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Humidifier operates
constantly
• If the humidity level in the building is less than the knob setting or is within the proportional control band (Model 1160 and
1180 only), the Automatic Steam Humidifier Control will operate the humidifier until the humidity level is higher than the
knob setting.
• In the “Test” mode, verify unit will operate for approximately one minute.
• Check the resistance of the sensor by removing the wires of the Outdoor Temperature Sensor and measuring the resistance
across the wires with an ohmmeter. Confirm reading to outdoor temperature in Table 4. (For Manual Operation, verify that
resistance across the leads of Resistor Case is between 44,000 and 48,000 ohms.)
• Make sure the Outdoor Temperature Sensor is mounted completely outside the building on the North, East, or West side of
the building and out of direct sunlight. (Automatic Mode Only).
• Rotate the Automatic Steam Humidifier Control knob counterclockwise to the “Off” position, and observe whether the
humidifier turns off (‘Steam’ indicator light on the humidifier should go off). If the humidifier still operates in the “Off”
position, check summary wiring diagram for correct Automatic Steam Humidifier Control installation.
• If humidifier still does not shut off, refer to the troubleshooting section in the Aprilaire Steam Humidifier Installation,
Operation, and Maintenance Manual.
SYMPTOM
TROUBLESHOOTING PROCEDURE
Humidifier or Automatic
Steam Humidifier Control
“chatters” or clicks ON
and OFF rapidly
• Check voltage at Automatic Steam Humidifier Control “24V” and “C” terminals.
Voltage should be 22 VDC minimum – 26 VDC maximum.
• Make sure Outdoor Temperature Sensor wiring is not run alongside wires carrying high voltage (120 VAC or higher).
(Automatic Only)
Red Diagnostic Light is on
• Check that the wiring is correct. See Figure 9.
• Measure the resistance of the Outdoor Temperature Sensor by removing the leads from the terminal and measuring
the resistance across the wires with an ohmmeter. Confirm the reading with the temperature in Table 4.
(For Manual Operation, verify that the resistance across the leads of the Manual Mode Resistor Case is between
44,000 and 48,000 ohms).
WARNING
Sharp edges on the opening may cause cuts. Use care when cutting the plenum opening and
installing the Automatic Steam Humidifier Control.
CAUTION
• Do not mount Automatic Steam Humidifier Control on supply plenum or duct. The unit will not
withstand supply temperatures and will malfunction!
• When installing Automatic Steam Humidifier Control on counterflow furnaces, ensure blower
continues to run after a heat call is satisfied to eliminate high temperatures from damaging the
Automatic Steam Humidifier Control.
• Do not mount Automatic Steam Humidifier Control downstream of the bypass outlet.
False humidity conditions will cause humidifier to operate incorrectly.
1. CUT TEMPLATE ALONG DASHED LINE.
2. PLACE THIS TEMPLATE ON THE RETURN PLENUM UPSTREAM OF (BEFORE) THE
DISPERSION TUBE.
3. TRACE THE OUTSIDE EDGES OF THIS TEMPLATE.
4. REMOVE TEMPLATE AND ACCURATELY CUT THE PLENUM OPENING.
5. USING 4 SHEET METAL SCREWS, INSTALL AUTOMATIC STEAM HUMIDIFIER CONTROL
IN PLENUM OPENING.
AUTOMATIC STEAM
HUMIDIFIER
CONTROL TEMPLATE
CUT ALONG DASHED LINE