Detecting fouling of a heat exchanger of a boiler includes emitting a spray of pressurized fluid from a nozzle of a sootblower element when the nozzle is adjacent to a surface of the heat exchanger, and sensing a value indicative of a reactive force created by an impact of the pressurized fluid on the surface of the heat exchanger and translated back to the sootblower element through the spray of the pressurized fluid. The method also includes determining when a substantial deposit is on the surface of the heat exchanger indicating fouling based on the value indicative of the reactive force.