Comfortable versus too much

Indoor humidity that suits summer can be too high in a cold snap, because windows and exterior walls get much colder.

Signs the setting is reasonable

  • Little or no condensation on windows on cold mornings
  • Less static and fewer dry-skin complaints
  • Hardwood floors without wide winter gaps
  • No musty odor in closets on exterior walls

Signs it is set too high

  • Water running down window glass and pooling on sills
  • Black spots on window caulk or the corners of frames
  • Frost or damp spots on attic sheathing in winter
  • Damp-feeling closets or musty corners on north walls

Why the right number changes with the weather

Warm air holds more moisture than cold air. When indoor air touches a surface colder than its dew point, water condenses. In a deep Colorado cold snap, window glass and the framing at the edge of exterior walls get cold enough that a humidity level that felt fine in November starts producing condensation.

Many humidifier controls include an outdoor sensor or a chart that recommends lower settings as temperatures fall. If yours is a simple manual dial, lowering it during cold spells is a habit worth forming. Large homes with tall windows and two-story great rooms are especially prone, because tall glass collects condensation that runs down onto sills and trim.

Humidifier maintenance that prevents trouble

  • Replace the water panel or pad on the schedule in the manual, usually at least once per heating season.
  • Check the drain line for clogs and confirm water reaches the floor drain or pump.
  • Look for mineral crust or standing water in the unit, a sign it is not draining properly.
  • Close the summer damper or turn the water off at the end of the heating season, if your model has one.
  • Inspect the duct and furnace cabinet around the humidifier for rust or damp spots.
  • Use a separate hygrometer in a living area to check what the control is actually achieving.

What to do with what you find

  • IfOnly window glass fogs on the coldest morningsThenLower the setting during cold snaps and wipe sills dry.
  • IfCaulk and frame corners have black spotsThenLower humidity, clean hard surfaces, and replace badly stained caulk once it is dry.
  • IfAttic sheathing is frosted or stainedThenTurn the humidifier down and have the attic checked for air leaks from the house below.
  • IfThe furnace or duct near the humidifier shows growthThenStop using the humidifier and have an HVAC technician inspect it.

General information for Cherry Hills Village, not a quote or professional advice. In an emergency, call 911.