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4. Install a "Gate" type valve in the supply branch line as
close as possible to the hot water main and upstream of
any other device or takeoff.
5. Install a "Gate" type valve in the return branch line as
close as possible to the return main and down stream of
any other device.
6. Install a strainer in the hot water supply branch as shown
in Figure 3-12.
7. Install the 3-way valve in an upright position, piped for
valve seating against the flow. Ensure that the valve's lo-
cation lends itself to serviceability.
8. The Type "W" hot water coil used in SLHF units is self-
venting only when the tube water velocity exceeds 1.5
feet per second (fps). If the tube velocity is less than 1.5
feet per second, either:
a. install an automatic air vent at the top of the return
header, using the tapped pipe connection;
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 3-12.
Table 3-5
Connection Sizes for Hot Water & Steam Coil
(See Note 1)
Heat
Section
Unit Model
Capacity
and Size
(Note 2)
SLH*-20
High or
to 130
Low Heat
SSHF-20
High or
to 30
Low Heat
SSHF-40
High Heat
to 75
(Note 3)
Low Heat
SSHG-90
Low Heat
to 130
(Note 3)
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 130 Ton units have multiple headers.
Steam Heat Units (SSH_)
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 main-
tain 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 two way modulating valve must be in-
stalled. The valve can be installed inside the heater section
or near the unit. If the valve is installed in a remote location,
Coil Connections
(diameter in inches)
Supply
Return
2-1/2"
2-1/2"
3"
1-1/4"
3"
1-1/2"
1-1/2"
1"
Installation (Continued)
use field supplied wiring to extend the control wires from
the heater section to the valve. Two access holes are pro-
vided in the unit base as illustrated in Figure 3-2.
Following the guidelines listed below will enhance both the
installation and operation of the "wet heat" system.
Figure 3-13 illustrates the recommended piping configura-
tions for the steam coil. Table 3-5 list 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 ex-
pansion 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" di-
ameter, 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
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).
10. Steam trap selection should be based on the maximum
possible condensate flow and the recommended load
factors.
11. Install a Float-and-Thermostatic (FT) type trap to main-
tain proper flow. They provide gravity drains and continu-
ous discharge operation. FT type traps are required if the
system includes either;
a. an atmospheric pressure/gravity condensate return;
b. a potentially low pressure steam supply.
35
or,
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