[Balding_Eagle]

That’s why someone who knew what he was doing would have installed fuel heaters in that bus.

Never heard of fuel heaters for diesel vehicles or equipment.

How do do keep the lines from the tank to the engine warm? Heat tape?

[Clinging Bitterly]

Diesel fuel heaters have been around as long as Diesel fuel. Usually not necessary in most of the US, but they come in all forms - built into fuel filters, wrapped around lines, or even heating whole tanks. Most Diesel engines circulate a large volume of fuel through the warm engine (or at least it's fuel injection pump) and back to the tank, so they only need a small amount of prewarmed fuel to get them started. In those cases a regular plug in block heater is usually enough for all but arctic conditions. Beyond that, the heating methods used and the reasons for having them can become quite complex. Some extreme climate engines are never shut down, even for routine maintenance such as oil changes, because restarting them would cost more time & energy than just leaving them idling for a shift or even a week or a month.