and it will not work properly.

A defective compressor may also be the culprit.

Hope this helps.
View Quote



indeed it does. i will try the unit again in a warmer environment.
and check on the room now as it has had a space heater running all morning now. if humidity drops i know its temp related.
Link Posted: 1/18/2015 6:29:43 PM EST
room is now 60F and 48 % humidity
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