Hey guys, First time posting but I have been using this forum for about a year now to help me with improving my career.
I have a question about an open face cooler. It is a Howard McCray SC-D32E-8-LS. My boss from work has an apple farm and he asked me to take a look at it before he opened for the season. He said he bought it used and
when he plugged it in he found that the temp in the cooler with the curtains closed would drop to 28*F. So I stopped by to take a look and the cooler was infact in about 5 minutes after being turned on pulls right down to 28*F
The ambient in the room was 72*F. The cooler was completely empty. Not being that framiliar with the operation of an open faced cooler I started looking over the unit. 128 OZ of 404a. I hooked up my guages and it was running about 55P.S.I. suction with a superheat of about 40*F. The discharge was 210 P.S.I. The subcooling was at 7*F. When I open the curtains the temp hovers around 38*F with the same suction pressure and 30*F super heat. I'm just wondering that if the cooler needs to be loaded for it to work properly.
My boss doesn't want to have to leave the curtains open all night and waste energy. Any help or insight into the open face cooler world would be greatly appreciated.
Your pressures look fine. Open face boxes tend to cool down within a few minutes, and will cycle on and off more than a reach-in. Find out where the thermostat sensing bulb is located; is it in the evaporator return air, supply air, or inside of the evaporator coil? What is thermostat setpoint? Does it have a digital controller?
Open coolers do tend to have large temperature swings when they are empty. Part of this is because the temperature controls are often located in the discharge air stream. That being said I have run into several units with curtains you can pull down at night that tend to run a bit cooler when the curtains are closed at night and it can be a balancing act to get the setting just right such that it is not too warm during the day, but isn't freezing things at night. One good way to check things is to set several jugs of water in the cooler to simulate product load. As long as your water isn't showing signs of freezing up, you'll likely be all right.