Water heating represents approximately 18 percent of residential energy consumption annually. Heat pump water heaters (HPWHs) offer an efficient option for residential water heating, because they have the ability to reduce water heating energy consumption by up to 63 percent. To achieve such high efficiencies, HPWHs employ a refrigeration cycle to move heat from the ambient air into water stored in a tank. When HPWHs are in conditioned space, they remove heat from the conditioned air. This study conducted during the winter of 2016 - 2017 provides an objective evaluation of the space conditioning interactions between a HPWH and the heating system in several locations throughout a home to investigate the impact that HPWHs have on space conditioning loads. We have always known there was an interactive effect with home heating systems. This study provides a detailed look at how much and the findings show that there is less interaction effect than we originally thought.