A stand-alone analytical model using the NTU (number of transfer units) effectiveness approach was developed for a residential desuperheater integrated to a thermal-energy storage (TES) system. This paper describes the basic heat-transfer analysis and presents the characteristics of the model. The output prediction of the desuperheater model was the desuperheater rate. Error analyses of the desuperheater rate indicated that the model predictions were within 12% of the experimental values. A factorial-design sensitivity analysis was conducted to show that the variables Tri and Twi as well as interactions Twi∗hrefrig, hrefrig∗F, Tri∗hrefrig, and hwtr∗hrefrig∗F had significant effects on the desuperheater rate. Although the model involved various assumptions, the results were considered helpful for the design and understanding of the behaviour of the desuperheater.