A system and method are disclosed for controlling a drywell including a receiver having upper and lower ends with the lower end being more insulated than the upper and having a temperature sensor in thermal contact therewith. Upper and lower heaters are in thermal contact with the upper and lower ends respectively. A controller includes an integrated circuit having a temperature sensor. A reading from the integrated circuit is used to control power to the upper heater and reduce a temperature gradient between the upper and lower ends of the receiver.