9
T2GY INSTALLER’S GUIDE
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
Flexible
Duct
Collar
Vibration Absorbing Pad
P/T Plugs
LPK
Drain
Connector Kits with Armaflex
Disconnects
(If Applicable)
GeoLink
Polyethylene w/
Armaflex
TO
LOOP
Auxiliary
Heater
Knockout
Low
Voltage to
Thermostat
Unit Power
Unit Supply
Auxiliary
Heat Supply
* Refer to the
GeoLink Flow
Center installation
manual for complete
information
GeoLink
Flow
Center*
External
Pump
Power
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
Shut
Down
C
C
SL1
In
SL1
Out
GY Unit #1
To Electromechanical Unit
C
S
GY Series to
Electromechanical Units
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
GY Series Unit #1
GY Series or
GY Series Unit #2
GY Series to GY Series
Microprocessor Units
Summary of Contents for T2GY
Page 2: ......
Page 44: ...44 T2GY INSTALLER S GUIDE...
