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AIR
FLOW
POSSIBLE
DISPERSION
TUBE
LOCATIONS
AIR FLOW
PROVING
SWITCH
AUTOMATIC
STEAM
HUMIDIFIER
CONTROL
AIR
FLOW
SUPPLY AIR
PLENUM
RETURN
AIR DROP
AIR
FLOW
SUPPLY
AIR DUCT
HIGH LIMIT
HUMIDITY
SWITCH
FIGURE 4 – Split System Installation
90-893
Outside
Air
Filters
Heating Coil
Cooling Coil
Air Flow
Proving Switch
Duct High Limit
Humidity Control
from Dispersion
Point “A”
Motorized
Air Dampers
Dispersion Tube A
Dispersion Tube B
Roof
Economizer
control device
AUTOMATIC
STEAM
HUMIDIFIER
CONTROL
Supply DuctReturn Duct
FIGURE 5 – Rooftop Unit Installation
Above expected
snow line
Outdoor
Temperature
Sensor leads
North, East
or West side
of building
Outdoor
Temperature
Sensor
Sensor
Sensor
Bracket
FIGURE 6 – Outdoor Temperature Sensor Location
90-894
STEP 2: DETERMINE LOCATION FOR CONTROL
AND MOUNT ON DUCT
The Control must be mounted in the return duct of the HVAC system.
See Figure 4 for a split-system installation and Figure 5 for a rooftop unit
installation. The Control must be at least 1 foot upstream of the steam
dispersion tube and any fresh air intake ductwork. Use the template in the
back of this manual to mark the duct opening. After cutting the hole in the
duct, mount the Control tightly to the duct using 4 sheet metal screws
(not provided).
STEP 3: DETERMINE LOCATION FOR OUTDOOR
TEMPERATURE SENSOR
The location of the Outdoor Temperature Sensor must meet these three
requirements:
1. Must be mounted on North, East or West side of building out of
direct sunlight
2. Must be at least 3 feet from all exhaust vents
3. Must be above expected snow line (See Figure 6)
Incorrect humidity levels will result if these requirements are not met.
Attach the sensor bracket to the building with a #8 galvanized screw.
STEP 4: LOCATE ACCESS HOLE FOR WIRING TO
OUTSIDE SENSOR
Look for or provide an opening in the building envelope for running wire to
the Sensor. A convenient way to get wire to the Sensor is to make use of
unused wires running to the A/C condensing unit (if applicable). Other ways
are to use existing holes for telephone lines, A/C lines, water meter, etc.
Read all equipment instructions beforehand for possible conflicts and
warnings. Do not run outdoor temperature sensor wiring alongside
wires carrying high voltage (120VAC or higher).
STEP 5: ALTERNATE LOCATION FOR OUTDOOR
TEMPERATURE SENSOR
The Sensor can also be mounted in the center of either:
• PVC fresh air intake pipe for the split system furnace
OR
• Fresh air intake duct. Mount the sensor with a #8 galvanized screw.
In both cases, the Sensor must be no more than 3 feet from the
outside wall. See Figure 7.
If it is not feasible to use the Outdoor Temperature Sensor in any of the
ways described, the Automatic Steam Humidifier Control can be set for
Manual Operation. See Figure 8 on the next page for details.
90-895