Saving fuel and engine wear while keeping legal in no-idle zones
One problem with idling to heat or cool your cab is that your truck’s diesel has no throttle. When idling, the engine is grabbing better than 20 gallons of air per second and shooting in a tiny fraction (1/3600) of a gallon of fuel. This means most of the energy produced is being wasted through the exhaust pipe rather than heating your cab.
Idling, however, does keep your batteries charged and the engine warm. One way to accomplish all this without idling is to substitute a much smaller diesel. That’s the idea behind a genset or diesel APU. By sizing the engine to the job to be done, each cylinder full of air gets plenty of fuel to heat it up, and the engine runs much more efficiently.
Other methods of making idling unnecessary include direct-fired cab or engine heaters and even one system that uses the heat from the engine to heat the cab.
Diesel APUs and Gensets
These systems use an engine to generate both household current (120-volt AC) and 14-volt DC. The AC current is used to supply the trucker’s appliances in the cab and sometimes provides air-conditioning and heat. An air-conditioner compressor may be driven directly by the engine, and the engine heat sometimes heats the cab. The DC charges the batteries. The cooling system often is connected into the diesel’s cooling system so heat from the engine can keep it warm, though APUs and gensets also have their own radiators.
Diesel fuel-fired cab air or coolant heaters
These units combine a small heat exchanger and a sophisticated diesel fuel burner. The fuel is burned in a combustion chamber inside the metal heat exchanger and ignited with a small glow plug.
Direct cab-air heaters blow cab air around the heat exchanger and into the cab or sleeper.