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
•
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
used, it is located outside the unit and connected directly
to the distributor . Do not apply heat to the body of the
expansion valve .
• The thermostatic expansion valve must be of the external
equalizer tube type . Connect the 1/4" diameter external
equalizer tube provided on the coil to connection on
expansion valve .
•
Use care when piping the system to see that 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 33
)
•
All steam coils in units are pitched toward return
connection .
• 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
• Install vacuum breakers on all application to prevent
retaining condensate in the coil . Generally, the vacuum
breaker is connected 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 .
• Do not drip supply mains through the coil .
•
Do not attempt to lift condensate when using modulating
or on/off control .
M
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www.DaikinApplied.com
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IM 672-11 • VISION AIR HANDLING UNIT
