Abstract: A thermostat housing assembly includes al seal that seals between the housing and a mounting surface and the between the thermostat and the housing. The housing defines a passage and a flange for mounting the housing to the mounting surface. The seal is attached to the housing within a first annular recess. The seal overlaps a portion of the thermostat disposed within a second annular recess. The portion of the seal that overlaps the thermostat seals the thermostat against the mounting surface. The seal also includes a lead in surface on a radially inward portion. The lead in surface provides for assembly of the thermostat to the housing and holds the thermostat within the housing prior to assembly to the mounting surface.