The invention concerns a thermal compensator unit that allows to precisely set and keep an equilibrium position by providing an adjustable pre-compression on one of two fluid chambers (4, 5). Further, the fluid chambers (4, 5) respectively comprise at least one elastic element (7, 8) so that the respective volume is variable, which elastic elements (7, 8) hermetically seal the fluid chambers, which leads to the effect that no plastic or rubber dynamic sealing is necessary between the sliding parts in a hydraulic compensator, in particular since the moving parts (1) of the hydraulic compensator are preferably hermetically connected to said respective elastic element (7) and/or build a part thereof.