Step 7 - Pipe Connections; Water Loop Applications; Ground-Water Applications - Carrier Aquazone 50PTH024 Installation, Start-Up And Service Instructions Manual

Fig. 10 — Condensate Trapping
A vertical air vent is sometimes required to avoid air pockets. The
length of the trap depends on the amount of positive or negative
pressure on the drain pan. A second trap must not be included. The
horizontal unit drain pan is not internally slopped and the unit
should be pitched approximately 1/4 in. towards the drain in both
directions, to facilitate condensate removal.
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 additional 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 tem-
perature 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 condensa-
tion in the case where fluid in loop piping operates at tem-
peratures 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 gal-
vanic corrosion.

WATER LOOP APPLICATIONS

Water loop applications usually include a number of units
plumbed to a common piping system. Maintenance to any of these
units can introduce air into the piping system. Therefore, air elimi-
nation 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 ports are necessary for temperature and flow
verification.
Cooling tower/boiler systems typically utilize a common loop
maintained at 50°F to 100°F. The use of a closed circuit evapora-
tive 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 filtering will
be necessary.
In addition to complying with any applicable codes, consider the
following for system piping:
• Piping systems using water temperatures below 50°F re-
quire 1/2 in. closed cell insulation on all piping surfaces to
eliminate condensation.
• Avoid all plastic to metal threaded fittings due to the po-
tential for leakage. Use a flange fitted substitute.
• Teflon tape thread sealant is recommended to minimize
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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. 11. In addition to
complying with any applicable codes, consider the following for
system 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 pres-
sure and temperature extremes.
1. Teflon is a registered trademark of DuPont.
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