AprilAire 720 Humidifier Wiring Instructions

AprilAire 720 Humidifier

The AprilAire 720 Humidifier is designed to improve indoor air quality by adding moisture to the air. This document provides wiring instructions for various configurations and control systems.

Model 60 Standard Wiring

This section details the standard wiring for the AprilAire 720 Humidifier when used with the Model 60 Automatic Humidifier Control. The outdoor temperature sensor should be located on the north, east, or west side of the home, above the expected snow line.

Components:

• AprilAire 720 Humidifier
• Model 60 Automatic Humidifier Control
• Outdoor Temperature Sensor
• Furnace
• 24 VAC 10 VA Transformer (Supplied)

Wiring Connections:

The Model 60 control features an ADHC Terminal Strip with POWER, INPUTS, and OUTPUTS. The humidifier connects to the furnace terminals (R, C, G, Y, W) and the 24 VAC transformer. Yellow wires from the humidifier connect to the transformer.

Diagram Description: A diagram shows the Model 60 control, the AprilAire 720 Humidifier, and their connections to the furnace and a 24 VAC transformer. The outdoor sensor is shown connected to the Model 60.

Model 4655 Wired to HUM Terminal

This configuration shows the AprilAire Model 4655 humidifier wired to the HUM terminal of a thermostat or control system. This setup ensures the humidifier activates only on heat calls.

Requirements:

• HUM terminals must be 24 VAC.
• HUM terminals activate only on heat calls.

Diagram Description: A diagram illustrates the Model 4655 humidifier connected to a control with HUM and C terminals. Yellow wires are shown connecting to the humidifier.

Model 4655 Wired to EAC Using Included Transformer

This wiring method uses the AprilAire Model 4655 humidifier connected to the EAC terminal via a supplied 24 VAC, 10 VA minimum transformer. It's crucial not to wire the transformer into the furnace blower circuit.

Important Notes:

• EAC terminals may be 120 VAC and must be reduced to 24 VAC before connecting to the humidifier or humidistat.
• EAC terminals activate on any fan call.

Diagram Description: The diagram shows the Model 4655 humidifier connected to EAC terminals through a transformer. Yellow wires connect to the humidifier. A note warns against connecting the transformer to the furnace blower circuit.

Model 4655 with Current Sensing Relay

This setup utilizes the AprilAire Model 4655 humidifier with a Model 50 Current Sensing Relay (if required). The relay is connected to the furnace blower motor terminals (Common, HI, LO) and powered by 24 VAC furnace accessory terminals or a transformer.

Notes:

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

Diagram Description: A diagram illustrates the Model 4655 humidifier connected to a Model 50 Current Sensing Relay, which is wired to the furnace blower motor and a 24 VAC source.

Model 4655 with Blower Activation Relay

This wiring configuration uses the AprilAire Model 4655 humidifier with an AprilAire 4851 Blower Activation Relay. The relay activates the furnace blower on a call for humidity.

Notes:

• Model 4851 Blower Activation Relay is sold separately.
• The wire 'G' from the thermostat should be removed from the 'G' terminal on the furnace.

Diagram Description: The diagram shows the Model 4655 humidifier connected to the AprilAire 4851 Relay. The relay is wired to the thermostat terminals and the furnace. Yellow wires connect to the humidifier.

Model 4655 with Air Flow Proving Switch

This wiring diagram shows the AprilAire Model 4655 humidifier connected with an AprilAire 4592 Air Flow Proving Switch. This switch ensures the humidifier operates only when there is sufficient air flow.

Notes:

• Model 4592 Air Flow Proving Switch is sold separately.

Diagram Description: The diagram illustrates the Model 4655 humidifier connected to the AprilAire 4592 Air Flow Proving Switch, which is powered by a 120 VAC source through a supplied transformer.