Trailer Report: Running Reefers Right

December 2010, - Feature

by Tom Berg, Senior Editor, Senior Contributing Editor - Also by this author

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People who operate refrigerated trailers know a lot about their businesses, but even the most experienced would tell you that they don't know it all.
The newer the reefer, the more efficient its engine, compressor and other components. (Photo by Tom Berg)
The newer the reefer, the more efficient its engine, compressor and other components. (Photo by Tom Berg)
To them, and maybe more for the less experienced among truckers who haul temperature-controlled freight, makers of reefer units freely offer advice. They did so last summer at the Truckload Carriers Association Refrigerated Division's annual meeting near Bend, Ore.

In separate sessions, representatives of Carrier Transicold and Thermo King listed the capabilities of their products, whose microprocessor controls are amazingly adept at dealing with a wide variety of products, assuming drivers are trained on how to set them for maximum efficiency.

Drawing on their contacts with many trucking customers, the reps also discussed operating considerations and how they affect expenses. Their presentations were enhanced by comments and questions from those in the audience. Among the items discussed:

Running modes

Stop-start vs. continuous running: These determine how much the reefer unit's engine runs, and therefore how much fuel is burned and the amount of maintenance on unit components. They also control how steady the temperatures of the perishables in the trailer are. Ambient temperatures and the trailer's insulation value, along with its age and condition, also affect how much the unit must run.

Temperature swings of 5 or 10 degrees over and under the set point are tolerable for many commodities. But some cargoes require steady temps, which require continuous running. And some shippers demand continuous running even though their products don't need it. Acceptable bands of temperatures should be negotiated with each shipper prior to signing a contract or picking up a load, so drivers can correctly set the unit's controls to satisfy the shipper and save as much operating money as possible.

If a shipper demands continuous running, a trucking operation should ask itself: Does the freight rate reflect the relatively high fuel and maintenance costs for the reefer unit? Or does the trucker comply with his wishes for barely adequate compensation? As capacity is becoming constrained and shippers have less clout, the trucker can request higher compensation and probably get it.

Larger carriers have the resources and expertise to track each customer's shipments, then determine if rates are adequate. And they can use their knowledge of products to determine if a requested temp is realistic. These factors are then built into rates for each customer. Of course, any final figures are negotiable, but the knowledgeable carrier enters negotiations better prepared than one who hasn't done his homework. Smaller carriers can build their knowledge with the help of their reefer suppliers and use of the correct operating software.

Products such as beverages, paint, canned goods and candy are safe within wide temperature ranges, even if shippers want narrower ranges. A wider range might save 50 percent in fuel. Learn what the safe temperature ranges are for every commodity hauled and try to reason with customers about settings.

It's a good idea to document fuel use and running times for every customer and every product, and have the information handy when negotiating rates.

Trailer use and care

* Drop-and-hook operations are often necessary to minimize driver waiting times, but trucking companies lose control of their trailers when they're left at customers' docks and yards. Customers can do almost anything with trailers if they aren't tracked and reefer running isn't monitored. Telemetry allows remote, real-time monitoring, but careful manual recording of running hours can also tell tales of possible abuse.

* Don't run a unit if the doors are open, whether making deliveries or while it's parked somewhere. This is an obvious waste of energy, but drivers and customers might do it if it's convenient and they're not told otherwise. Door switches can cut off the unit when doors are opened. Some customers may demand that reefers run while trailers are at their docks; if so, see that the engine runs at lower rpm to save fuel.

* Use the highest insulation value possible while allowing sufficient cube in the trailer. Insulating values are expressed by UA numbers, and the lower, the better. A low UA might be awarded to a trailer with 4 inches of insulation in the roof, floor and walls, and might allow a reefer unit to use only half the fuel of a trailer with a high UA number because of only 1.5 inches of foam in the walls and 3 inches in the floor and roof. But the low-UA trailer will have 7 percent less volume and might weigh an extra 250 pounds, causing the tractor to burn some extra fuel to pull it.

* Repair tears and punctures in trailer skin as soon as possible. Breaches in the skin allow conditioned air to escape and moisture to contaminate insulation, further worsening performance. The longer the damage goes unfixed, the more costly the repair will be.

* Know what a reefer's sophisticated controls can do and train drivers to get the most from them. Complexity of controls can be masked by showing drivers how to use easy-to-understand settings. Modern microprocessors have scores of possible settings, not only by temperature and temperature range but also by commodity (for instance, fresh fish, potatoes, strawberries) and customer name (ABC Produce, which usually ships lettuce).

* Run modern reefers because they'll be more efficient than older units. Engines on newer units will also emit fewer pollutants, which keeps California authorities happy. One fleet manager said his company runs trailers for 10 years and switches units every five years, so a unit is never more than five years old.

* Electric "standby" power saves fuel, and is becoming necessary in California. But of course plug-ins are required wherever the trailer will be spotted. This will almost always be at docks, and the reefer unit must be able to run on the voltage that's available. Older units were set up for 220/240 volts, but current industry practice favors 440/480 volts. Yes, those voltages are in ranges, as with 110/120-volt home power; but sometimes the power must be exact, like 3-phase, 460-volt. Know what the voltage is where trailers will go - or tell customers what it should be - so all equipment is compatible. Partnerships with customers are the best way to ensure this.

The future will bring all-electric reefers with no engines. And that's another story.

From the December 2010 issue of Heavy Duty Trucking magazine.


  1. 1. haller [ March 18, 2014 @ 03:35PM ]

    What does it cost to run a refer at 37 degrees for 12 hours if the product was loaded at 37 degrees?

  2. 2. Pawan [ April 04, 2014 @ 06:44PM ]

    Hi can u tell me plazz which model reefer and how much

  3. 3. Ruben Izurieta [ August 02, 2015 @ 10:34PM ]

    a load was set at
    -5 first compartment
    and 34 second compartment
    unit arrived to destination at
    18 and 48
    this can be consider out of temp

  4. 4. Eliza Cranston [ December 03, 2015 @ 09:24AM ]

    Thank you for the advice on running refrigerated trailers. I ship refrigerated products pretty long distances and I want to make sure that everything is running smoothly. You say that "temperature swings of 5 or 10 degrees over and under the set point are tolerable for many commodities." Could you explain for which commodities it is not tolerable to have temperature swings and how to control this?

  5. 5. amit [ December 10, 2015 @ 01:49PM ]

    how many boxes of potatoes are you able to get in a 53 foot trailer?

  6. 6. haller [ December 29, 2015 @ 08:23PM ]

    my guess would be around 1080, based on my experience with cabbage.

  7. 7. Dennis Klitzka [ January 28, 2016 @ 11:22AM ]

    How long does it take to condition a refer truck to 30 degrees?

  8. 8. Buck [ March 21, 2016 @ 03:28AM ]

    I bought two 20ft carrier diesel with electrict stand by only problem is there 3 phase and my residrntial property died not have that option can I change the 3 phase electrict motor out to make it 110 volts? If do what motor would I need? These are 2000 models one is 230vokts and one is 250 volts one is 4 prong and one is 3 prong plugs please help

  9. 9. Buck [ March 21, 2016 @ 03:29AM ]

    Also how cold with these boxes get and how high 50%?

  10. 10. Leonard Matthews [ July 06, 2016 @ 09:48AM ]

    I bought a Blue Bell reefer truck and I need to know if the reefer has a adjustable thermostat on it.

  11. 11. Ralph Perrott [ November 20, 2017 @ 01:30PM ]

    Does the truck engine have to run while the reefer is being unloaded at a dock ?


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