Application
Considerations
Open Loop System
Where an existing or proposed well can provide an ample supply of suitable quality water, ground water systems may be very efficient. (See Figure 7)
Operation and benefits are similar to those for closed loop systems. There are however several considerations that should be addressed prior to installation.
θ An acceptable way to discharge the significant volume of used water from the heat pump should be defined. It may be necessary to install a recharge well to return the water to the aquifer.
θ Water quality must be acceptable, with minimal suspended solids. To help
Figure 7: Open Loop system
ensure clean water, a straining device may be required.
Cooling Tower/Boiler System
A cooling tower/boiler system (see Figure 8) utilizes a closed heat recovery loop along with multiple water source heat pumps in a more conventional manner.
Typically, a boiler is employed to maintain closed loop temperatures above 60 F and a cooling tower to maintain closed loop temperature below 90 F. All the units function independantly, either by adding heat, or removing heat from the closed water loop, making this system more efficient than air cooled systems.
The cooling tower/boiler system provides a low installation cost to the owner than other systems. A good selection for large building design needs.
Figure 8: Cooling tower/boiler system
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