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12
ENVISION SERIES INSTALLATION MANUAL
Closed Loop Ground Source Systems
Note: For closed loop systems with antifreeze protection, set SW2-2 to the “loop” position (see table on page 21).
Once piping is completed between the unit, pumps and the ground loop (see gure below), nal purging and charging
of the loop is required. A ush cart (or a 1.5 HP pump minimum) is needed to achieve adequate ow 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 uctuate with the
seasons. Pressures will be
higher in the winter months
than during the cooling season.
This uctuation 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 ooded. Ensure that the
loop pumps provide adequate
ow through the unit(s) by
checking the pressure drop
across the heat exchanger and
comparing it to the unit capacity
data in the specication cata-
log. Usually 2.5 to 3 GPM of
ow per ton of cooling capacity
is recommended in earth loop
applications.
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 ow center is generally limited to a total of 20 GPM capacity.
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