Vertical Tube Integral Face And Bypass (Vifb) And Integral Face And Bypass (Ifb); Shipping Bolts (Vifb Only); Piping Suggestions; Flexible Connectors (Vifb Only) - Pace PAI Installation And Assembly Manual

SECTION 3 - HANDLING, STORAGE, AND INSTALLATION
VERTICAL TUBE INTEGRAL FACE
AND BYPASS (VIFB) AND INTEGRAL
FACE AND BYPASS (IFB)
The VIFB warranty will be voided if the
return piping on the lower header (inlet
and return on two-row header) does not
include flexible connector(s), and if the
lower header(s) bolts are not removed
prior to use.
The VIFB lower header must be free to float as shown
in Figure 160 on page 98. After the coil is piped,
remove the yellow bolts to allow the header to float.
Always back up the coil connections when installing
the fittings.
Below 35.0 °F, the VIFB, as shown in Figure 160 on
page 98, or the IFB, as shown in Figure 161 on page
98, operates with full steam pressure or full water
flow at all times, which prevents freeze-up and tem-
perature stratification.

Shipping Bolts (VIFB Only)

Return steam condensate headers or hot water sup-
ply and return headers are securely bolted to lower
mounting brackets to prevent damage to the header
and tubes during shipment and piping of the coils. Re-
move the bolts before applying steam or hot water, but
after making all of the piping connections, as shown in
Figure 161 on page 98.

Piping Suggestions

Read the following information before installing the
piping.
• Support the steam and hot water field piping sep-
arately after the flexible connector to isolate the
piping strains and additional expansion from the
coils.
• Insulate the internal steam manifolds and piping.
• Size the steam traps three times the calculated
condensate loading at the coil design conditions,
based on the pressure differential across the trap,
not the boiler pressure. Traps should be of types
that pass condensate and air at saturated steam
temperature. Inverted bucket traps should incor-
porate thermostatic air vents.
• Make the return connection full size as required,
and reduce only at the trap. Do not use the reduc-
ing bushing on the coil return connection.
Form PA102.20-N1

Flexible Connectors (VIFB Only)

Return steam condensate headers, hot water supply,
and return headers must be free to float. A flexible con-
nector MUST be installed as close as possible to the
coil, and parallel to the headers to accommodate a
minimum of 1/2 in. expansion movement of the head-
ers.
Failure to install flexible connectors will
restrict expansion of the headers, which
can result in bowing of the tubes, bend-
ing of the fins, interfering with damper
operation, or eventually breaking the
tubes.
Refer to the service manual for more information.

Freezing Conditions

Anti-stratification baffles are standard
on all IFB and VIFB coils mounted in
the AHUs.
The outside air and return air must be thoroughly
mixed before passing over the coil. When freezing air
enters only part of the coil, it creates a greater haz-
ard than when the airflow entering the coil is a uniform
temperature.
Coils used in series with respect to the airflow must
have individual controls with ample space between the
coils for sensing devices, when required. Coils with
two or more rows are more sensitive to freezing than
single row coils.
On outdoor AHUs, locate the low limit at least 24 in.
downstream of the leaving edge of the VIFB/IFB cas-
ing. The low limit element must cross the face and by-
pass areas and be parallel to the headers.
Refer to the IFB/VIFB operator's manual (provided) for
additional piping details. The PACE factory does NOT
pipe the connections to the AHU exterior.
97
Installation & Assembly Manual │ PACE
Issue Date: 07/03/2018
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