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Closed Loop Ground Source Systems
IMPORTANT: A secondary freeze detection
thermostat is installed in the unit to automatically
start loop circulator pump if the ambient
temperature drops below 20°F. Loop freeze
detection should also be maintained to the lowest
temperature the insulated loop may encounter in
the case of power failure.
NOTE: For closed loop systems with antifreeze protection,
set SW2-1 to the "LOOP" (15°F) position. (Refer to the DIP
Switch Settings table in the Aurora Control section.)
There are several options to attach the earth loop to
the outdoor package unit, bottom connections with a
flow center, side water connections, and bottom valve
connection. The loop should be continued directly under
the unit as shown in the Typical Outdoor Installations
Using Closed Loop. Make the loop to bottom flow center
connection with the supplied Geolink Fusion fittings for
1-1/4" PE pipe (Figure 4A). If the water connections are
on the side of the unit the supply and return water fittings
will be field installed 1" MPT fittings (Figure 4B). If the unit
has the bottom water valve option the connection will be
1" hose. All PE pipe and hose should be insulated with a
minimum of 1/2" closed cell foam from ground level to the
unit connection. When mounting the unit to an existing
concrete slab, holes must be bored through the slab to
accommodate the 1-1/4" PE pipe with insulation. Ensure
proper backfill to support the loop pipe and unit during
settling. The loop pipe can also be installed at the back of
the unit and ran thru the base pan structure to the loop
circulators.
NOTE: Any loop pipe/hosing install outside the unit will
need to be protected or damage may occur.
Once piping is completed between the unit, pumps and
the ground loop, 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. A filter
MUST be used when flushing a loop. The standard 100
micron filter bag (LFC-F100M) is acceptable for capturing
relatively large debris such as pipe shavings, gravel, and
medium sand particles. In certain installation locations
other smaller materials such as fine sand, silt, and clay
can be less than 75 microns. For these smaller particles
the use of the 1 micron filter bag is required (LFC-F1M).
It is also recommended to run the flush cart with the
1 micron filter bag for at least 30 minutes. 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.
AFFINITY SERIES OUTDOOR PACKAGED HEAT PUMP INSTALLATION MANUAL
After pressurization, be sure to turn the venting (burping)
screw in the center of the pump two (2) turns open (water
will drip out), wait until all air is purged from the pump,
then tighten the plug. 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
Pressure Drop table in this catalog. 2.5 to 3 gpm of flow
per ton of cooling capacity is recommended in earth loop
applications.
Figure 4A: Bottom Closed Loop Ground Source
Application
Figure 4B: Side Water Line Connections
NOTE: Additional information can be found in Flow
Center installation manual and Flush Cart manual.
9
Loop Supply
and Return
Piping
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