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Closed Loop Ground Source Systems
Once piping is completed between the unit, flow center
and the ground loop, final purging and charging of the
loop is needed. A flush cart (at least a 1.5 HP pump) 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 50-75 psi
(winter) or 40-50 psi (summer). 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
charging the system initially.
After pressurization, be sure to burp the pump. Open
the screw 2 turns only in the end of the pump motor (if
Grundfos® pumps are used) to allow trapped air to be
discharged and to ensure the motor housing has been
flooded. Ensure the loop flow center provides adequate
Closed Loop: Ground Source Application
Unit Supply
Auxiliary
Heat Supply
Disconnects
(If Applicable)
Low
Voltage to
Thermostat
Unit Power
TO
GeoLink
LOOP
Polyethylene w/
Armaflex
Flexible
Duct
Collar
GeoLink
Flow
LPK
Center*
Auxiliary
Heater
Knockout
* Refer to the
GeoLink Flow
Center installation
manual for complete
information
Connector Kits with Armaflex
Drain
P/T Plugs
Vibration Absorbing Pad
AFFINITY COMBINATION INSTALLATION MANUAL
flow through the unit by checking pressure drop across the
heat exchanger (Refer to Pressure Drop table). Usually 2.5-
3 gpm of flow per ton of cooling capacity is recommended
in earth loop applications. Refer to Wiring Schematics for
loop pump power wiring details.
Multiple Units on One Flow Center
When two units are connected to one loop pumping
system, pump control is automatically achieved by
connecting the slave terminals on connector P2 in both
units with 2-wire thermostat wire. These terminals are
polarity dependent (see below). 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.
It is recommended that water solenoid valves be installed
on heat pumps that share a flow center. This is to allow
water flow through only the heat pump that has a demand.
Circulating fluid through a heat exchanger of a system
that is not operating could be detrimental to the long term
reliability of the compressor
Primary/Secondary Hook-up
YACT to YACT
Microprocessor Units
YACT Unit #1
External
SL1
SL1
Shut
C
C
Pump
Down
In
Out
Power
With pump
wired to Unit 1
With pump
wired to
Unit 2
Shut
SL1
SL1
C
C
Down
In
Out
YACT Unit #2
9
YAFT/S or YAFV to
YACT
Series Units
YAFT/S or YAFV Series
YACT to
Unit #1
Electromechanical Units
with AXB Board
SLI
SLO
VS
YACT Unit #1
IN C
OUT
C
Shut
Down
With pump
wired to
With pump
Unit 2
wired to
Unit 1
SL1
SL1
Shut
C
C
Down
In
Out
YACT Unit #1
T o Electromechanical Unit
SL1
SL1
C
C
In
Out
C
S
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Troubleshooting
