With this installation, inputs such as hot and chilled buffer tank temperatures, 22 room thermostats and outside air temperature are all taken into account to control geothermal heat pumps, circulating pumps and a plethora of control valves.
When the heating and cooling loads are similar, the heat pump(s) will maintain the hot and chilled buffer tanks. This essentially means that heat is moved from one location, to another within the same building. For example, domestic hot water can be heated with the heat extracted from a space requiring cooling.
When the loads are unbalanced (more heating or cooling required), a valve with direct flow to the geothermal field and start the field circulating pump(s). In this mode, heat can be extracted from or rejected to the field at a system COP (coefficient of performance) in the order of 4.
In this case, the geothermal field included a series of vertical boreholes to 300′.