9
3.7 - Piping connections
Depending on the application, there are three types of water-
source heat pump 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 water-source heat pump 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 should be
used to isolate the steel parts of the system to avoid galvanic
corrosion.
3.7.1 - 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 elimination equipment comprises a major portion of the
mechanical room plumbing.
The flow rate is usually set between 0.040 and 0.054 l/s per kW
of cooling capacity. For proper maintenance and servicing,
pressure-temperature (P/T) ports are necessary for temperature
and flow verification.
In addition to complying with any applicable codes, consider
the following for system piping:
•
Piping systems using water temperatures below 10
°
C
require 13 mm closed cell insulation on all piping surfaces
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 minimise
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.
3.7.2 - Ground-water applications
Typical ground-water piping is shown in Fig. 8. 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” connector
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.
Fig. 8 - Typical ground-water piping installation
Pressure-
Temperature
Plugs
Boiler
Drains
Strainer – Field-Installed Accessory
(16 to 20 mesh recommended for
filter sediment)
Shut-Off
Valve
Water
Control
Valve
Flow
Regulator
Pressure
Tank
Water Out
Water In
From Pump
Water
control
valve
Flow
regulator
Pressure tank
Water out
Water in
From pump
Shut-off valve
Strainer - field-installed accessory
(16 to 20 mesh recommended for
filter sediment)
Boiler
Drains
Pressure-
temperature
plugs
