The paraldehyde chemical heat pump generates cold thermal energy with depolymerization of paraldehyde (2,4,6-trimethyl-trioxane). This study investigates the by-products in the heat pump system. Crotonaldehyde (2-butenal) and the polymer of crotonaldehyde are main by-products. The proposed heat pump system has the solution cycle for the by-product. The cooling rate and the coefficient of performance of the proposed system decreases with a decrease in the amount of cyclic solution.