The size of the project depends on many factors. For one, you have to consider the type of installation, whether it’s an air or water source heat pump. A water heat pump installation involves more work. Another factor is the size and design of your home. Larger homes with complex designs will involve more work. Lastly is the existence of ductwork. A fresh installation involves a lot of work. But if it’s only a heat pump replacement with pre-existing ductwork or a ductless unit, then it’s less time-consuming.