Instructions to change a wick air filter on an Essick humidifier might vary between different models. The following instructions apply for an Essick Air Products HD1407 humidifier, and they may need to be adjusted slightly based on the model of humidifier being worked on.
Before taking apart the humidifier, first unplug the unit. Lift off the top cover or chassis of the Unit, and remove the left and right water bottles from the unit. The wick filters are found in filter housings that sit in the base of the humidifier. The filter housings can be removed by simply lifting them out. The two filter housings hold two filters each, and they are interchangeable.
To change the filters, unsnap the front of the filter housing, and remove the top and bottom supports. The old filters come out easily and can be discarded. Slide the new filters into the filter housings, and press it into place, making sure the side of the filter with the blue stripe is facing inside and the fan side is facing out.
Once all four filters are put into place, put the top back onto the filter housing, starting at the back and pushing the wicks down as the front is being lowered. The filter housings may then be placed back into the humidifier, making certain the side labeled front is in the front. Then, reassemble the rest by placing the cover back on and refilling and replacing the water bottles.