System information

8
Geothermal Applications
ClimateMaster: Smart. Responsible. Comfortable.
Heat Source/Heat Sink
The heat source/heat sink for geothermal systems is determined
based upon the specifi c application. Where water quality is
good and a suffi cient quantity of water is available, an open
loop (well water) source/sink is a very cost effective solution.
Otherwise, one of the three types of closed loop applications
may be a better choice. In any case, operating costs are
very similar, since the source/sink and heat pump are sized
according to the heat loss/heat gain of the home. All residential
applications (open or closed loop) require extended range
equipment. ClimateMaster residential series equipment is
standard with insulated water and refrigerant circuit insulation,
designed for low temperature operation.
Open Loop Systems (Well Water)
Typical open loop piping is shown in Figure 3. Shut off valves
should be included for ease of servicing. Boiler drains or other
valves should be “tee’d” into the lines to allow acid fl ushing
of the heat exchanger. Shut off valves should be positioned to
allow fl ow through the coaxial heat exchanger via the boiler
drains without allowing fl ow into the piping system. P/T plugs
should be used so that pressure drops and temperatures can be
measured. Piping materials should be limited to copper or PVC
SCH80. Note: Due to the pressure and temperature extremes,
PVC SCH40 is not recommended.
Water quantity must be plentiful and of good quality. Consult
Table 1 for water quality guidelines. The unit can be ordered with
either a copper or cupro-nickel water heat exchanger. Consult
Table 1 for recommendations. Copper is recommended for open
loop ground water systems that are not high in mineral content or
corrosiveness. In conditions anticipating heavy scale formation or
in brackish water, a cupro-nickel heat exchanger is recommended.
In ground water situations where scaling could be heavy or where
biological growth such as iron bacteria will be present, an open
loop system is not recommended. Heat exchanger coils may over
time lose heat exchange capabilities due to build up of mineral
deposits. Heat exchangers must only be serviced by a qualifi ed
technician, as acid and special pumping equipment is required.
Desuperheater (HWG) coils can likewise become scaled and
possibly plugged. In areas with extremely hard water, the
owner should be informed that the heat exchanger may require
occasional acid fl ushing. In some cases, the desuperheater option
should not be recommended due to hard water conditions and
additional maintenance required.
Table 1 should be consulted for water quality requirements. Scaling
potential should be assessed using the pH/Calcium hardness
method. If the pH <7.5 and the calcium hardness is less than 100
ppm, scaling potential is low. If this method yields numbers out of
range of those listed, the Ryznar Stability and Langelier Saturation
indices should be calculated. Use the appropriate scaling surface
temperature for the application, 150°F [66°C] for direct use (well
water/open loop) and DHW (desuperheater); 90°F [32°F] for
indirect use. A monitoring plan should be implemented in these
probable scaling situations. Other water quality issues such as iron
fouling, corrosion prevention and erosion and clogging should be
referenced in Table 1.
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Figure 3: Typical Open Loop Application
Heat Source/Heat Sink