How cold weather affects outdoor refrigeration units.

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Winter in Chicago can be tough on outdoor commercial refrigeration equipment. Refrigeration compressor units that are installed outdoors must have cold weather controls to operate properly and maintain proper temperature in the cooler or freezer during the cold winter season.

When it gets cold out the refrigerant pressures will drop too low due to the cold air passing through the condenser coil. When this happens the space being conditioned will no longer maintain the proper temperature. A compressor unit without proper low ambient temperature controls may sit idle and not even turn on due to low pressure.  Don’t worry if this happens to you – Northeast Cooling can help keep your equipment running well this winter.

One way to maintain proper head pressure on an outdoor unit in cold weather is by using a fan cycling control. This control reads the head pressure of the system by connecting it to the high pressure refrigerant line. It makes and breaks power to the condenser fan motor to maintain a certain pressure.

Here is an example setting for R22 gas: Fan cycle setting 260# of pressure turns fan on.  230# of pressure turns fan off.

By keeping the head pressure above 200# the fan cycle control avoids a warm refrigeration unit during cold weather. This works well in most situations,but not all. A fan cycle control will not work well in sub zero windy weather. When it is very cold and windy out the pressures can still drop too low even if the condenser fan remains off. Extremely cold air can cause the refrigerant pressure to drop too low simply by blowing through the condenser coil.

Another way to maintain proper pressures in cold weather is by using a bypass valve. This valve lets refrigerant bypass the condenser coil when the pressures drop below a certain level. The dome on the bypass valve is charged with nitrogen. This gas does not change pressure based on temperature. That is why it is used to control the opening and closing of the bypass valve. When it is cold and the bypass valve senses a head pressure drop it lets the gas bypass going through the condenser coil and diverts it straight into the system liquid line. This set up works better for areas that are extremely cold and windy all winter.

When it gets cold this winter monitor your refrigeration equipment temperature, especially if the compressor unit is outdoors. If you notice your box warming up on cold days chances are it doesn’t have proper winter controls. This can end up damaging the compressor and other components within the system.

Northeast Cooling specializes in all types of commercial refrigeration and can help keep your equipment running well this winter.

Contact us for a quote on winter controlls to protect your equipment and your product!

  • Michael R

    I’m having multiple problems this year with some of the WI CLRS. I’m finding warm box temps and low pressures. My boss is telling me to add ref and run head up above 200. Sometimes like yesterday it was 16F out and wind is blowing into condenser r404. I add 25 lbs and pressure still wouldn’t go up. The thing is I don’t feel the headmaster even bypassing. Would installing fan cycle controls solve this and what are the settings for different refs and outdoor temps. Thanks for your article and help is appreciated

    Michael R
    VA.

    • Mitch Byrne

      If you added 25# of extra gas the system is probably overcharged now. If you don’t feel bypass valve bypassing condenser its probably bad. In otherwords, if it’s cold out & you still feel heat on the line feeding condenser then the valve is not bypassing properly. In cold weather the valve should be diverting the hot gas straight to the reciever most of the time. A fan cycle control will work OK except in extreme cold & windy conditions like sub zeros & windy. Fan cycle control would work fine 95+% of the time. Below are approximate settings for fan cycle per gas.

      404A 270# fan cut in 230# fan cut out
      R134A 170# fan cut in 130# fan cut out
      R22 270# fan cut in 230# fan cut out

      I emailed you. Feel free to call me to further discuss this charge & pressure issue.

    • Mitch Byrne

      If you added 25# of extra gas the system is probably overcharged now. If you don’t feel bypass valve bypassing condenser its probably bad. In otherwords, if it’s cold out & you still feel heat on the line feeding condenser then the valve is not bypassing properly. In cold weather the valve should be diverting the hot gas straight to the reciever most of the time. A fan cycle control will work OK except in extreme cold & windy conditions like sub zeros & windy. Fan cycle control would work fine 95+% of the time. Below are approximate settings for fan cycle per gas.

      404A 270# fan cut in 230# fan cut out
      R134A 170# fan cut in 130# fan cut out
      R22 270# fan cut in 230# fan cut out

      I emailed you. Feel free to call me to further discuss this charge & pressure issue.

    • Jeff G

      I’m having same issue. I am on a drilling rig offshore south of Louisiana. We are having an Arctic Blast push through with temps in the 20s and wind chills of single digits. Try this , block off your coils with card board or anything you can find and watch your pressures, I’d be willing to bet anything that your head is going to rise. Therefore the pressure controlled fan would be a solid win for this situation and probably the most cost effective.
      Jeff G.
      Gulf of Mexico

      • RefrigerationForAll

        If you are going to install a fan cycle switch you need to cut the little sealed nipple on the headmaster valve and then soap it and make sure it isn’t leaking. If it is leaking then remove the valve all together. We commonly do this and replace with a fan cycle switch for customers not interested in spending the money on a new headmaster valve.

  • Thanks for checking out my blog fellas! If you added 25# of extra gas it’s probably overcharged. If
    you don’t feel bypass valve bypassing condenser its probably bad. Fan
    cycle control will work OK except in extreme cold & windy conditions
    like sub zeros & windy. Fan cycle control would work fine 95+% of
    the time. Below are approximate settings for fan cycle per gas.

    404A 270# fan cut in 230# fan cut out
    R134A 170# fan cut in 130# fan cut out
    R22 270# fan cut in 230# fan cut out