Drum humidifier float repair, replace to fix overflow on furnace

Drum or reservoir humidifiers use a rotating drum-styled foam pad or similar media that picks up water for evaporation from a float-controlled reservoir.

These types are the most prone to mold problems, due to the reservoir that is constantly full of standing water. To replace the float: 1. Turn off the furnace power. 2. Turn off the water valve to the humidifier. 3. Remove the humidifier cover. 4. Improve the water level by adjusting the float arm. There is an adjusting screw to alter the level of the float. There may also be a slide to adjust only the level of the float arm itself. 5. Loosen the screw to raise or lower the float to raise the water level. To adjust using the slide you will loosen the nut. 6. Turn on the water valve and power to the furnace. 7. Check the water level again later in the day 8. Make any adjustments to the water level.