Applications Manual Bosch Geothermal Heat Pumps
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Bosch Thermotechnology Corp.
Data subject to change
15 Closed-Loop Flushing and
Purging
Once piping is completed between the Bosch geothermal
heat pump, the ow center and the ground heat
exchanger, the loop is ready for nal purging and charging.
A ush cart with at least a 1.5 HP pump is required (and
recommended by IGSHPA) to achieve enough uid velocity
in the ground loop piping system to purge any air and dirt
particles (Fig. 110).
Fig. 110 Flush cart
Courtesy of Geo Flo
An antifreeze solution is used in most areas to prevent
freezing. All air and debris must be removed from the
ground heat exchanger piping before operation. Always
ush the ground loop with a high volume of water at a
minimum velocity of 2 Feet per Second (FPS) in all piping.
The following steps are typically followed for proper
ushing with a ush cart:
1. Fill the ground loop with water from a garden hose
through the ush cart before using the ush cart
pump to insure an even ll (Fig. 111). Connect the
ush cart hoses to the ow center ush ports using
proper adapters. Connect the water supply to the hose
connection on the return line of the ush cart. Turn
both 3-way valves on the ow center to the ush ports
and loop position. Turn on the water supply, making
sure the water is of proper quality.
2. Once full, the ushing process can begin (Fig. 112).
Do not allow the water level in the reservoir to drop
below the pump inlet line to avoid air being pumped
back out to the ground loop. Once the water level
remains above the water outlet in the reservoir leave
the pump running continuously. Catch or lter debris
returning from the loop to the reservoir. Once all
debris is removed turn the 3-way valve to the ush
port/unit position. Make sure the water level is
maintained while lling the Bosch geothermal unit.
Flush the Bosch geothermal unit until all debris is
removed and then return the 3-way valve to the ush
port/loop position.
Fig. 111 Flush cart step 1
Fig. 112 Flush cart step 2
