whats the cause of icing evaporator coils
i am having a problem with at least 3 cold rooms icing the evaporator coils. All i need is a long term solution to my problem.
yours rodney :confused:
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whats the cause of icing evaporator coils
i am having a problem with at least 3 cold rooms icing the evaporator coils. All i need is a long term solution to my problem.
yours rodney :confused:
hi rodney, when you say icing, what does it look like? is it the snowy fluffy stuff that might indicate poor door seals or broken insulation, or is it the hard stuff that could indicate poor defrost or blocked drain. incorrect gas charge can also cause icing.
So does leaving the door open. Our biggest icing up problem in supermarket coldrooms used to be that the damn staff would NOT close the door behind them! ;-)
Hi Rodney.
Icing on the evaporator is a result of many problems,
apart from what was said before, you can add,
fan speed is too low,
lack of refrigerant,
door seals, broken,
room set point is too low,
head pressure is too low,
dirt blocking the air,
Is it all over the evaporator?
Only near the TEV?
What is your set point?
What is your evaporating temp?
What is your condensing temp?
Is there a defrost cycle?
Is the suction line frozen too?
Compressor hot/cold?
Is the currant draw, within the normal?
Are you a fridgy?Quote:
All i need is a long term solution to my problem.
If yes, then start with answering these questions and I'm sure, in no time, we will be able to help.
If you are using a defrost timer to achieve a defrost, what is the duration of the defrost and the period between defrosts?
If you are using a presure switch to cycle the compressor on/off then what is the cutin/cut out points and what gas are you using?
Are the evaporator fans on or off during defrost?
Do the evaporators have heaters? Heaters are not usually fitted in cold room applications.
If you answered these questions and the others above we may find a solution to your problem.
Cheers,
Feeze
Quote:
Originally Posted by Feeze
:)
It looks like " off cycle defrost " with full fans on is common in your neck of the woods Feeze
Here in UK its rare to find a cold store these days without heaters.
Especially now its becoming increasingly mandatory for cold stores to achieve -2 C operations.
Aiyub,
With the low room temperature and generally low ambient you guys experience defrost heaters are necessary.Rodney is from Zimbabwe, a country with tropical weather.
Thanks for that bit of info though.
It seems like Rodney is not going to reply to us, maybe he has power problems amongst other. :rolleyes:
Feeze.
hie guys
http://www.refrigeration-engineer.co...wreply&t=2548#
Smilie
thanks to everyone who helped me in knowing what might be the causes of icing
rodney
hie
Can anyone supply me with text books that suit the tropical whether here in zimbabwe. Am sitting for december exams {UK BASED EXAMS}, a diploma in refrigeration. Thats the main resean why i need text books
i promise to reply in time guys.
yours in need
rodney from southern africahttp://www.refrigeration-engineer.com/forums/images/icons/icon14.gif
Thumbs up
Probably too simple but make sure you have a 'P' trap in the drain line.
If you don't all the warm damp air rushes in and trashes £20K worth of coils.
If you start running defrost times out of 'normal' delay periods its a pretty good indicator followed by suspiciously bent fan blades and burnt out motors.
Also had the locals brewing up for iced tea (in 20 litre buckets) before the management arrived and chilling it in the freezer store. Frost everywhere! :) But thats another story....
Head pressure is the pressure measured at head of the compressor.
The same as the discharge at the discharge valve.
Chemi :)
Head presure is nothing more than discharge pressure of the compressor. Some people will use the term to describe the differential pressure across the compessor.
As for icing the coils, what are your operating conditions, coil ET, pressure, and room temp.
Some of the obvious questions have been ask...
drain lines trapped?
door kept closed?
room properly sealed at joints?
is the product being brought in too wet?
do you have a defrost, off-cycle, electric or hot gas?
Is defrost time sufficent to allow a complete defrost?
Let us know what you find.
Ken
( QUOTE= C BAGTAS )Quote:
Originally Posted by Aiyub
You can check also the gas, if less gas it will start frosting after expansion valve,in continous operation the whole evaporator will get frost.check also the flow of air may be your fan is defective or your evaporator is dirty.