Coil Piping and Connections
CLCH-SVX009A-EN
31
Steam Coil Piping
Air handlers fitted with steam coils have labeled holes for
piping penetrations.
Figure 29
illustrates a typical steam
coil piping configuration. See
Table 8
for the codes of
system components in these figures.
The coil condensate return line must be piped full size of
the condensate trap connection, except for a short nipple
screwed directly into the coil header’s condensate return
tapping. Do not bush or reduce the coil return trapping
size.
Figure 28.
Drain pan trapping for negative and positive pressure applications
H
J
L
Drain pan trapping for section
under negative pressure
L = H + J + pipe diameter where:
H = 1 inch for each inch of negative
pressure plus 1 inch
J = 1/2 H
Drain pan trapping for section
under positive pressure
L = H + J + pipe diameter where:
H = 1/2 inch (minimum)
J = 1/2 inch plus the unit positive static
pressure at coil discharge
(loaded filters)
Table 8.
Code of system components for piping figures
Code
System component
FT
Float and thermostatic steam trap
GV
Gate valve
OV
Automatic two-position (ON-OFF) control valve
VB
Vacuum breaker
ST
Strainer
AV
Automatic or manual air vent
MV
Modulating control valve
Figure 29.
Typical piping for Type NS steam coils and
horizontal tubes for horizontal airflow
Full size of
coil connection
ST
GV
MV
Steam main
Pitch down
VB
GV
Airflow
12 in. min.
FT
ST
12 in. min.
Full
size
of
main
VB
GV
ST
FT
Return main
Full size of
steam trap
connection
ST
FT
