Aggressive governmental efforts to reduce harmful greenhouse gas emissions have focused on trucks in a growing number of states, resulting in new and more stringent anti-idling regulations. At the same time, on-highway truck fleets continue to face the need to provide driver comfort and convenience in an effort to help attract and retain drivers, and to reduce fuel consumption due to rising prices.

“As more jurisdictions approve anti-idling measures in an effort to reduce air pollution, and as diesel prices continue to climb, many trucking companies believe they have little choice but to equip their trucks with devices that restrict engine idling,” says Eldon Willis, vice president of sales and marketing for Auxiliary Power Dynamics. “But when fleets install such devices and offer little or nothing to help their drivers work comfortably, such measures may encourage their best drivers to leave and join other companies.”

To meet these challenges, an increasing number of fleets have begun specifying on-board auxiliary systems for use during driver rest and off-duty periods. The systems now offered by truck OEMs as original equipment, and from a variety of manufacturers for new vehicle and aftermarket installation, are exceptionally efficient in providing cab heating and air conditioning, truck battery charging, accessory power and engine block heating.

Fleets have a variety of choices for auxiliary systems, including auxiliary cab and sleeper heaters, some with engine heating capability, and full auxiliary power units (APUs) that offer heating, cooling, accessory power, battery charging and engine heat. Both can assist fleets with providing cab comfort and reducing fuel consumption. But the amount of savings companies can realize depends on how well the units are specified.

For APUs, says Willis, there are several considerations for fleet managers to take into account and find the model that will do the best job. Watson offers these tips when choosing an APU:

1. Understand your drivers’ needs and the conditions under which they operate. Determine when, where, why, and for how long your drivers idle their truck engines by holding discussions and taking surveys, and verify what you learn by looking at maintenance reports or driver and engine logs.
2. Keep in mind that cooling capacity on APUs can vary substantially among different units. APU manufacturers usually measure capacity in terms of the number of British Thermal Units (BTU). As a reference, a truck’s HVAC system generally delivers 30,000 BTU or more of cooling capacity.
3. Some APUs are integrated into the truck’s HVAC system using existing controls and vents to direct air flow. Integrated units can be desirable for larger cabs and sleepers or for sleepers with dual bunks. Other units use their own vents to provide heating and cooling.
4. Many non-integrated APUs require space inside the sleeper in order to fit their ductwork, AC systems or other components. Integrated APUs are usually mounted outside the sleeper.
5. An APU with a heavy-duty alternator can better handle the higher electrical loads associated with personal devices common in a larger sleeper. With a heavy-duty alternator, the APU will be less likely to fail, and it will recharge the truck batteries faster and protect the truck’s electrical components.
6. APU engines are offered with one, two or three cylinders. Typically, the more cylinders, the better the APU will perform because the engine operates at a lower RPM. More cylinders also means the APU is quieter.
7. Investigate how many potentially battery-draining devices are on the truck and how frequently drivers use them. You should also understand the cumulative effect of all those devices drawing power from the APU. This is particularly important to know if you’re considering an APU that uses a deep-cycle battery to power the truck’s HVAC system and hotel loads.
8. Diesel-powered APUs can be integrated with optional 110-volt AC inverters and deep-cycle batteries to help better manage electrical loads. The optional inverter allows drivers to run appliances that are widely available and less expensive than appliances designed to operate on 12-volt DC current.

Choosing auxiliary heaters

Properly chosen auxiliary heaters for truck cabs and sleepers can provide fleets that operate in colder climates with considerable savings in fuel and engine maintenance costs, while offering their drivers a more comfortable environment. Brian Curliss, product manager for Teleflex Power Systems, offers the following ten tips for effectively selecting the best product to meet a fleet’s needs:

1. Fuel-fired auxiliary heaters come in two types: coolant and air. A diesel-fired coolant heater circulates truck engine coolant through a heat exchanger. Coolant heaters reduce wear and tear on truck engines and reduce the need for service calls to warm up frozen engine blocks. A heavy-duty coolant heater burns about a quart and a half per hour, far less fuel than the average gallon per hour that an idling truck engine burns. Diesel-fired air heaters draw air over a heat exchanger. They can preheat or provide supplemental heat to the cab or sleeper, but not the engine block. Depending on their capacity, air heaters burn anywhere from one half to one cup of fuel per hour.
2. Consider the heater’s capacity or heat output. As a rule of thumb, maintaining a comfortable inside temperature when the outside temperature is 32 degrees F requires 20 BTU for every cubic foot of space. That means an 80-in. double bunk sleeper with a volume of 320 cu. ft. requires a heater with 6,400 BTU.
3. Like installing insulation in the roof and walls to winterize a home, installing thermal curtains and extra insulation in the cab and sleeper keeps the heat in and the cold out. It also reduces the amount of time it takes for the heater to warm things up.
4. The heater’s capacity and the outside temperature determine how long it will take the heater to warm things up. If you need a heater that can heat things up quickly, you should consider a unit with a high BTU rating, but keep in mind the higher the rating, the more fuel the heater will burn.
5. Heavy-duty coolant heaters require open frame rail space, so they can’t be mounted under the hood. Air heaters and their ductwork are mounted inside the cab or sleeper to heat and circulate air for driver comfort. Optional mounting hardware makes it easier to attach the heater to the floor of some truck cabs.
6. Generally, heaters have three types of controls: manual, automatic (a timer), or full temperature. With a manual controller, the driver must start and stop the heater and control the power of the heater. With a timer, the driver can set the heater to start and stop automatically. This allows for the cab to be warmed up and the windows to be defrosted or the engine to be warmed up before the driver even opens the door or turns the key at the start of the shift. Full temperature control is exclusive to air heaters and gives the driver the greatest degree of control over the cab or sleeper environment. The driver can control the heater manually or set it to operate automatically. Full temperature control also allows the driver to control the heater’s fan speed and regulate the temperature more accurately.
7. Before selecting a heater, determine how often and how long your drivers idle their trucks to heat cabs or sleepers. And remember that even for those drivers or equipment operators who work in extreme cold, but don’t spend the night in their vehicles, an auxiliary heater could improve their working environment.
8. Capacity, length of time in use, and cost of fuel determine how much money your company can save on fuel costs with an auxiliary heater. For example, a heater with a capacity of 6,800 BTU more than adequately heats most truck sleepers and burns about one cup of fuel per hour, a 97 percent savings over the average gallon of fuel an idling truck engine burns. If your driver uses the heater eight hours each day for five months each year, and your fuel costs are $3 per gallon, your company will save about $2,300 annually.
9. It takes a trained technician about four hours to install an air heater and about six hours to install a coolant heater. Most heaters require a simple annual system inspection to check connections and ensure the units and their components are clean and free of build-ups.
10. Anti-idling regulations vary in the U.S. and Canada. In many places, idling truck engines can carry huge fines and penalties. The American Transportation Research Institute publishes a list of idling regulations in the U.S. at www.atri-online.org. For more information about idling restrictions in Canada, visit the Natural Resources Canada FleetSmart Web site at http://oee.nrcan.gc.ca/transportation/fleetsmart.cfm.