Aprilaire 1870W Dehumidifier Owner’s Manual

Quick guide from the manual

The Aprilaire 1870W is a whole-home dehumidifier designed to control humidity levels by drawing air into the unit, filtering it, and removing moisture through a sealed refrigeration system. This manual provides instructions for setting humidity levels, performing routine maintenance, and understanding diagnostic codes.

Setting the desired humidity level

The unit features an on-board control to manage humidity. Use the UP and DOWN buttons to set the desired relative humidity between 40% and 80%. The unit is factory-recommended to be set at 55% RH upon initial installation.

• More dry: Decrease the humidity setting.
• Less dry: Increase the humidity setting.
• Operation: The unit measures humidity once per hour. It will continue to dehumidify until the level is 3% RH below the set point.

Maintenance

Regular maintenance ensures optimal performance.

Clean or replace the air filter

The air filter should be checked and cleaned every 6 months. A service reminder will appear on the display.

1. Turn the ON/OFF switch to OFF.
2. Remove the filter access door from either side of the unit.
3. Slide the filter out.
4. Flush the filter with warm water and a mild detergent solution.
5. Shake off excess water and allow it to dry.
6. Reinstall the filter, ensuring it is secured in the top and bottom rails.
7. Replace the access door and turn the unit ON.
8. Press the UP and DOWN buttons simultaneously for 3 seconds to clear the service message.

Check the drain

The drain system should be checked annually for blockages or air locks to ensure proper water removal.

Troubleshooting

The on-board control displays diagnostic codes if service is required:

• E1–E7, E9: Contact your installing contractor.
• E8: Indicates incoming air is outside the operating range (below 50°F, above 104°F, or dew point below 40°F). The unit will automatically resume operation once conditions return to the acceptable range.

Caution: Do not use spray solvents or cleaners on or near the inlet side of the dehumidifier. Use a cloth to apply cleaner to the cabinet if necessary.