Carnes HXMA Installation Manual

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STEAM MANIFOLD MODEL HXMA

INSTALLATION INSTRUCTIONS

CARNES COMPANY, 448 S. Main St., P. O. Box 930040, Verona, WI 53593-0040 - Phone: [phone]- Fax: [phone] [e-mail] www.carnes.com

FORM 16823

ISSUED: 12-12

LOCATION OF MANIFOLD

The manifold is usually located in the supply duct down­stream of the fan, heating coil, cooling coil, and/or filter.
When installed in packaged units, the manifold is to be
mounted just downstream of the fan discharge where there
is even flow throughout the duct. The unit must be mount­ed the minimum distance calculated in the catalog
upstream of any obstruction to prevent condensation.

The non-wetting dimension is the distance necessary to
prevent condensation on any obstruction downstream from
the manifold that is the same temperature as the air.
Condensation could occur on a cooling coil because of
lower temperatures. Steam plumes may be visible beyond
the non-wetting dimension and may moisten high efficiency
filters. Additional distance is required for installation
upstream of high efficiency filters.

Absorption is also dependent on uniform air flow across the
steam manifold. Uneven flow will result in greater
absorption distances.

Carnes humidifiers operate at .5 psi or less so there are
limitations on the maximum length of hose or piping that
may be used between the humidifier cabinet and the steam
manifold. The maximum distance depends on the static
pressure in the duct and the losses in the piping between
the humidifier and manifold and is shown in Table 1.

Table 1 MAXIMUM STEAM HOSE LENGTH

Duct Static

012345

Pressure “wg

Maximum Steam

40 35 30 25 15 10

Hose Length (Ft.)

In a typical installation, the humidifier is located below the
duct and the steam manifold is installed as shown in Figure
A. In this installation any condensation in the manifold is
returned through a condensate return line to the humidifier
for maximum efficiency. The maximum recommended
length of steam hose for this type of installation is 12 feet.

For lengths beyond 12 feet additional steps shown in
Figure B are recommended so that condensate will drain
from the steam manifold. It is preferable to have the steam
hose rise vertically from the humidifier and then slope
downward to the manifold. Steam flow will assist moving
condensate toward the return line rather than opposing
condensate flow back toward the cylinder if the hose is
running with only a small upward rise. If sufficient head­room is not available, it is possible to install the steam hose
with an upward slope with a minimum rise of 2” for every
12” of run.

Figure A

Figure B

2

The steam manifold may be located below the humidifier if
the installation is made in accordance with Figure C. In this
installation the condensate return line is routed to a drain
below the humidifier and a steam trap is necessary to
prevent live steam from flowing through the condensate line.

The steam manifold cannot be installed in a vertical duct as
shown in Figure D because condensate will not drain
properly and will discharge into the duct.

INSTALLATION OF MANIFOLD

1.

2.

3.

The manifold has an integral mounting flange for ease
of installation. Separate mounting flanges, supplied by
others, are needed for the duct to mate with the
manifold. Refer to Figure E.

Make sure the manifold is oriented properly with the
steam discharge holes facing upward.

Use #12x3/4” self-tapping screws spaced no farther
than 12” to secure the unit to the duct.

Figure D

Figure E

Figure C

INSTALLATION OF STEAM HOSE ANDCONDENSATE
RETURN LINE

It is very important that both the steam hose and conden­sate return line be installed so that sags are prevented.
The steam is at very low pressure and cannot overcome
resistance caused by water standing in the steam hose.
Water accumulating in sags in the return line will restrict
the flow of condensate and may cause water to be dis­charged into the duct.

INSTALL THE STEAM HOSE:
If the steam manifold is used with a humidifier having two

cylinders it will require two separate lengths of steam hose
to connect to the two inlets on the steam manifold. Do not

combine the outputs of two cylinders into one steam
hose. See Figure F.

Figure F

If it is difficult to prevent sags, it is recommended that
copper tube be used as a substitute. If copper tube is
used, a minimum of one inch of insulation must be applied
to prevent excessive condensation and contact with the
hot pipe. A short length of steam hose must be used to
connect the plastic cylinder in the humidifier to the copper
tube and another short length to connect the copper tube
to the steam manifold. Size 3/4” copper tube can be used
with steam cylinders having output rates up to 30 pounds
per hour. Size 1-1/2” copper tube should be used with
steam cylinders over 30 pounds per hour. Length
restrictions shown in Table 1 also apply where copper
tube is used and any 90° elbows add approximately three
feet of equivalent length.

Connect the steam hose to the plastic steam cylinder and
steam manifold using the clamps provided.

INSTALL THE CONDENSATE RETURN LINE:
If it is impossible to maintain a 6” drop from the bottom of

the manifold to the top of the humidifier cabinet the return
line can be run to a separate drain. A trap (usually 8” is
sufficient) may be necessary to prevent loss of steam
through the return line. Do not install a trap if the

condensate is returned to the top of the humidifier
cabinet.

If the humidifier has two cylinders, two return lines will be
required. Connect the return line to the inlet at the top of
the humidifier and to the steam manifold using the clamps
provided.

Two Cylinder

Operation

Steam
Inlets

Return Line
Connections