54
CLCH-SVX03C-EN
Coil Piping and Connections
2. Trap each coil separately to prevent holding up condensate in one or more of the coils.
3. Install strainers as close as possible to the inlet side of the trap.
4. If installing coils in series airflow, control each coil bank independently with an automatic
steam-control valve. Size the traps for each coil using the capacity of the first coil in direction
of airflow.
5. Use a modulating valve that has linear flow characteristics to obtain gradual modulation of the
coil steam supply.
Note:
Do not modulate systems with overhead or pressurized returns unless the condensate is
drained by gravity into a receiver, vented to atmosphere, and returned to the condensate
pump.
6. Pitch all supply and return steam piping down 1 inch for every 10 feet in the direction of the
steam or condensate flow.
Note:
Do not drain the steam mains or take-offs through the coils. Drain the mains ahead of the
coils through a steam trap to the return line.
7.
Ensure overhead returns have 1 psig of pressure at the steam trap discharge for every 2 feet
of elevation for continuous condensate removal.
Water Coil Piping
Figure 50
,
Figure 51
, and
Figure 53
illustrate typical water coil piping configurations.
Type WA, 5A, 5W, D, K, W, UW, TT, P,2, P4, and P8 water coils are self-venting only if the water
velocity exceeds 1.5 feet per second (fps) in the coil tubes. Type UU, WD, and 5D water coils are self-
venting only if the water velocity exceeds 2.5 fps in the coil tubes. See the unit submittals for coil
water velocity. If the water velocity is below these minimums, vent the coil by one of the following
methods:
•
Install an air vent in the top pipe plug tapping of the return header.
•
When the return line rises above the top of the coil, vent from the top of the return header
horizontally to the return piping.
Note:
T, ST, and TT coils are designed with larger than normal end tube sheet holes to allow for
maximum expansion. Air leakage around tubes should be expected and handled by
capping over coil ends or by sealing around tubes with a pliable sealant such as silicone.