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VERTICAL UNITS (50PSV, PSD) — Each unit uses a con-
densate hose inside all cabinets as a trapping loop, therefore an
external trap is not necessary. See Fig. 12.
Each unit must be installed with its own individual vent and
means to flush or blow out the condensate drain line. Do not in-
stall units with a common trap or vent.
VENTING — Install a vent in the condensate line of any
application that may allow dirt or air to collect in the line. Con-
sider the following:
• Always install a vent where an application requires a long
horizontal run.
• Always install a vent where large units are working against
higher external static pressure and to allow proper drainage
for multiple units connected to the same condensate main.
• Be sure to support the line where anticipated sagging from
the condensate or when “double trapping” may occur.
• If condensate pump is present on unit, be sure drain connec-
tions have a check valve to prevent back flow of condensate
into other units.
Step 7 — Pipe Connections — Depending on the
application, there are 3 types of WSHP piping systems to
choose from: water loop, ground-water and ground loop. Refer
to Piping Section of Carrier System Design Manual for addi-
tional information.
All WSHP units use low temperature soldered female pipe
thread fittings for water connections to prevent annealing and
out-of-round leak problems which are typically associated with
high temperature brazed connections. Refer to Table 1 for
connection sizes. When making piping connections, consider
the following:
• Use a backup wrench when making screw connections to
unit to prevent internal damage to piping.
• Insulation may be required on piping to avoid condensation
in the case where fluid in loop piping operates at tempera-
tures below dew point of adjacent air.
• Piping systems that contain steel pipes or fittings may be
subject to galvanic corrosion. Dielectric fittings may be
used to isolate the steel parts of the system to avoid galvanic
corrosion.
WATER LOOP APPLICATIONS — Water loop applications
usually include a number of units plumbed to a common pip-
ing system. Maintenance to any of these units can introduce air
into the piping system. Therefore, air elimination equipment
comprises a major portion of the mechanical room plumbing.
The flow rate is usually set between 2.25 and 3.5 gpm per
ton of cooling capacity. For proper maintenance and servicing,
pressure-temperature (P/T) ports are necessary for temperature
and flow verification.
Cooling tower/boiler systems typically utilize a common
loop maintained at 60 to 95 F. The use of a closed circuit evap-
orative cooling tower with a secondary heat exchange between
the tower and the water loop is recommended. If an open type
cooling tower is used continuously, chemical treatment and fil-
tering will be necessary.
In addition to complying with any applicable codes, consid-
er the following for system piping:
• Piping systems using water temperatures below 50 F
require
1
/
2
-in. closed cell insulation on all piping surfaces to
eliminate condensation.
• Avoid all plastic to metal threaded fittings due to the poten-
tial to leak. Use a flange fitted substitute.
• Teflon tape thread sealant is recommended to minimize
internal fouling of the heat exchanger.
• Use backup wrench. Do not overtighten connections.
• Route piping to avoid service access areas to unit.
• Flush the piping system prior to operation to remove dirt
and foreign materials from the system.
GROUND-WATER APPLICATIONS — Typical ground-
water piping is shown in Fig. 13. In addition to complying
with any applicable codes, consider the following for sys-
tem piping:
• Install shut-off valves for servicing.
• Install pressure-temperature plugs to measure flow and
temperature.
• Connect boiler drains and other valves using a “T” connec-
tor to allow acid flushing for the heat exchanger.
• Do not overtighten connections.
• Route piping to avoid service access areas to unit.
• Use PVC SCH80 or copper piping material.
NOTE: PVC SCH40 should not be used due to system high
pressure and temperature extremes.
Water Supply and Quantity
— Check water supply. Water
supply should be plentiful and of good quality. See Table 2 for
water quality guidelines.
IMPORTANT: Failure to comply with the above required
water quality and quantity limitations and the closed-
system application design requirements may cause damage
to the tube-in-tube heat exchanger. This damage is not the
responsibility of the manufacturer.
Alternate
Condensate
Location
Vent
1/4” per foot
slope to drain
3/4” Copper FPT/PVC
Water
Connections
1/2”
1/2”
3/4” PVC
NOTE: Unit does not need to be sloped toward drain.
Fig. 12 — Vertical Condensate Connection
A50-6262
NOTE: Trap should be deep enough to offset maximum unit static
difference. A 4-in. trap is recommended.
Fig. 11 — Trap Condensate Drain Connection
A50-7732