I n s t a l l a t i o n , O p e r a t i o n , M a i n t e n a n c e
20
W A T E R - S O U R C E H E A T P U M P S
JE-Series
I s s u e D a t e :
M a y 1 0 , 2 0 2 1
Ground-Water Heat Pump Applications
Open Loop - Ground Water Systems -
Typical open loop
piping is shown in Figure 12b. 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 flushing of the
heat exchanger. Shut off valves should be positioned to
allow flow through the coax via the boiler drains without
allowing flow into the piping system. P/T plugs should be
used with units that do not include variable water flow
so that flow can be measured using the pressure drop
of the unit heat exchanger. Units equipped with any of
the four variable water flow configurations have built in
Schrader ports. Water temperature may be viewed on the
intelligent controls communicating service tool.
Supply and
return water piping should be limited to copper, HPDE,
or other acceptable high temperature material. Note that
PVC or CPVC material is not recommended as they are
not compatible with the polyolester oil used in HFC-410A
products.
Water quantity should be plentiful and of good quality.
Consult table 3 for water quality guidelines. The unit can
be ordered with either a copper or cupro-nickel water
heat exchanger. Consult Table 3 for recommendations.
Copper is recommended for closed loop systems and 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
qualified 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 flushing. In some cases, the
desuperheater option should not be recommended due to
hard water conditions and additional maintenance required.
Water Quality Standards -
Table 3 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 indecies 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 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 field, 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 - Units without Variable Water
Flow -
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 off-cycle. Pilot operated slow closing valves are
recommended to reduce water hammer. If water hammer
persists, a mini-expansion tank can be mounted on the
piping to help absorb the excess hammer shock. Ensure
that the total ‘VA’ draw of the valve can be supplied by
the unit transformer. For instance, a slow closing valve
can draw up to 35VA. A typical pilot operated solenoid
valve draws approximately 15VA. Note the special wiring
diagrams for slow closing valves (shown later in this
manual).
WARNING!
Polyolester Oil, commonly known as POE oil, is
a synthetic oil used in many refrigeration systems including
those with HFC-410A refrigerant. POE oil, if it ever comes
in contact with PVC or CPVC piping, may cause failure of
the PVC/CPVC. PVC/CPVC piping should never be used
as supply or return water piping with water source heat
pump products containing HFC-410A as system failures and
property damage may result.
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WARNING!
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