Image Number 17 for United States Patent #5878950.
A supplementary vehicle heater is provided which includes a burner, a heat exchanger, a coolant conduit connected to the heat exchanger and a coolant pump connected to the conduit. There are controls which are operatively connected to the burner and the coolant pump which operate the heater in a first mode when the engine is stopped to preheat the engine or keep the engine warm. The controls operate the heater in a second mode when the engine is running to improve heating of vehicle interior. Preferably the controls include automatic controls which engine coolant temperature. The controls cause the burner and pump to function when the engine is running and the coolant temperature is below preset temperature.