Closed Water-Loop Heat Pump

Closed water loop heat pump systems are some times referred to as the California heat pump system, because conventional wisdom says the concept originated in that state. Today it is widely applied, using reversible water-to-air heat pumps connected to a closed water loop that circulates 60 to 90°F water throughout the building. Use of this un-insulated water loop permits heat to be transferred to where it is needed. Heat is only rejected or added to the building when the internal heat is insufficient to satisfy the load. Another design integrates the sprinkler and loop water piping to reduce cost.

Closed loop systems provide individual room or zone control. They are also flexible to install and lend themselves to thermal energy storage. Installed costs are lower than central chilled water systems but higher than PTHPs.