Open Loop-Ground Water Systems - Heat Controller HTV Series Installation, Operation & Maintenance Instructions Manual

GROUND-WATER HEAT PUMP APPLICATIONS

OPEN LOOP-GROUND WATER SYSTEMS

Typical open loop piping is shown in Figure
7. Shut o valves should be included for
ease of servicing. Boiler drains or other
valves should be "tee'd" into the lines to
allow acid ushing of the heat exchanger.
Shut o valves should be positioned to allow
ow through the coax via the boiler drains
without allowing ow into the piping system.
P/T plugs should be used so that pressure
drop and temperature 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 should be plentiful and of good
quality. Consult Table 3 for water quality
guidelines. The unit has a cupro-nickel
water heat exchanger. Consult Table 3 for
recommendations. 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 quali ed technician,
as acid and special pumping equipment is
required. Desuperheater 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 ushing.
Additional maintenance may be required.
WATER QUALITY STANDARDS
Table 3 should be consulted for water quality
requirements. Scaling potential should be
assessed using the pH/Calcium hardness
method.
HTV/HTD/HTH SERIES
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 indecies should be
calculated. Use the appropriate scaling
surface temperature for the application,
150°F for direct use (well water/open loop)
and HWG; 90°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 3.
EXPANSION TANK AND PUMP
Use a closed, bladder-type expansion tank
to minimize mineral formation due to air
exposure. The expansion tank should be
sized to provide at least one minute
continuous run time of the pump using its
drawdown capacity rating to prevent pump
short cycling. Discharge water from the
unit is not contaminated in any manner and
can be disposed of in various ways,
depending on local building codes (e.g.
recharge well, storm sewer, drain eld,
adjacent stream or pond, etc.). Most local
codes forbid the use of sanitary sewer for
disposal. Consult your local building and
zoning department to assure compliance in
your area.
WATER CONTROL VALVE
Note the placement of the water control
valve in Figure 7. Always maintain water
pressure in the heat exchanger by placing
the water control valve(s) on the discharge
line to prevent mineral precipitation during
the o -cycle. Pilot operated slow closing
valves are recommended to reduce water
hammer.
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