View Full Version : Evaporator Icing Up

07-12-2002, 12:23 AM
Got a freezer room, about 20 feet by 20 feet. Two Blowers each running on independent compressors.

Evaporators icing up badly. When one system stops for defrost other one may be running. Is that why

Do both systems have to stop at the same time and carry out their defrosts together??

07-12-2002, 12:52 AM
It is probably best Aiyub, to defrost them together in such a small room. When one is in defrost, even though the fans are stopped, a lot of moisture enters the box. If the other one is stil refrigerating it will entrain a lot of that moisture.

This may not necessarily be your problem, but I would recommend defrosting them together as a first step.

07-12-2002, 01:18 PM
Hi, Abe:)
is this the same room that is breaking the fan mounts?
Door openings on small rooms like this, especially will coolers above the door will lead to heavy snowing/frosting of coolers.
Better door management would be a start, if that is unacceptable to the customer a de-humidified anti-room before the entrance to the room will sort the humidity out.
Regards. Andy.

08-12-2002, 02:57 AM

It is the same room that has the broken mounts. I know the doors are left open for long periods of time. Big door left open, which opens to the outside of the building and they load up the trucks . Product is ice cream.

Two fan motors have already burnt out recently. a third one is now hitting ice and I can hear it knocking.

And, I hate working inside the room at that temperature. My hands freeze up and I hate it.

How do you do it??? I ask

Maybe you got thin blood

08-12-2002, 05:54 AM
And, I hate working inside the room at that temperature. My hands freeze up and I hate it.

Me too. But I also hate changing a tire in St. Louis during winter.

I don't think managers understand the degree of difficulty a technician undertakes in a day-to-day operation. I don't think that the customer who pays the bill understands it either.

09-12-2002, 12:07 AM
Hi, :)
working in defreeze rooms is my least favorite part of the job, especially as I have poor circulation in my hands at the best of times.
I wire the system up for a permanant defrost (most are heaters or reverse cycle). Then I don my padded boiler suit and a body warmer and a coat, along with my 3M hat and gloves. After that it is just a matter of mind over body.
Working in deep freezes isn,t that bad if you are prepared with all the gear in the safety cage (most of my work is in large stores of 30' reach trucks), bring all the gear up and then some and you will have about half of what you need, remember the customer still wants the thing fixed yesterday regardless of how cold or high up you are!
Thats my way of dealing with the cold others have their own thoughts, but that's how I get my work done.
Regards. Andy:(

25-01-2003, 03:00 PM
Dear Aiyub,

Just saw this one - maybe too late for a reply - but will give my 2 cents worth anyway!!

Door management is always a major problem with freezers ( as Andy rightfully put it!) Especially here in Malaysian tropical environment where its about 35 deg C and 80%RH ambient, an open freezer door ( even for a minute) can bring in enormous moisture ( due to vapour pressure difference)

I completed a job for a multi-national Eurpoean food company located here (better not mention names). At design stage , I advised them to have a little ante-room ( buffer room) at 5 deg C . ( the freezer was designed for -20 deg C to store frozen tomato). They refused and asked me for an alternative. Told them to keep a close watch on door opening period and frequency.

Went back 1 month after commissioning and sure enough, the blower was iced up and within days would have caused the motor to burn on extremely high static pressure. Manually defrosted the unit and stood away to observe operations. Sure enough, two operatives come by , not wearing any freezer jackets and gloves , one opens the door wide open and the the other quickly runs in and grabs couple of cartons, comes out , places them on a pallet, goes back inside again. This happens for about 10 times unitil the pallet is full. All this time , the door is open ( and the plastic strip curtains are to one side) and you can see the power of the VP difference - heavy fog!!. I then went near and asked them about the door management rules. They answered - "too cold,what do you expect us to do- too troublesome to wear the special attire provided- if the door is kept open, the temperature is not so cold anymore" What more can you say!!!
The issue was finally solved with good door management and some improved discipline!