AprilAire Series 720 Fan-Powered Evaporative Humidifier

Fan Left Installation

This guide provides instructions for installing the AprilAire Series 720 Fan-Powered Evaporative Humidifier. Please read all instructions carefully before beginning.

Important Safety Information:

• Disconnect electrical power and water before starting installation or service.
• 120 volts can cause serious injury or death from electric shock.
• Water temperatures over 125°F (52°C) can cause severe burns.
• Sharp edges may cause injury. Wear gloves and safety glasses.
• Sudden operation may cause personal injury or property damage. Turn the humidifier control to OFF or the lowest setting before servicing.

Step 1: Determine Location and Configuration

Default Configuration: The unit is designed for a standard installation. Ensure adequate clearance for service and cover removal.

Reconfiguration: Reconfigure if nearby obstructions interfere with cover removal/service, or if airflow is from left to right (horizontal applications). Use both sides of the template to determine the best mounting location and configuration.

The humidifier can be installed on either the supply or return plenum. Supply is recommended for peak performance. Capacity is reduced on the return plenum. Consider humidifier dimensions and accessibility.

Note: Do not install on systems with static pressure greater than 0.8" w.c.

Step 2: Verify Contents and Prepare Unit for Installation

What's in the box:

• Model 720 Humidifier
• Humidifier Control
• Model L HydroCore™
• Installation Template
• 24 VAC 10 VA Transformer
• Saddle Valve
• Installation Kit (720AKZ, 720MKZ only)
• Copper Tubing
• Low Voltage Drain Tubing & Clamp

Tools Needed:

• Screwdriver
• Pliers
• Wire Strippers
• Drill
• Pipe Cutter
• Measuring Tape
• Level
• Caulk

Step 3: Determine Location on Duct, Then Level, Mark, and Cut

Plenum Opening: 14 1/4"W x 14 1/4"H. Use the template to mark the opening.

Important: Consider water, drain, and electrical connections. Softened water is recommended to reduce annual maintenance.

Caution: Do not cut into refrigerant lines.

Step 4: Mount, Secure, and Seal Unit

1. Angle the top of the base toward the duct opening and engage hooks.
2. Hinge the humidifier toward the opening and slide down to engage bottom hooks.
3. Secure the unit with eight (8) #8-3/4" flanged hex head screws.
4. Seal the edges with caulk to prevent air leaks.

Step 5: Insert HydroCore and Replace Cover

1. Ensure the rubber seal cap is in place on the valve orifice. Align the HydroCore to the valve, tilt, and snap it in place.
2. Align the cover to the outside edge of the base and push or pivot into place. Ensure the cover is fully latched to avoid air leaks.

Step 6: Connect Water Supply and Drain Line

• Install a 1/4" O.D. copper water supply line. Purge the water line before connecting to the valve inlet using the included compression fitting.
• Install a 1/2" I.D. drain hose and secure with a hose clamp. Route to a floor drain or condensate pump, ensuring a constant downward slope.

Water Conditions:

• Pressure: 30-120 psi
• Best Practice: Connect to soft water. Installations on hard water will require more frequent maintenance. A scale-reducing inline water filter is recommended.
• Hot water is recommended for return-mounted installations.

Notice: Install a condensate pan with a float switch or other active leak prevention device when installing in or over a finished space.

Drain Line: Use a clear, flexible drain tube. If using hard pipe, a minimum of 6" of flexible tube is required between the humidifier and the pipe for drain cleaning access.

Step 7: Connect Electrical Wiring

• The solenoid valve requires a 24 VAC transformer with at least 10VA to operate.
• Plug the supplied power cord into a 120 VAC outlet. Do not alter or hardwire the power cord.

Unit Wiring:

Refer to the included control installation instructions for full mounting and setup. The solenoid requires 24 VAC to operate (not a dry contact).

Model 60 Automatic Digital Humidifier Control (Included with 720A):

• Connect the 24 VAC transformer to the ADHC terminal strip (POWER).
• Connect the humidifier solenoid wires to the appropriate terminals (e.g., Yellow wires to EAC and HUM).
• Connect the thermostat or zone panel to the appropriate terminals.
• Connect the outdoor temperature sensor if applicable.

Model 4655 Manual Humidifier Control (Included with 720M):

• Connect the 24 VAC transformer to the control.
• Connect the humidifier solenoid wires to the control.

AprilAire IAQ Thermostat (Not Included):

• Follow thermostat-specific wiring and setup directions. Typically involves connecting 24 VAC power, the humidifier solenoid wires, and potentially an outdoor temperature sensor.

Reminder: Plug the power cord (located on the fan module) into a 120 VAC outlet.

Fan Reconfiguration

Note: Applicable for left to right horizontal airflow systems and improved accessibility in vertical applications. Turn template over and see step 1 for details.

Steps for Reconfiguration:

1. Disconnect wire leads on the solenoid valve.
2. Detach the base from the fan module by activating the lever and sliding the base away.
3. Re-route wires to the other side of the fan module and press into the groove. Ensure wires are not pinched.
4. Rotate the base 180° and slide back onto the fan module.
5. Reconnect wire leads to the valve.
6. Remove the badge by pressing the textured tabs, rotate 180°, and reattach to the cover.

Humidifier Fan Speed Switch:

HIGH (+): Maximum capacity (default).

LOW (-): Quietest operation (approx. 10% capacity reduction). For installations requiring reduced sound levels, adjust the switch from high to low.

Installation and Test Checklist:

• All plumbing connections are watertight.
• Humidifier is plugged into a 120 VAC outlet.
• Solenoid valve is connected to 24 VAC.
• Humidifier functions properly: Fan turns on, solenoid valve opens, water flows down the drain (approx. 5 mins).

For questions, contact AprilAire Technical Support at 800.334.6011 or visit aprilaire.com.