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Installation
or,
b. vent the coil from the top of the return header down
to the return piping. At the vent connection, size the
return piping to provide sufficient water velocity.
9. Install a "Globe" type valve in the Bypass line as shown
in
Figure 29, p.
47.
Steam Heat Units
Steam heating coils are factory installed inside the heater
section of the unit. The coils are pitched within the units to
provide the proper condensate flow from the coil. To
maintain the designed degree of pitch for the coil, the unit
must be level.
Once the unit is set into place, the steam piping and the
factory provided 2–way modulating valve must be installed.
The valve can be installed inside the heater section or near
the unit. If the valve is installed in a remote location, use
field supplied wiring to extend the control wires from the
heater section to the valve. Two access holes are provided
in the unit base as illustrated in .
Use the following guidelines to enhance both the
installation and operation of the "wet heat" system.
31, p. 48
and
Figure 32, p. 48
piping configurations for the steam coil. lists the coil
connection sizes.
Note: The valve actuators are not waterproof. Failure to
protect the valve from moisture may result in the
loss of heating control.
1. Support all field-installed piping independently from the
heating coil.
2. Use swing joints or flexible connectors adjacent to the
heating coil. (These devices will absorb the strains of
expansion and contraction.)
3. Install the 2-way valve in an upright position. Ensure
that the valve's location lends itself to serviceability.
4. Pitch the supply and return steam piping downward 1"
per 10' of run in the direction of flow.
5. All return lines and fittings must be equal to the
diameter of the "outlet" connection on the steam coil(s).
If the steam trap connection is smaller that the coil
"outlet" diameter, reduce the pipe size between the
strainer and the steam trap connections only.
6. Install a 1/2" 15 degree swing-check vacuum breaker at
the top of the return coil header using the tapped pipe
connection. Position the vacuum breaker as close to
the coil as possible.
Note: Vacuum breakers should have extended lines
from the vent ports to the atmosphere or connect
each vent line to the return pipe on the discharge
side of the steam traps.
7. Install a "Gate" type valve in the supply branch line as
close as possible to the steam main and upstream of
any other device.
8. Install a "Gate" type valve in the return branch line as
46
Figure
illustrates the recommended
close as possible to the condensate return main and
downstream of any other device.
9. Install a strainer as close as possible to the inlet of the
control valve and steam trap(s). Steam trap selection
should be based on the maximum possible condensate
flow and the recommended load factors.
10. Install a Float-and-Thermostatic (FT) type trap to
maintain proper flow. It provides gravity drains and
continuous discharge operation. FT type traps are
required if the system includes either of the following:
a. an atmospheric pressure/gravity condensate return
or
b. a potentially low pressure steam supply.
11. Position the outlet or discharge port of the steam trap at
least 12" below the outlet connection on the coil(s).
This will provide adequate hydrostatic head pressure to
overcome the trap losses and assure complete
condensate removal.
40 to 130 ton units
If two steam coils are stacked together, they must be
piped in a parallel arrangement. The steps listed below
should be used in addition to the previous
32, p. 48
illustrates the recommended piping
configuration for the steam coils.
a. Install a strainer in each return line before the
steam trap.
b. Trap each steam coil separately as described in
Step 10Installation_Steam Heat Units
11Installation_Steam Heat Units
condensate backup in one or both coils.
c. In order to prevent condensate backup in the piping
header supplying both coil sections, a drain must
be installed utilizing a strainer and a steam trap as
illustrated in
Figure 32, p.
Table 21. Connection sizes for hot water and steam
coil
Heat Section
Unit Model and Size
Capacity
SLH_-20 to 130
High or Low Heat
SSH_-20 to 30
High or Low Heat
High Heat Low
SSH_-40 to 75
SSH_-90 to 130
Low Heat(c)
Notes:
1.
Type W coils, with center offset headers, are used in SLH* units; type
NS coils are used in SSH* units
2.
See Digit 9 of the unit model number to determine the heating
capacity.
3.
SSH*—40 to 75 ton units have multiple headers.
steps.Figure
and
Step
to prevent
48.
Coil Connections
(diameter in
inches)
Supply
Return
2½"
2½"
3"
1¼"
3"
1½"
Heat
1½"
1"
RT-SVX072D-EN
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