T H E S M A R T S O L U T I O N F O R E N E R G Y E F F I C I E N C Y
Vertical Stack
R e v. : 0 4 / 2 4 / 2 0 1 9
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c l i m a t e m a s t e r. c o m
Open Loop - Ground Water Systems -
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. 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 quantity should be plentiful and of good quality.
Consult Table 4 for water quality guidelines. The unit can
be ordered with either a copper or cupro-nickel water
heat exchanger. Consult Table 4 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 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 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 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.
Water Control Valve -
Always maintain water pressure in
the heat exchanger by placing the water control valve(s) on
the return 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. This
can overload smaller 40 or 50 VA transformers depending
on the other controls in the circuit. A typical pilot operated
solenoid valve draws approximately 15VA.
Flow Regulation -
Flow regulation can be accomplished
by two methods. One method of fl ow regulation involves
simply adjusting the ball valve or water control valve on the
return line. Measure the pressure drop through the unit heat
exchanger, and determine fl ow rate from. Since the pressure
is constantly varying, two pressure gauges may be needed.
Adjust the valve until the desired fl ow of 1.5 to 2 gpm per
ton [2.0 to 2.6 l/m per kW] is achieved. A second method
of fl ow control requires a fl ow control device mounted on
the outlet of the water control valve. The device is typically
a brass fi tting with an orifi ce of rubber or plastic material
that is designed to allow a specifi ed fl ow rate. On occasion,
fl ow control devices may produce velocity noise that can be
reduced by applying some back pressure from the ball valve
located on the discharge line. Slightly closing the valve will
spread the pressure drop over both devices, lessening the
velocity noise.
Note: When EWT is below 50°F [10°C], 2
gpm per ton (2.6 l/m per kW) is required.
Water Coil Low Temperature Limit Setting -
For all open
loop systems, CXM/DXM JW3 Jumper (LT1) should
never
be
clipped to avoid freeze damage to the unit, and voiding your
warranty. See “Low Water Temperature Cutout Selection” in
this manual for details on the low limit setting.
Ground-Water Heat Pump Applications
NOTICE! Ground-water applications for commercial
buildings with more than 2-3 units should include a
plate frame heat-exchanger to isolate the heat pumps
from the ground-water and confi ne heat exchanger
cleanings to one location and lessen maintenance.
Direct use of ground-water may increase the frequency
of heat pump maintenance and may shorten life
expectancy.
