8
STEAM DISTRIBUTOR PIPE LOCATION
(Continued)
Steam distributor pipes must be located on a plumb surface so
condensate that forms will run back into the return line. The pipe
should be located in the center of the duct to insure distribution
of steam into the airstream. A minimum clearance of 4” must be
maintained between the top of the duct and the distributor pipe.
The steam distributor pipes are usually located in the supply duct
downstream of the fan. When installed in packaged units the
distributor should be mounted just downstream of the fan
discharge.
It is important to locate the distributor pipe as far upstream as
possible from any obstructions in the ductwork so that moisture
can be absored before it contacts a surface and accumulates.
There must be a
minimum
of six feet between the distributor and
any fans, coils, filters, dampers, elbows, or outlets downstream to
reduce the possibility of condensation.
It may be possible to minimize the absorption distance by using
multiple distributor pipes, or for extremely short absorption
distances, a manifold may be required (See Short Absorption
Manifold Section in this manual). Duct air temperatures below
60°F may require a condensate drain pan below the steam
distributor pipe. Always avoid locating the distribution pipe
upstream from any insulation in the duct as excess moisture may
cause damage.
The distributor pipe may be located below the humidifier if the
installation is made in accordance with
Figure H
. A trap may
be necessary to prevent steam from flowing back through the
condensate return line.
In a vertical duct with either upward or downward air flow the
distributor pipe should be installed horizontally as shown in
Figure F
.
Figure F
Steam
2”
12”
.5”
12”
Figure E
Steam
Figure C
Optional if
sufficient
head room
is not
available.
When hose is difficult to support
within this length, straight
copper tube should be used
and insulation applied.
Steam line
must pitch
down toward
drain tee —
NO
pockets,
sags or
horizontal
runs.
Mounting
plate must
be plumb.
Condensate hoses
must pitch down
continuously to
humidifier —
NO
pockets,
sags or horizontal runs.
Drain Tee
To Drain
HOSE LOCATION
FOR RUNS FROM
12 FEET TO 40 FEET
Trap, if
condensate
routes to drain.
Figure H
Mounting
plate must
be plumb.
Condensate hoses
must pitch down
continuously to humidi-
fier or common drain —
NO
pockets, sags or
horizontal runs.
Drain Tee
HOSE LOCATION
WHEN DUCT IS LOWER
THAN HUMIDIFIER
Water trap required
to prevent live steam
from returning.
Trap to
common
drain.
If multiple pipes are used they should be staggered as shown in
Figure G
.
Figure G
Air Flow
Figure D
Common Drain
Trap
Condensate
Extended Length
