Aprilaire 1150 - Manual (Page 19)

Below are field wiring connections:
• Connect to line power.
Refer to the wiring diagram or the dataplate on the outside of the cabinet for wire sizing amperage.
• Connect to control signal wiring.
(from the Automatic Steam Humidifier Control or from signal by others). Mount the Automatic Steam Humidifier Control in the
return air duct as shown in the drawing on pages 14 and 15. See page 21 for wiring details. Also, refer to the Installation and
Operating Manual for the Automatic Steam Humidifier Control.
• Connect to the HVAC system blower.
To start the HVAC equipment blower when the humidifier receives a humidity demand signal, wire the NO, O, and NC control
terminals to the HVAC system as shown on the wiring diagram.
• Connect to a remote fault alarm (optional).
The humidifier may be field programed to send a fault alarm signal to a remote device instead of sending a signal to start the
HVAC system blower. To enable this function, set slide switch S2 position 9 to On and provide wiring to control terminals NO,
O, and NC.
• Connect to the duct airflow proving switch wiring.
The airflow proving switch is a safety device that will prevent the humidifier from producing steam when there is no airflow
present in the HVAC system. See page 23 for details.
• Connect to the duct high humidity limit switch wiring.
(a recommended optional device). Locate the duct high humidity limit switch the correct distance downstream of the
distribution tube. See
Figure 10 on page 14 and Figure 11 on page 15 for more location guidelines.
IMPORTANT: Installation of a duct high humidity limit switch is highly recommended.
CAUTION
Adding alternate conduit connections should not be necessary; however, when making holes and knockouts in the
humidifier cabinet, protect all internal components from debris and vacuum out cabinet when finished. Failure to comply
with this warning can damage sensitive electronic components and void the Aprilaire warranty.
FIELD WIRING
Humidifier field wiring
All wiring must be in accordance with all governing codes and with the humidifier wiring diagram. Wiring diagrams are on pages
9 and 10 in this manual and the wiring diagram for your humidifier model is located inside the removable shroud. Power supply
wiring must be rated for 221°F (105°C). The maximum ambient temperature is 80°F (27°C).
Field wiring connections and requirements
• Conduit knockouts are provided on the top of the cabinet. Control wiring knockouts are on the back right; power wiring
knockouts are on the back left.
• Control wiring and power wiring must be run in dedicated or separate earthed metal conduit, cable trays, or trunking.
• Separate the line voltage wiring from low voltage control circuit wiring when routing electrical wiring inside the
humidifier cabinet.
• Do not use chassis or safety grounds as current-carrying commons. Never use a safety ground as a conductor or neutral to
return circuit current.
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