An additive dispensing device is provided. The additive dispensing device includes a reservoir configured to contain a supply of an additive. The reservoir is in fluid communication with a dispensing chamber of a metering valve device by a first one-way valve. The metering valve device is configured to dispense a portion of the additive from the dispensing chamber into a housing by a second one-way valve. The additive dispensing device further includes a thermal expanding member disposed in the dispensing chamber. The thermal expanding member is configured to expand and contract between expanded and contracted positions, respectively, in response to temperature. The thermal expanding member decreases a pressure in the dispensing chamber as the thermal expanding member moves toward the contracted position, such that additive is drawn from the reservoir into the dispensing chamber through the first one-way valve. The thermal expanding member increases the pressure in the dispensing chamber as the thermal expanding member moves toward the expanded position, such that additive previously drawn from the reservoir chamber into the dispensing chamber is dispensed through the second one-way valve.