12
NSZ/NDZ INSTALLATION MANUAL
NOTE:
For closed loop systems with antifreeze protection, set
SW2-2 to the “loop” position (see DIP Switch Settings table).
Once piping is completed between the unit, pumps and the
ground loop (see figure below), final purging and charging
of the loop is required. A flush cart (or a 1.5 HP pump
minimum) is needed to achieve adequate flow velocity
in the loop to purge air and dirt particles from the loop
itself. Antifreeze solution is used in most areas to prevent
freezing. Flush the system adequately to remove as much
air as possible then pressurize the loop to a static pressure
of 40-50 PSI (summer) or 50-75 PSI (winter). This is
normally adequate for good system operation. Loop static
pressure will fluctuate with the seasons. Pressures will be
higher in the winter months
than during the cooling season.
This fluctuation is normal and
should be considered when
initially charging the system.
After pressurization, be sure
to remove the plug in the end
of the loop pump motor(s) (if
applicable) to allow trapped air
to be discharged and to ensure
that the motor housing has been
flooded. Ensure that the loop
pumps provide adequate flow
through the unit(s) by checking
the pressure drop across the
heat exchanger and comparing
it to the unit capacity data
in the specification catalog.
Usually 2.5 to 3 GPM of flow
per ton of cooling capacity is
recommended in earth loop
applications.
Figure 7: Typical Split System Application Closed Loop - Earth Coupled
Disconnect
Thermostat Wire
From Air Handler
Vibration Absorbing Pad or Air Pad
P/T Plugs
Lineset
To Air
Handler
Insulated
Flow Center
Electrical Supply
GeoLink
Flow Center
To Loop
DHW Out
Rubber Hose Connector
Kit CK4L or CK4S
DHW In
Envision to
Electromechanical Units
Shut
Down
C C
SL1
In
SL1
Out
Envision Unit #1
To Electromechanical Unit
C
S
Shut
Down
C C
Shut
Down
C C
SL1
In
SL1
Out
SL1
In
SL1
Out
Single Speed
Envision Unit #1
With pump
wired to Unit 1
With pump
wired to
Unit 2
Envision to Envision
Microprocessor Units
Envision Unit #2
Single Speed
With pump
wired to Unit 1
With pump
wired to
Unit 2
Shut
Down
C C
Shut
Down
C C
SL1
In
SL1
Out
SL1
In
SL1
Out
Dual Capacity
Envision Unit #1
Envision Unit #2
Dual Capacity
Envision to Envision
Microprocessor Units
Figure 8: Primary/Secondary Hook-up
Closed Loop - Ground Source Systems
Multiple Units on One Flow Center
When two units are connected to one loop pumping
system, pump control is automatically achieved by
connecting the SL terminals on connector P2 in both units
with 2-wire thermostat wire. These terminals are polarity
dependant (see Figure 8). The loop pump(s) may be
powered from either unit, whichever is more convenient. If
either unit calls, the loop pump(s) will automatically start.
The use of two units on one flow center is generally limited
to a total of 20 GPM capacity.
