IM 777-8 • Skyline Air Handler 14 www.DaikinApplied.com
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Piping and Coils
When designing and installing piping:
• Follow applicable piping design, sizing, and installation
information in ASHRAE handbooks.
• Observe all local codes and industry standards.
• Do not apply undue stress at the connection to coil
headers; always use a backup pipe wrench.
• Support pipework independently of the coils.
Water Cooling Coils
NOTE:
Use glycol in water coils for outdoor air handlers.
Power failures and other mechanical issues can
expose coils to freezing temperatures.
• Water supply, water return, drain, and vent connections
extend through the end panel of the coil section. All
connections are labeled on the end panel.
• Water supply and water return connections are typically
male NPT iron pipe.
• When installing couplings, do not apply undue stress
to the connection extending through unit panel. Use a
backup pipe wrench to avoid breaking the weld between
coil connection and header.
• Follow recommendations of the control manufacturer
regarding types, sizing, and installation of controls.
Direct Expansion Coils
• The coil distributor and suction connection extend through
the end panel of the coil section.
• Check nozzle in distributor for proper tonnage.
•
When a (field supplied) thermostatic expansion valve
is located outside the unit and connected directly to the
distributor (except on units with piping vestibules). Do not
apply heat to the body of the expansion valve.
• The thermostatic expansion valve must be the external
equalizer tube type. Connect the 1/4-inch diameter
external equalizer tube provided on the coil to the
connection on the expansion valve.
• Use care when piping the system, making sure all joints
are tight and all lines are dry and free of foreign material.
For typical refrigerant piping, see condensing unit product
manual.
Steam Coils
Piping (see
Figure 26
)
• Steam supply and steam return connections typically are
male NPT iron pipe and are labeled on the end panel of
coil section. Connections extend through the coil section
end panel.
• When installing couplings, do not apply undue stress
to the connection extending through unit panel.
Use
a backup pipe wrench to avoid breaking the weld
between coil connection and header .
• Support piping independently of coils and provide
adequate piping flexibility. Stresses resulting from
expansion of closely coupled piping can cause serious
damage.
• Do not reduce pipe size at the coil return connection.
Carry return connection size through the dirt pocket,
making the reduction at the branch leading to the trap.
Coils
• Pitch all steam coils in units toward the return connection.
• Do not drip supply mains through the coil.
• Do not attempt to lift condensate when using modulating
or ON/OFF control.
• Install vacuum breakers on all applications to prevent
retaining condensate in the coil. Generally, connect the
vacuum breaker between the coil inlet and the return
main. The vacuum breaker should be open to the
atmosphere and the trap design should allow venting of
large quantities of air.
