CLOSED LOOP
(Earth Coupled Ground Loop Applications)
CIRCULATION SYSTEM DESIGN
Equipment room piping design is based on years of experience with earth coupled heat pump systems. The design eliminates most causes of system failure.
Surprisingly, the heat pump itself is rarely the cause. Most problems occur because designers and installers forget that a closed loop earth coupled heat pump system is not like a household plumbing system.
Most household water systems have more than enough water pressure either from the well pump of the municipal water system to overcome the pressure of head loss in 1/2 inch or 3/4 inch household plumbing. A closed loop earth coupled heat pump system, however, is separated from the pressure of the household supply and relies on a small, low wattage pump to circulate the water and antifreeze solution through the earth coupling, heat pump and equipment room components.
The small circulator keeps the operating costs of the system to a minimum. However, the performance of the circulator must be closely matched with the pressure of
head loss of the entire system in order to provide the required flow through the heat pump. Insufficient flow through the heat exchanger is one of the most common causes of system failure. Proper system piping design and circulator selection will eliminate this problem.
Bard supplies a work sheet to simplify head loss calculations and circulator selection. Refer to “Circulating Pump Work sheet” section in manual
COPPER WATER COIL APPLICATION
Copper water coils are available as a factory installed option. The unit model number will indicate the coil option as the next to last character; “C” represents a water coil constructed of copper material and “N” represents a water coil constructed of cupronickel.
The cupronickel coil is suitable for all applications. The copper coil is suitable for applications using ground loop and cooling tower only and is not recommended for open well application.
FIGURE 19
CIRCULATION SYSTEM
FLEXIBLE HOSE
PUMP MODULE (See Spec Sheet for Model No.)
PIPE FROM
GROUND LOOP
PIPE TO
GROUND
LOOP
WATER
OUT
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