AprilAire Series 720 Fan-Powered Evaporative Humidifier Installation Guide

Important Safety Information

WARNING/AVERTISSEMENT: Improper installation or maintenance may cause property damage or injury. Disconnect electrical power and water before starting installation or service.

ELECTRIC SHOCK HAZARD: 120 volts may cause serious injury from electric shock.

RISK OF SCALDING: Water temperature over 125°F (52°C) can cause severe burns and scald instantly.

CAUTION/MISE EN GARDE: Sudden operation may cause personal injury or property damage. Turn the humidifier control to OFF or lowest setting before servicing.

CAUTION/MISE EN GARDE: Sharp edges may cause injury from cuts. Gloves and safety glasses recommended.

CAUTION/MISE EN GARDE: Do not cut into refrigerant line.

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

Step 1: Determine Location and Configuration

Select a location on the duct for the humidifier. The unit can be installed on either the supply or return plenum. Supply is recommended for peak performance, as capacity is reduced on the return plenum. Consider accessibility for service and airflow direction.

Configuration Notes:

• Default Configuration: Suitable for most applications.
• Reconfigured: Necessary if nearby obstructions interfere with cover removal/service or if air flows from left to right (horizontal applications). Use the template to determine the best mounting location and configuration.

Important Considerations:

• Ensure 2" of clearance from obstructions to access the handle.
• Do not install on systems with static pressure greater than 0.8" w.c.
• Consider where water, drain, and electrical connections will be made.

Dimensions: The template provides guides for placement, indicating dimensions like 16.5", 6.5", 10.5", and 1.5" for valve clearance.

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)

Tools Needed:

• 1/4" O.D. Copper Tubing
• Low Voltage Wire
• 1/2" I.D. Drain Tubing & Clamp
• Saddle Valve
• Screwdriver (for screws)
• Level
• Marking tool
• Caulk
• Gloves and Safety Glasses (recommended)

Preparation:

• Slide latch to release the cover and rotate it away from the fan.
• Remove the cover and set it aside.
• Tilt the HydroCore forward, remove it, and set it aside.

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

Use the template to determine the optimal location on the duct. Ensure the unit is level. Mark the plenum opening, which should be approximately 14 1/4" W x 14 1/4" H. Cut the opening in the duct.

Important: Do not position the humidifier in front of a blanked-off end of the duct.

Step 4: Mount, Secure, and Seal Unit

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

Note: Remember the two screw holes on the side of the fan module.

Step 5: Insert HydroCore and Replace Cover

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

Step 6: Connect Water Supply and Drain Line

Water Supply: Install a 1/4" O.D. copper water supply line. Purge the water line before connecting to the valve inlet using the included 1-piece compression fitting.

Drain Line: Install a 1/2" I.D. drain hose and secure it with a hose clamp. Route the hose to a floor drain or condensate pump, ensuring a constant downward slope.

Water Conditions:

• Ensure connections are water-tight and adhere to local codes.
• Pressure: 30-120 psi.
• Best Practice: Connect to soft water. Humidifier is effective with hot or cold water. Installations on hard water will require more frequent maintenance. A scale-reducing inline water filter is recommended to lessen the effects of hard water. Hot water is recommended for return-mounted installations.
• Annual maintenance is recommended to prevent mineral buildup.

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

Water Supply Adapter: A push-to-connect adapter may be included for use with code-approved plastic supply lines.

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.

Fan Reconfiguration

This section details how to reconfigure the fan module for left-to-right horizontal airflow systems or improved accessibility in vertical applications. This involves disconnecting and re-routing wires, rotating the base, and reattaching components.

• Disconnect wire leads on the solenoid valve.
• Detach the base from the fan module by activating the lever and sliding the base away.
• Re-route wires to the other side of the fan module and press them into the groove. Ensure wires are fully seated to prevent pinching.
• Rotate the base 180° and slide it back onto the fan module.
• Reconnect wire leads to the valve.
• Remove the "AprilAire" badge by pressing the textured tabs, rotate it 180°, and reattach it to the cover.

Unit Wiring

Refer to control installation instructions for full mounting and setup. The solenoid requires 24 VAC to operate (not a dry contact). Consult furnace manufacturer's guidelines if using accessory terminals.

Wiring Options:

• Model 60 Automatic Digital Humidifier Control (Included with 720A): Connects to thermostat/zone panel, furnace equipment terminals, and a 24 VAC transformer. Yellow wires connect to the solenoid valve.
• Model 4655 Manual Humidifier Control (Included with 720M): Connects to a 24 VAC transformer and the humidifier solenoid. Yellow wires connect to the solenoid valve.
• AprilAire IAQ Thermostat (Not Included): Requires referring to thermostat installation instructions. Connects to a 24 VAC 10 VA MIN. transformer and the humidifier solenoid.

Transformer: A 24 VAC 10 VA minimum transformer is required. The unit requires 24 VAC 10 VA min. to operate (not a dry contact).

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

Fan Speed Switch: The humidifier features a fan speed switch with HIGH (+) for maximum capacity (default) and LOW (-) for quieter operation (approx. 10% capacity reduction). Use the LOW setting for installations requiring reduced sound levels.

Installation and Test Checklist

Verify the following:

• 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). ✔️

Support

For questions, contact AprilAire Technical Support:

Phone: 800.334.6011

Website: aprilaire.com