This study evaluates the feasibility of electricity price-based control for residential heat pumps in the Estonian climate. A control algorithm integrating real-time electricity prices, weather forecasts, and basic building thermal characteristics was tested in a single-family house. The algorithm dynamically adjusts domestic hot water (DHW) setpoints, selectively switches off the heat pump, and applies preheating to shift energy use to lower-cost periods while maintaining thermal comfort. Simulations in IDA ICE and real-world monitoring indicate that this approach can reduce electricity costs by 12% without significantly increasing total energy use or compromising comfort. The results highlight the potential of smart heat pump controls for demand-side flexibility and their role in supporting zero-emission building strategies under the EU Energy Performance of Buildings Directive (EPBD).