This paper presents a base-lag-mean (BLM) method for capturing the temperature rise in a swirl chamber-based inline water heating system. The experimental setup utilizes an internal swirling flow field that promotes the following features: (i) thermal mixing in a rotating flow and (ii) attainment of hot water that maintains its temperature. The base model is based on the global energy balance consistent with a thermal dispersion paradigm. However, the experimental observations lag behind the base model results. This lagging behaviour may be attributed to a lagging input from the heating coil. Accordingly, a lag model is introduced to supplement this lagging input. It is observed that a mean of the base and lag model can produce the temporal progression of the temperature rise consistent with the experimental observations. Accordingly, the BLM method is proposed considering these base, lag, and mean models.