A rigorous methodology is developed to evaluate the propagation of steady state disturbances through heat exchanger networks. Each exchanger in the network is represented algebraically using the effectiveness-NTU methodology. The properties of the resulting structural disturbance matrices for the network play a vital role in this model. Most industrial processes operate under uncertain operating conditions. These processes require flexible operation and this can be achieved by using an adequate heat exchanger network. The engineer needs to know how well the network will operate under a range of operating conditions. This approach, following on from existing work, gives the engineer a very good insight into the factors which affect the overall responses of a heat exchanger network. However, this new model provides rigorous results over a full and extended range of disturbances and exchanger configurations.