If you have a whole-house humidifier, it’s very important to clean interior parts of a humidifier according to the manufacturer’s schedule and instructions. Keeping pans, panels, filters, and floats free of mineral scale helps the system run efficiently. In addition, heavy buildups of mineral scale provide a haven for the growth of microorganisms, including bacteria, mildew and mold, which have been linked to respiratory distress and allergic reactions in sensitive individuals.
If you don’t have a whole-house humidifier:
An excessively dry indoor climate happens frequently in homes that aren’t sufficiently sealed against cold air infiltration. The atmosphere loses half of its ability to hold water vapor for each 18°F / 10°C decrease in temperature. In typical winter conditions, that can mean infiltrating air is four times drier, or more, than the humidity a comfortably heated home can support. That reduces relative humidity inside the house, and many people solve the problem by using a humidifier.
Unless you live in an extremely dry climate, you may be able to reduce, or even eliminate, the use of a humidifier. Sealing a home by installing or replacing caulk and weatherstripping -- and taking other measures to block air infiltration in the basement and attic -- will help your home retain more humidity in winter. A tighter house also means lower heating and cooling bills.
Either contractors or do-it-yourselfers may perform house-sealing tasks. Materials needed for this work are inexpensive, and will pay for themselves in one year or less if homeowners install them properly.
Tenants may not be able to go as far as homeowners, but a few simple measures can help. Use inexpensive plastic window-sealing kits and removable rope caulk to block cold drafts through frames and small gaps. Most reasonable landlords won’t mind at all if you replace worn-out door and window weatherstripping. This minor maintenance is probably needed if it hasn’t been done in the past 10-15 years, and it will pay you back quickly in lower heating bills and greater comfort.