What characterizes a hydronic heat pump system?

A hydronic heat pump system is characterized by its use of water as a heat transfer medium. This system circulates water throughout the building to either distribute heat in the winter or remove heat in the summer, making it efficient in thermal exchange. The use of water allows for effective heat storage and transfer, as water has a high specific heat capacity which means it can carry more heat than air. This characteristic enables the system to provide steady and even temperature control within the environment.

The other options do not accurately define the features of a hydronic system. For instance, while some systems may use air, hydronic systems specifically rely on water as their heat transfer fluid. Additionally, hydronic heat pumps are capable of operating both in heating and cooling modes, not just in heating mode. Lastly, these systems do not require a separate boiler to function, as they integrate all necessary components for efficient operation.