That is correct – there is a thermostatic plug in one of the housing’s three ports which is closed when cold and opens the circuit when warm. The power heating element is inside the black plastic disc, with its contacts to one side.

I didn’t use the thermostat because I wanted to use the heater to get the fuel as hot a s possible, but I suspect the thermostat was in a circuit through the control side of a relay and not in a direct circuit to the heating element. The element draws about 10A.

I replaced the heater with a coolant based fuel heat exchanger for heating the vegoil fuel, but later had problems with SVO use and now stick to diesel.

Nick.