Due to the rising number of networked objects, IoT (Internet of Things)-enabled products are increasingly available on the consumer market, and IoT features are added to conventional home appliances. However, knowledge of the adaptation process of nonexpert users when adopting IoT products at home is still in its early stage. In this paper, we present a four-week qualitative study on how users adapt to an IoT air purifier at home. We aimed to understand the adaptation process an end user goes through when using an IoT product in a domestic environment. Our findings show that users go through four adaptation stages: low expectation, trust building, behavior change, and minimal use. We found that user interfaces that show sensor data affect the transition in the early stages, while actuator-enabled automation influences the transition to the last stage. Based on the understanding of the four stages in adaptation, we suggest design implications to enhance the user experience of accepting IoT products at home in the early and late stages of adaptation.