Open Loop Or Ground Water Systems - Carrier 50YFV Installation, Operation And Maintenance Instructions

R e s i d e n t i a l D i g i t a l P a c k a g e d U n i t s G T- P B S e r i e s - 6 0 H z P u r o n
Figure 20: Typical Open Loop/Well Application
CAUTION!
CAUTION! Refrigerant pressure activated water regulating
valves should never be used with this equipment.
GT-PB packaged units are available with a water circuit
option for open loop applications (designated by a 6 in the
11th position of the unit model number).
The Motorized Modulating Valve is regulated by the
Communicating DXM2 board based on entering and leaving
water temperature (ΔT). The DXM2 board gives a 0-10v
signal to determine fl ow rate. The motorized modulating
valve defaults to closed position if it loses signal but still
has 24V power running to it. If the motorized modulating
valve loses both signal from the DXM2 board AND 24V
power, it will remain in the same position it was in when it
lost 24V power. DO NOT USE open loop units in closed loop
applications due to signifi cant pressure drop through the
open loop motorized modulating valve. This option is only
available with Cupro-Nickel Water Coil.
To manually open the internal modulating motorized water
valve in YF024 – 036 push down on the handle to unlock
it. Then rotate the handle to the open position as shown
in Figure 19. This fully opens the valve for fl ushing. Once
fl ushing is complete, return the valve handle to its normally
closed position.
To manually open the internal modulating motorized water
valve in YF048 – 060, push down on the lock release button
while turning the handle to the open position as shown in
Figure 19. This fully opens the valve for fl ushing. Once
Open Loop or Ground-Water Applications
Pressure
Tank
Internal Motorized
Water Out
Modulating Valve
Water In
Shut Off
Ball Valves
Boiler
for Isolation
Drains
Optional
Filter
fl ushing is complete, press the lock release again and return
the valve handle to its normally closed position.
Open Loop - Ground Water Systems
Typical open loop piping is shown in Figure 20. 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 coax via the boiler drains without
allowing fl ow into the piping system. Schrader ports built into
unit may be used to measure heat exchanger pressure drop.
Water temperature can be viewed on the communicating
thermostat. Piping materials should be limited to copper, PE,
or PVC SCH80. Note: Due to the pressure and temperature
extremes, PVC SCH40 is not recommended.
Water quantity should be plentiful and of good quality. Consult
Table 5 for water quality requirements. Integrated Variable
Speed Water Flow Control units for open loop applications
always come with Cupro-Nickel coils. 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 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.
Water Quality Standards
Table 5 must 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, 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 5.
Pressure Tank and Pump
Use a closed, bladder-type pressure tank to minimize
mineral formation due to air exposure. The pressure 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 fi 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.
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