A system for coating an interior surface of a heat exchanger includes a tank for storing the coating solution, a pump, a source line for supplying the coating solution to the heat exchanger, and a return line for returning the remainder of the coating solution to the tank. The system can include a pre-treatment line for supplying a pre-treatment solution to the heat exchanger and a water line for supplying water to the heat exchanger. An air compressor can be coupled to the heat exchanger to force the coating solution, the pre-treatment solution, or the water from the heat exchanger.