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Fig. 6 — Condensate Trapping
IMPORTANT: Horizontal heat pump drain pan is not inter-
nally slopped.
A vertical air vent is sometimes required to avoid air pock-
ets. 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.
Step 7 — Pipe Connections —
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 con-
nection 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
temperatures 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.
Depending on the
Water
Control
Valve
(field-installed
accessory)
Fig. 7 — Typical Ground-Water Piping Installation
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 ports are necessary for temperature and
flow verification.
Cooling tower/boiler systems typically utilize a common
loop maintained at 50 to 100 F. The use of a closed circuit
evaporative cooling tower with a secondary heat exchange be-
tween 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, consid-
er the following for system piping:
• Piping systems using water temperatures below 50 F
1
require
/
-in. closed cell insulation on all piping sur-
2
faces to eliminate condensation.
• Avoid all plastic to metal threaded fittings due to the
potential 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. 7. 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" con-
nector 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.
Flow
Regulator
(field-installed
Pressure
accessory)
Tank
Shut-Off
Valve (field-installed accessory)
Strainer (field-installed accessory)
(16 to 20 mesh recommended for
filter sediment)
Boiler
Drains
(field-installed)
9
Water Out
Water In
From Pump
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