In this paper, we present simplified calculating method for hot water temperature inside the pipe and probability of condensation on surface of cross-linked polyethylene pipe in presumed steady condition, for constructing programs to calculate these elements demanded at situation of marketing or introducing. In addition, we carried out experiment of water temperature and condensation on surface in several condition, to verify preciseness of calculating method by comparing the result of experiment and calculated value. In water temperature inside the pipe, the difference of result of experiment and calculated value was within 0.3 degrees when water temperature is between 40 to 60 degrees. In probability of condensation, relative humidity dew-point value difference of result of experiment and calculated ambient relative humidity dew-point value was within 5.4%. The calculated value was positioned at safe side from experiment value in every case, we concluded this calculation method is practical at marketing situation.