Fouling of heat transfer equipment is a complex industrial problem. Many experiments have been carried out on a small scale to study the problem, but few models which can be used industrially have been developed. One problem may be that multiple mechanisms, often found in fouling, make scaleup very difficult. A series of possible scaleup strategies are tested using a computational model of a simple heat exchanger, and it is shown that, without a very good understanding of the basic mechanisms of fouling, scaleup may be very difficult in practice.