MAINTENANCE INSTRUCTIONS FOR

APRILAIRE HUMIDIFIER MODEL 400

CAUTION! Sudden operation may cause personal injury or property damage. Turn Humidifier Control to “off” or lowest setting before servicing.

1.

Front Cover

 

2. Feed Tube

 

3. Integral Bypass Damper

 

4. Water Panel Evaporator

 

 

Assembly

 

5.

Distribution Tray

 

6.

“V” Notches

 

7. Water Panel

 

8.

Scale Control Insert/Float

 

 

Chamber

 

9. Overflow Hose

 

10.

Float Cover

 

11.

Float

MODEL

12. Water Level Sensor Assembly

400

 

1.Note Humidifier Control setting and turn dial to the “Off” position.

2.Turn off water supply. Turn the integral bypass damper (3) to the SUMMER position.

3.Press the tabs in the latches on the top and bottom of front cover (1) and pull cover off base with both hands.

4.Carefully pull the plastic feed tube (2) out of the distribution tray (5) at the top of the Water Panel evaporator assembly (4). Tip the Water Panel evaporator assembly forward and lift it out of the humidifier. Do not tip the Water Panel evaporator assembly more than needed to clear the housing to avoid over-bending the water level sensor assembly (12).

5.Unsnap the distribution tray (5) from the scale control insert (8). Follow the instructions below depending upon the type of distribution tray in your humidifier:

For trays with a synthetic fabric liner: Lightly scrape out or brush off any mineral deposits, being careful not to stretch or loosen the synthetic fabric liner. Soaking the tray in vinegar or a lime-removing agent is helpful when trying to remove stubborn mineral deposits.

For trays with granular coating: Do not scrape off the granular coating, but lightly scrape out any mineral deposits and clean the “V” notches (6). This textured surface helps ensure even water flow for maximum performance. See page 3 if removed.

6.Slide the used water panel (7) out of the scale control insert/float chamber and dispose of the water panel. Inspect the overflow hose (9) to make sure it is open.

7.Remove the float cover (10) and inspect the floats (11) and float chamber for mineral build- up. Remove deposits as needed from floats, float chamber and scale control insert. Wash the parts with a disinfecting cleaner. Reassemble the floats and float cover. Make sure stems of both floats extend through openings in float cover and that floats move freely up and down.

8.Check the condition of the feed tube and replace if tube is damaged or brittle.

9.Slide a new Aprilaire No. 45 water panel into the scale control insert/float chamber. Snap the distribution tray back on the scale control insert.

10.Re-install the Water Panel evaporator assembly into the humidifier. Take care not to over- bend the water level sensor assembly. Push the top of the Water Panel evaporator assembly firmly back until it snaps into place.

11.Push the end of the feed tube back firmly into the distribution tray. Replace the front cover.

12.Turn on the water supply. Return integral bypass damper to appropriate position.

13.Check system operation:

Humidifier Control: (Automatic or Manual) Check system operation and reset change water panel indicator by setting the knob to “Test/Reset”. With furnace blower operating and furnace calling for heat, humidifier will operate for one minute. DO NOT LEAVE IN TEST MODE AS HUMIDIFIER WILL NOT OPERATE.

14.Reset Humidifier Control to its original position. Check operation.

MODEL 400

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Aprilaire 400 owner manual Model
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400 specifications

The Aprilaire 400 is a high-performance whole-home humidifier designed to enhance indoor air quality and provide superior comfort throughout your living spaces. As part of the Aprilaire family, known for their commitment to creating healthier environments, this model stands out due to its innovative features and advanced technologies.

One of the main characteristics of the Aprilaire 400 is its capacity to humidify homes effectively, covering an area of up to 4,000 square feet. This makes it ideal for large living spaces, ensuring that every room benefits from balanced humidity levels. The humidifier operates seamlessly with the home’s existing heating and cooling systems, requiring no additional maintenance, making it a hassle-free solution for homeowners.

A prominent feature of the Aprilaire 400 is its self-regulating technology. This unit uses a built-in humidistat that senses the moisture levels in your home and adjusts the humidification output accordingly. This ensures optimal humidity—typically between 30% and 50%—which can help reduce issues related to dry air, such as dry skin, irritated sinuses, and static electricity.

Another key benefit of the Aprilaire 400 is its evaporative design, which utilizes a water panel rather than a traditional water tank. This allows for efficient moisture dispersion, as the humidifier draws in dry air, passes it through the water panel, and releases it back into the living space as humidified air. The water panel is replaceable and designed for annual maintenance, promoting long-term functionality and hygiene.

The Aprilaire 400 also incorporates a simple installation process. With compatibility for various heating systems, including forced air and hydronic, it can be integrated into most homes without significant modifications. Its compact design is another advantage, ensuring it can fit unobtrusively in your home, maintaining the aesthetic of your space.

Overall, the Aprilaire 400 whole-home humidifier is a reliable solution for maintaining optimal humidity levels, fostering a healthier living environment, and enhancing overall comfort. With its advanced features, ease of use, and efficient operation, this humidifier is a smart investment for any homeowner aiming to improve indoor air quality and promote well-being.
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