A thermal control unit for delivering temperature-controlled fluid to one or more patient therapy devices (e.g. pads, blankets, etc.) that are in contact with a patient is disclosed. The thermal control unit includes a fluid circuit with an inlet and outlet, a reservoir, a heat exchanger, a pump, and a controller. The thermal control also includes any one or more of the following: (1) an air eliminator with an air filter for filtering air vented from the fluid circuit to the ambient surroundings; (2) a plug that moves in response to changing fluid levels and that fluidly isolates the air filter from the fluid; (3) a second air filter coupled to the reservoir; (4) a check valve to prevent fluid from back flowing into the reservoir; and/or (5) a liquid filter coupleable to the reservoir to filter liquid entering or exiting the reservoir.