A hot water heat pump, also known as a heat pump water heater, is an energy-efficient device that extracts heat from the surrounding air and uses it to heat water for domestic or commercial use. It operates on the same principles as an air-source heat pump but is specifically designed for heating water. Here’s how it works:
Heat Absorption: The hot water heat pump is installed in an area where there is access to warm air, such as a basement, garage, or utility room. It can also be installed outdoors in mild climates. It uses a fan to draw in ambient air, which contains heat energy even when it’s cold. This air can be as cold as -5°C (23°F) and still contain usable heat.
Refrigerant Circuit: Inside the heat pump, there is a closed-loop refrigerant circuit. The refrigerant, typically a type of hydrofluorocarbon (HFC), circulates through a compressor, evaporator, and condenser.
Evaporation: The cold air drawn in by the fan passes over the evaporator coil. The heat pump’s refrigerant evaporates in this coil, absorbing heat from the air in the process. As the refrigerant vaporizes, it becomes a low-pressure, low-temperature gas.
Compression: The low-pressure gas is then compressed by the compressor. This process raises the temperature and pressure of the refrigerant, making it significantly hotter.
Condensation: The hot, pressurized refrigerant gas then flows through a condenser coil, where it releases its heat. This heat is transferred to the water in the storage tank or to a separate water circulation system. As the refrigerant loses heat, it condenses back into a liquid.
Heat Transfer: The heat extracted from the air and the heat generated by the compression process are both used to heat the water. The water temperature is raised to the desired level for domestic use.
Heat Distribution: The heated water is stored in a tank, similar to a traditional water heater. It is ready for use, whether for showers, washing dishes, or other hot water needs.
Defrost Cycle: In colder climates, the outdoor air may get too cold for efficient operation. When this happens, the heat pump may enter a defrost cycle, which reverses the refrigerant flow and melts any ice that may have formed on the evaporator coil.
One of the key advantages of a hot water heat pump is its energy efficiency. It can produce 2-3 times more heat energy than the electrical energy it consumes. This efficiency can lead to significant energy cost savings compared to traditional electric or gas water heaters. Additionally, hot water heat pumps can also function as air conditioners in reverse during the summer, providing cooling as well as hot water. It is like having best of both worlds…