Bard WPV48D, Installation Instructions Manual

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Manual 2100-250
Page 7
CLOSED LOOP
(Earth Coupled Ground Loop Applications)
NOTE: Low temperature thermostat must be reset from factory setting to 15º for closed
loop applications.
This unit is designed to work on earth coupled ground loop systems, however, these systems operate at
entering water (without antifreeze) temperature well below the temperature normally experienced in water well
system.
For information on earth coupled loop design, piping connections to heat pump and installation refer to manual
2100-099, "Earth Coupled Loop System Design Manual," available from your distributor.
THE 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 or the
municipal water system to overcome the pressure or 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 or 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 worksheet to simplify head loss calculations and circulator selection. Refer to "Circulating
Pump Worksheet" section in manual 2100-099.
Two general methods are used to pipe the water circuit in the equipment room. The first and easiest to use is
to install a pump module. This module comes complete with connecting hose and heat pump adapters
available from Bard. A second method is to "site build" the piping at the installation.
To move the transfer fluid (water or antifreeze and water solution) through the earth loop system and the water
source heat pump, some type of circulation system is required. Design of circulation system must include
provisions for the following. See Figure 6.
1. Selection of a circulation pump or pumps for total system.
2. Providing air bleed off before start-up running.
3. Providing for flow monitoring.
4. Positive pressure control and limiting.
5. Antifreeze charging capability.
NOTE: The expansion and contraction of earth loop piping may cause a 50 to 60 psig water pressure charge
in system between summer to winter.