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View Full Version : Why did Compressor quit due to cold temp



Titerope
01-07-2014, 08:58 AM
The outdoor unit for our walkin cooler quit last night in -5 degree temps. Called the technician first thing this morning and they had already had about 15 calls for the same issue. What causes this? What can I do to prevent it? Is there anything I can do to fix it?

Thanks

jimvgjr
01-07-2014, 09:50 AM
In real simple terms, the refrigerant migrates to the coldest part of your refrigeration system, right now that is your outdoor condensing unit. It makes a real challenge to get the refrigerant flowing through out the system before the refrigeration system will cycle off on a Low Pressure Alarm.

During these extreme cold temperatures there are several things you can do to assist the system and prevent these nuisance alarms. One thing you can do is cover a portion (perhaps 50%- be careful to not completely block off the flow of air) of your condenser surface with cardboard to restrict the airflow across the coil. this will help increase the Condensing Pressure and get the refrigerant to leave the condenser and flow to the Walk In cooler where it is needed.

Your contractor has several options to help prevent nuisance alarms:



Install dedicated fan cycle control on each condenser fan that will hold this fan off until you build enough head/condensing pressure to force the refrigerant out of the condenser.

They can also install a Low Pressure Bypass Timer that allows additional time for the system to get the refrigerant flowing through the system before tripping off on the alarm.

Another option is to install a 3 Way Head Master, or Head Pressure Control Valve, that will bypass the Hot Discharge Refrigerant Gas directly into the refrigerant receiver, while backing up liquid refrigerant into the condenser and reduce the condenser surface area. These will require an added refrigerant charge to the system could require an over sized refrigerant receiver to be installed as well.



We have a number of additional options for really cold climates that include wrapping refrigerant receiver with heat tape and insulation, variable speed control on the condenser fans, and more.

For many people it is hard to believe that one of the biggest design challenges for a refrigeration equipment manufacturer is ambient related, with extreme cold ambient a bigger challenge than extreme warm weather poses.

Hope this helps somewhat and you are able to get the system reset and online quickly.

Good Luck,

Jim

jimvgjr@prorefrigeration.com
www.prochiller.com

Titerope
01-07-2014, 10:22 AM
Thanks Jim. Useful information indeed. I was hoping to get this thing running without having to call a technician but I can't seem to find a way to reset that low pressure alarm. Can I somehow adjust that low setting to get it flowing again or am I better off waiting for a trained hand. Thanks

jimvgjr
01-07-2014, 05:25 PM
Thanks Jim. Useful information indeed. I was hoping to get this thing running without having to call a technician but I can't seem to find a way to reset that low pressure alarm. Can I somehow adjust that low setting to get it flowing again or am I better off waiting for a trained hand. Thanks

sorry for late reply, probably best to wait for your refrigeration guy to show up, may be something else going on. Hoping by now you've gotten the system up and running, we have a great contractor we work with in Asheville if you still need some help. Shoot me an email and I can forward his information.

Jim

jimvgjr@prorefrigeration.com