Abstract: A knob adjustment device particularly for adjusting the temperature in valve units for water-heating apparatus. The device comprises a geared transmission interposed between the knob and an operating member of the valve unit in order to transmit a rotary movement to the member about its own axis as a result of a rotation of the knob. The geared transmission includes a reduction mechanism with a variable transmission ratio such that, for a first angular portion and a second angular portion of the rotation of the knob, the member is rotated with respective different transmission ratios (T1,T2).

Abstract: A knob adjustment device, particularly for adjusting the temperature in valve units of a water-heating apparatus. The knob adjustment device is mounted so as to be rotatable about a rotation axis in a stationary housing of the valve unit and has a safety member for the unidirectional restraint of the knob adjustment device relative to the housing so as to oppose rotation of the knob adjustment device in a first direction of rotation about the axis, the knob adjustment device being free to rotate in the opposite direction of rotation.

Abstract: A knob adjustment device particularly for adjusting the temperature in valve units for water-heating apparatus is described and comprises geared movement-transmission means interposed between the knob (2) and an operating member (4) of the valve unit in order to transmit a rotary movement to the member about its own axis as a result of a rotation of the knob. The geared transmission means comprise reduction means (5,6,7,8) with a variable transmission ratio such that, for a first angular portion (C) and a second angular portion (D) of the rotation of the knob, the member is rotated with respective different transmission ratios (T1,T2).

Abstract: A knob adjustment device, particularly for adjusting the temperature in valve units of water-heating apparatus is described. The knob device is mounted so as to be rotatable about a rotation axis in a stationary housing of the valve unit and comprises safety means for the unidirectional restraint of the knob relative to the housing so as to oppose rotation of the knob in a first direction of rotation about the said axis, the knob being free to rotate in the opposite direction of rotation.

Abstract: In the system described for connecting a valve unit for gas water-heaters to a tank of the water-heater, a probe belonging to the valve unit is housed in the tank in a leaktight manner. The system comprises a first element belonging to the valve unit and/or fixed thereto, a second element which projects from the tank and can be housed in a seat of the first element, the second element constituting a support and/or cover for the probe and having an outer surface in which there is a transverse groove, and a third element which is restrained axially on the first element and at least a portion of which extends in the seat in an arrangement such as to engage the groove when the second element is housed in the seat so as to clamp the first and second elements to one another axially, the third element being resiliently deformable between a first position in which the said portion projects into the seat and a second position in which the said portion is outside the seat in order to release the groove.