Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login

Posted: 11/3/2009 8:16:36 AM EST
I got a little problem that I was hoping you guys could help me with..

I have a walk-in cooler at work that is about 20X20. About six months ago the cooling unit shit the bed so I bought a new unit. Ever since I got the new unit it is VERY humid in the cooler.
So humid that there is mold growing on the walls and all the cardboard boxes are moist and tearing easily..
THis was never a problem with the old cooling unit.

The only difference that I can tell is that the fan on the new unit runs ALL THE TIME.. Where as on the old unit the fan only ran when the compressor was running.
The guy that did the install said that the fan was not making all the moisture..


What does the HIVE say???

Thanks
Link Posted: 11/3/2009 9:09:34 AM EST
My guess is the new refrigeration unit is too big. What happens is the oversize unit pulls the temp down too quickly and shuts off, not allowing time to condense the moisture on the evaporator coil. A hot gas bypass could be installed to limit your refrigeration capacity, this would be the correct way of doing it. The cheap and not so good way would be to under charge the system refrigerant, it would work but would raise the suction temp and cause the compressor to run hot.
Link Posted: 11/3/2009 10:37:42 AM EST
Is that somthing I can install or best left to the refridgeration guy??
Any idea of a price for somthing liie that??

Thanks
Link Posted: 11/4/2009 3:52:51 AM EST
anyone else I got to get this thing fixed..
Link Posted: 11/4/2009 4:15:28 AM EST
dont know enough about coolers but have dealt with simaler problems witj humidity
you could ask the tech about running the system off a indoor humidistat
that would control the compressor on off cycle
Link Posted: 11/4/2009 7:21:29 AM EST
Originally Posted By clutchsmoke:
My guess is the new refrigeration unit is too big. What happens is the oversize unit pulls the temp down too quickly and shuts off, not allowing time to condense the moisture on the evaporator coil. A hot gas bypass could be installed to limit your refrigeration capacity, this would be the correct way of doing it. The cheap and not so good way would be to under charge the system refrigerant, it would work but would raise the suction temp and cause the compressor to run hot.
This......somebody had a system on hand they wanted to get rid of and sold it to you....your system is to big for the use on hand I've had seen this problem before brings the temp. down just fine but the area feels like a cave...whoever sold you this system needs to come back and make it right..either way with a hotgas or undercharge will short'n the life of your compressor...the ol saying remains true in A/C and refrigeration buy once cry once....

Link Posted: 11/4/2009 7:27:04 AM EST
Link Posted: 11/4/2009 7:29:11 AM EST
Link Posted: 11/4/2009 1:42:48 PM EST
In commercial refrigeration coolers, the fans are supposed to run continuously. The evaporator temperature in a 35F cooler is 25F and being below freezing will accumulate frost. When the thermostat is satisfied the unit pumps down, and shuts the compressor off, but with the fans continuing to run. The 35 degree air blowing across the evap coils defrosts them, and is called "off cycle defrost system". Freezers shut the fans off for the defrost cycle usually using electric elements to melt the ice/frost. The fans are off to keep from blowing the heat around the freezer and blowing water droplets on the floor to freeze and make an ice skating rink. Like earlier mentioned oversized equipment doesn't allow for long enough run times to completely remove the humidity from the air. Hot gas bypass systems can be costly and dangerous to compressors if not set up correctly, and are big energy wasters as the compressor running at full amp draw, but you are bypassing hot gas to the evaporator to keep the suction temp up and reducing system capacity. In the long run you are better off to get correctly sized equipment, and sell off the oversized stuff. I do commercial refrigeration load calculations, and equipment selections, for a living and can help you out with the sizing if you get me some basic information. E-mail me Skeeters65 and I can figure it out for you.
Link Posted: 11/4/2009 5:48:09 PM EST
A cheap / dirty / temporary / power hog fix would be to put a 1500 watt milk house heater inside the cooler. Yes a heater in the cooler, it would provide a false load and cause the condensing unit to run longer, thus removing moisture. Like I said, it would work but it would be a power hog.
Link Posted: 11/4/2009 5:56:26 PM EST
Check the drain. If the bottom of the evap coil is full of water then its just moving humid air around.
You should be able from behind stick your finger in the drain pan. No water should be in there.
If so take a shop vac to the pvc and suck out the plugged drain line.
Link Posted: 11/4/2009 6:23:26 PM EST
In addition to the abovementioned oversized compressor, check to make sure there is no air leakage into the space. If ambient air gets inside, it brings moisture with it.
Top Top