Before undertaking a cleaning, it’s mandatory you read through your Humidifer’s Owner’s Manual to guide you through specific instructions for maintaining your particular Whole House Humidifier
1.) Make sure that the power is switched off! and that the device is unplugged to avoid any risk of electric shock. Then disassemble the humidifier to access the inside for cleaning.
2.) Empty the water reservoir, and fill it to about 2/3rd level. After this, add a bit of chlorine bleach to take care of any microbes. Swirl the water around so that the solution also cleans the corners of the reservoir. Make sure any scale build-up is removed as well.
3.) Replace your whole house humidifier water panel (water pad/ evaporator pad / filter) annually, or more often if required. (If your instruction manual allows for these to be cleaned with water; immerse them in a tub of cold water and let them lay for about 20 minutes. This will dissolve any dirt and grime.) Drain the water, fill it again, rinse the filter (or wick) and wipe to remove smaller grains of dust. (In many home humidifiers, the wick or water panel is not washable and needs to be replaced on a regular basis.) Once you are done cleaning your filter, replace it with a new one.
4.) Finally, you will want to clean the outer body of your humidifier. For this use a cloth dipped in warm water or diluted vinegar. Be sure to clean your whole house humidifier components contaminated with mineral deposits at the end of the heating season. Clean parts when they are still wet and soft. You can use 50/50 vinegar-water solution for heavier contaminated components. Just soak them for 15-30 minutes (or longer if necessary) for most efficient cleaning.
5.) Make sure that there’s no water dripping from the whole house humidifier itself, and any of its components (water supply line, drain line, shutoff valve, enclosure, area underneath the unit, or furnace itself)
Make sure that you re-assemble everything correctly to prevent water leaks!
Another aspect of maintaining your whole house humidifier is in long-term storage or idle situations. If you’re to be away from your home for a few weeks or more, make sure that you drain the humidifier completely before your trip. Stagnant water in the reservoir can be a breeding ground for bacteria and fungi that could lead to detrimental health issues. When you empty your humidifier, dry it and store it preferably in a dark and dry place.
SOURCE – HVAC.COM