11
FLOW CENTER INSTALLATION AND LOOP FLUSHING MANUAL
All fl ushing of earth loops should be performed using
a 1.5 hp (1.1 kW) or larger pump. The manufacturer
markets a fl ush cart designed specifi cally for earth loops.
Flushing can be accomplished using three different
methods. The fi rst fl ushing method applies a one-step
installation of the loop, unit, and inside piping. The
second method allows a Loop Contractor to use a fl ush
cart when installing the loop; and, at a later date, the
dealer can install the unit to the loop using only domes-
tic water to fl ush the unit. The third procedure shown is
used when replacing pump, coax or unit. The following
are step-by-step procedures. Be careful not to rotate
the three-way valve into a position where air can be
introduced into the loop. Refl ushing will be needed if this
occurs. Valve position can be verifi ed by looking on the
end of the valve stem for the pattern position. Consult
the Piping Design Manual for more complete fl ushing
and antifreeze instructions. See the following sections for
fl ushing and antifreeze charging specifi cs.
A minimum time of two hours of continuous fl ushing
is recommended to remove all air from the loop. Flush in
one direction only. Do not reverse fl ow.
The presence of air can be detected by “dead head-
ing” the pump. To dead head the pump, close off the
return to the pump and watch the water level in the fl ush tank reservoir. A drop of more than 2 inches indicates that there is
air in the loop.
Power fl ushing can be achieved using the home’s city water supply (or well water) connected to the fl ush cart. This uses
the combined pressure of the fl ush cart pump and the home’s water system for faster fl ushing.
After fl ushing is complete, but prior to unit start-up, remove the large screw from the center of the fl ow center pump to
allow air to escape (water will drip out). Replace the screw after pump has fi lled with fl uid.
For fi nal pressurization, run the unit in heating or cooling for a period of 20 minutes. This time can be used to clean tools
and workspace. After 20 minutes, pressurize the loop using the fl ush cart to 50-75 psi in winter, or 40-50 psi in summer.
In areas where entering loop temperature drop below 40º F (5º C) or where piping will be routed through areas subject
to freezing, antifreeze is needed to prevent the loop water from freezing inside the pipe or heat exchanger. Alcohols and gly-
cols are commonly used as antifreeze; however, you should consult with your representative (or distributor) for assistance
on selecting the antifreeze best suited for your region.
Procedure for adding antifreeze:
a) Flush cart should be 1/2 full of water.
b) Add measured amount of antifreeze through hose below the water level.
c) Add antifreeze to loop side only (see fl ow center valve positions in Figures10a & 10b).
d) Pump and dump (discharge).
e) Turn off pump, close discharge valve.
f) Repeat the procedure to add remaining antifreeze to loop.
Return
Supply
Figure 8: Loop and Unit Flushing
Flushing & Charging
