Cool temps & warm walk-ins
If you notice your walk-in or reach-in cooler seems oddly warm when the weather is cold, it could be suffering from a condition known as refrigerant stacking. But why does this problem only show up in the cold weather? And what should you do about it?
The refrigeration cycle
Air conditioners, dehumidifiers, ice machines, coolers and chillers all utilize the refrigeration cycle for cooling indoor spaces. Though these systems utilize different types of refrigerant, the basic premise is the same across the board.
There are two main parts to a refrigeration system: the evaporator and the condenser. Refrigerant flows between the evaporator and condenser, circulating throughout the system. The refrigerant essentially absorbs heat from inside and releases it at the condenser. The cooling aspect occurs when the compressor (a part within the condenser) forces a phase change within the refrigerant.
If you’ve ever used a can of air to clean out a computer keyboard or other hard-to-reach spaces, you might have noticed that the can gets cold as you press the button that releases the air. This is a simplified example of how the refrigeration cycle works to cool. In the can, the ”air” is actually a mixture of gases compressed into a liquid state and functions the same as a refrigerant in a cooling system. As it is rapidly released from the can, it changes back into a gas. Changes in state require energy, which the refrigerant absorbs as heat from its surroundings, making the can turn cold.
Apart from compressing the refrigerant, the compressor more or less acts as a pump, circulating the refrigerant throughout the system. There are a few other key parts that assist this operation but those are the basics. One other key characteristic of refrigerant is that it will naturally migrate to the coldest part of the system. This is where refrigerant stacking can come into play.
What is refrigerant stacking?
Refrigerant stacking occurs when coolant builds up in the outdoor condenser instead of circulating through the system like it should during normal operation. If your walk-in cooler has an outdoor condenser, you might see this issue appear in colder weather when the ambient outdoor air temperature is low. In milder daytime temperatures, overnight lows might still cause an issue for the system. If this happens, you’ll have a warm walk-in in the morning that seems to get better throughout the day.
Refrigerant stacking can be caused by a number of things. You might just have a dirty condenser that can be taken care of quickly or your cooler might have something bigger going on, such as low refrigerant charge. Either way, it's time to have a technician out to take a look. If you continue to run the cooler while refrigerant is stacking in the condenser, it will not be able to cool itself and can cause even more damage! A buildup of refrigerant in the condenser will block the condenser’s ability to remove the heat it absorbs from indoors. It essentially makes the condenser “smaller” and less effective.
Under normal operation, the last part of the system to receive cooling is the compressor. We mentioned above that the compressor is responsible for circulating the refrigerant throughout the system. Unfortunately, this is an expensive part to replace when it fails. If you continue to run your cooler when it’s not functioning correctly, there’s a good chance that the compressor will overheat and ultimately fail. Any signs of refrigerant stacking should be looked at immediately to find out the root cause.
If your chiller has a headmaster valve, some refrigerant stacking is normal during cold weather. This type of setup will have more refrigerant within the system and the headmaster valve will act as a pressure regulator and will modulate as needed. If the headmaster valve is working correctly, you won’t notice any ill effects from refrigerant stacking that happens during colder weather. If you do notice any problems with your chiller, it’s time to call a professional and have that valve examined.
Don’t forget to schedule preventative maintenance
We recommend walk-in and reach-in coolers be professionally serviced every six months to optimal performance. We want to catch any small problems before they have the chance to turn into big repair bills. But if you notice your cooler getting a little too warm when the weather is cold, give us a call.
Austin, Texas Location
Tri-Point Refrigeration, Inc
118 Iron Road Suite 100,
Hutto, Texas 78634
(512) 651-4565
Lubbock, Texas Location
Tri-Point Refrigeration, Inc
13805 Avenue P Unit B
Lubbock, Texas 79423
(806) 686-0050