Comfort-Aire HTS Series Split System,Two Stage, 2-5 Tons - Manual (Page 12)

12
Installation, Operation & Maintenance HTS SERIES SPLIT SYSTEM Heat Controller, LLC
Open Loop - Ground Water Systems
(“Indoor” Compressor Section Only)
The “outdoor” version of the compressor section may not
be used with open loop systems due to potential freezing
of water piping. Typical open loop piping is shown in Figure
9. 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 4 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 4.
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.
The pump should be sized to handle the home’s domestic
water load (typically 5-9 gpm [23-41 l/m]) plus the fl ow rate
required for the heat pump. Pump sizing and expansion
tank must be chosen as complimentary items. For example,
an expansion tank that is too small can causing premature
pump failure due to short cycling. Variable speed pumping
applications should be considered for the inherent energy
savings and smaller expansion tank requirements.
Motorized Modulating Water Control Valve
Note the placement of the water control valve in fi gure 9.
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. This valve regulates the fl ow using entering
and leaving water delta-T of the system. Entering and leaving
water temperature is read on the communicating thermostat
or confi guration/diagnostic service tool. Further details on
valve operation are described later in this manual.
Ground-Water Heat Pump Applications -Compressor Section Only