Cold starts can cause accelerated engine wear, which in the long term causes damage to components and will shorten the engine life. An engine preheater warms up an engine and keeps it at a stable (starting) temperature when it is not running. This ensures easier and faster engine starts, which is better for your engine because it reduces engine wear. In addition, preheated engines consume less fuel and therefore emit less harmful substances, which is better for the environment.
Next to these benefits, in some cases direct engine starts are essential, for example for emergency generator sets for hospitals, sprinklers systems, emergency vehicles, etc. Preheating the engine ensures that it is always ready to start. Failure to install a preheater can cause the generator not to start instantly when called upon, which can have disastrous consequences.