AprilAire 720 Humidifier Wiring Instructions for Various Applications

Model 60 Standard Wiring

This section details the standard wiring for the AprilAire Model 60 Automatic Humidifier Control when connected to an AprilAire 720 Humidifier.

Outdoor Temperature Sensor Placement

The outdoor temperature sensor should be located on the north, east, or west side of the home, positioned above the expected snow line.

Thermostat/Zone Panel Connections

Standard thermostat or zone panel terminals (R, C, G, Y, W) are connected to the corresponding terminals on the furnace.

Humidifier Connections

The AprilAire Healthy Air System Humidifier is connected via yellow wires to a continuously powered 24 VAC, 10 VA transformer.

The Automatic Humidifier Control (Model 60) features an ADHC Terminal Strip with POWER, INPUTS, and OUTPUTS.

The Model 60 control unit displays indoor humidity and allows adjustment based on outdoor temperature.

Model 4655 Wired to HUM Terminal

This configuration shows the AprilAire Model 4655 Humidifier wired directly to the HUM terminal of a control system.

Wiring Requirements

• HUM terminals must be supplied with 24 VAC.
• HUM terminals activate the humidifier only on heat calls.

Connections are made using yellow wires from the humidifier to the HUM and C terminals of the control interface.

The control unit allows setting indoor humidity levels based on outdoor temperature.

Model 4655 Wired to EAC Using Included Transformer

This section describes wiring the AprilAire Model 4655 Humidifier to EAC (Equipment Accessory Control) terminals using a supplied transformer.

Important Notes:

• Transformer Placement: Do not wire the transformer into the furnace blower circuit.
• EAC Terminal Voltage: EAC terminals may operate at 120 VAC and must be reduced to 24 VAC before connecting to the humidifier or humidistat.
• Activation: EAC terminals activate the humidifier on any fan call.

Connections are made via yellow wires from the humidifier to the EAC and C terminals, utilizing a supplied transformer (24 VAC, 10 VA minimum).

Model 4655 with Current Sensing Relay

This wiring diagram illustrates the AprilAire Model 4655 Humidifier connected using a Model 50 Current Sensing Relay, if required.

Connections:

• The Model 50 Current Sensing Relay is connected to 24 VAC furnace accessory terminals or a transformer (10VA minimum).
• The relay's COMMON, HI, and LO terminals are connected to the furnace blower motor.

Important Notes:

• The Model 50 Current Sensing Relay is sold separately.
• Multiple wraps of the COM wire around the relay may be necessary to trigger the Model 50.

Connections are made via yellow wires from the humidifier to the relay.

Model 4655 with Blower Activation Relay

This section covers wiring the AprilAire Model 4655 Humidifier with an AprilAire 4851 Blower Activation Relay.

Wiring Diagram:

• The thermostat wiring (R, C, W, Y, G) is shown, with the wire from "G" to "G" removed.
• The AprilAire 4851 Relay has terminals: BLUE (Normally Closed - NC), ORANGE (Normally Open - NO), YELLOW (Common - C).
• These relay terminals are connected to the humidifier via white/yellow and white/blue wires.
• A constant 24 VAC, 10 VA minimum transformer is used.

Functionality:

• The Model 4851 Blower Activation Relay is sold separately.
• It activates the furnace blower on a call for humidity.

Connections are made via yellow wires from the humidifier to the relay.

Model 4655 with Air Flow Proving Switch

This configuration details wiring the AprilAire Model 4655 Humidifier with an AprilAire 4592 Air Flow Proving Switch.

Connections:

• The AprilAire 4592 Air Flow Proving Switch is connected to 120 VAC and a supplied transformer (24 VAC, 10 VA minimum).
• Connections are made via yellow wires from the humidifier to the switch.

Important Note:

• The Model 4592 Air Flow Proving Switch is sold separately.

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