The adjustable electronic thermostat “XT51” is projected to commutate an exchange electric contact when the temperature reaches a value settled by the user. A bicolour led signals the commutation of the electric contact. The adjustment of the operating point is made by using the trimmer on the top of the instrument, protected from the impurity and from accidental tampering with a pressure cap. Turning on the clockwise the operating value increases on the contrary the value decreases. The “XT51P” execution is also available with an extension to intercept fluid into a tank.