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GROUND-LOOP APPLICATIONS — Typical ground loop
system is shown in Fig. 4. Temperatures between 25 and
110 F and a cooling capacity of 2.25 to 3 gpm of flow per
ton is recommended. In addition to complying with any
applicable codes, consider the following for system piping:
• Piping materials should be limited to only polyethylene
fusion in the buried sections of the loop.
• Galvanized or steel fittings should not be used at any
time due to corrosion.
• All plastic to metal threaded fittings should be avoided
due to the potential to leak. Use a flange fitted substitute.
• Do not overtighten connections.
• Route piping to avoid service access areas to unit.
• Pressure-temperature (P/T) plugs should be used to mea-
sure flow of pressure drop.
HOT WATER GENERATOR APPLICATIONS (Sizes 036,
060) — The HWG (Hot Water Generator) or desuperheater
option provides considerable operating cost savings by utiliz-
ing excess heat energy from the heat pump to help satisfy
domestic hot water requirements. The HWG is active through-
out the year, providing virtually free hot water when the heat
pump operates in the Cooling mode or hot water at the COP
(coefficient of performance) of the heat pump during operation
in the Heating mode.
All Carrier heat pumps equipped with the HWG option
include a built-in water-to-refrigerant heat exchanger to elimi-
nate the need to open and tie into the heat pump's refrigerant
circuit in the field. The control circuit is also built in. The
concentric fitting is included as a part of the HWG option. An
external pump must be field-provided. Figure 5 is a typical
example of HWG water piping connections.
Using a concentric or coaxial hot water tank connection
fitting eliminates the need to tie into the hot water tank cold
water piping.
Air Pad or
Extruded
polystyrene
insulation board
Concrete
block or
brick
Unit Power
Disconnect
Thermostat
Wiring
Fig. 4 — Typical Ground Loop System (50RWS036-120 Units)
Installation — The HWG aquastat is set at 125 F and is
located on the HWG heat exchanger "Water In" line. If the
HWG is connected incorrectly or if circulation is reversed, the
aquastat will sense leaving water temperature and prevent
HWG operation. UNDER NO CIRCUMSTANCES DISCON-
NECT OR REMOVE THE HWG AQUASTAT. Full load
conditions could drive hot water tank temperatures far above
desirable levels if the aquastat has been disconnected or
removed.
The heat pump, water piping, field-supplied external pump,
and hot water tank should be located where the ambient tem-
perature does not fall below 50 F. Keep water piping lengths at
a minimum. Maximum pipe length is dependent on the exter-
nal pump selected and installed in the field. All installations
must be made in accordance with local codes. The installer is
responsible for knowing the local requirements, and for per-
forming the installation accordingly.
Unit Load Piping
APPLICATIONS WITH WIDE TEMPERATURE VARIA-
TION SUCH AS HEATING/COOLING COILS
• Use piping materials that are rated for the maximum tem-
perature and pressure combination. This excludes PVC
for most heating applications.
• Ensure load water flow in high temperature heating
applications is at least 3 gpm per ton to improve perfor-
mance and reduce nuisance high pressure faults.
• DO NOT employ plastic to metal threaded joints.
• Utilize a pressure tank and air separator vent system to
equalize pressure and remove air.
• Employ an 800-micron particulate strainer in both load
and source plumbing to protect the plate heat exchanger
(size 360).
Load
Flow
Heat
Exchanger
Controller
Connection
Insulated
Hose Kit
P/T Plugs
Stainless Steel
Braided Hose
9
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