Specially designed for very cold climates but not available everywhere as optional equipment, there is a new, independent heater unit for the 2 CV, which will function even when the car is stationary: air taken from outside the car passes through a heat exchanger which heats it to a predetermined temperature before it is passed into the interior of the car.
In this hear exchanger, the combustion circuit is independent af the heater flow and it operates at a relatively lower pressure which precludes any possibility of contamination of the heated air by combustion gases. The petrol used for combustion is the same as that used for the car and is taken from the car’s petrol tank. It flows through a diaphram type regulator which controls the petro/air mixture. This is in preference ta a constant level float chamber type carburettor as this regulator will operate in any position. The mixture is sucked into the combustion circuit and burnt in a burner, ignited by a high tension spark produced by a special coil-contact breaker system which regulates the re-ignition down to temperatures of – 30° C. The hot gases circulate in the internal part af the heat exchanger before being sucked away. At the same time, cold air taken from the outside through a special air intake under the wing of the car, is blown through the exterior partion of the exchanger where it is heated by the combustion circuit. It then passes into the car ( see diagram).
An automatic regulator keeps the temperature constant: a bi-metal contact system switches the combustion on and off. The two circuits of the exchanger are operated by blowers driven by the same motor, the whole unit being dynamically balanced toeliminate all vibration. There is also a series of automatic safety devices which prevent any possibility of danger from the unit: 1/ Petrol will only flow to the regulator when the car ignition is switched on and the unit control knob is in the ”on” position. The unit stops functioning when the ignition is switched off. Therefore there is no danger of petrol flooding. 2/ It is impossible for the temperature of the air blown into the car ta exceed a predetermined level. 3/ When the unit is turned off, the blower continues to turn for a while so as to cool the exchanger.
Lähde: Le DOUBLE CHEVRON N°3 (1965)