How many degrees of temperature difference is the smallest for diesel heater?

the temperature difference of 4 degrees for diesel heater is the smallest. The temperature of four-hole parking diesel heater should be adjusted to 4 degrees. The firewood heating gas is a kind of heating equipment installed on the vehicle. The fuel used for the firewood heating gas is diesel. Controlling the temperature at 4 degrees can keep the comfortable temperature of the cab, and the temperature difference is minimal. The four-hole parking diesel heater is good, and the heating speed is much faster than that of the single-port one.