• Jim

Proper indoor humidity

During the heating season, the average home may have a relative humidity as low as 13%. Amazingly, this is about ½ the relative humidity in the Sahara Desert! What should indoor relative humidity be, then? That depends on outside temperatures, as indicated below:

Outdoor temperature >

Relative humidity

40°C > 45%

30°C > 40%

20°C > 35%

10°C > 30%

0°C > 25%

-10°C > 23%

-20°C > 15%

A humidifier needs a humidistat (counterpart of the thermostat) which can be adjusted as often as necessary to provide the desired level of humidity. The most recent advancement in humidification is a humidistat that automatically delivers the optimum relative humidity without periodic homeowner adjustment. These humidistats adjust the humidity in the home up to 86,000 times per day.

The amount of humidity required in a home is dependent to a certain extent to the way in which the home was constructed. A well insulated house with vapor barriers in the walls, ceilings and slabs, and properly fitting storm doors and windows may need only three (3) gallons of additional moisture per day. A house of similar size but loosely constructed might require five (5) times as much moisture in the same period.

Properly humidified air can help repel problems aggravated by too dry air, such as asthma or allergies. Dry thirsty air evaporates moisture from your skin, a cooling process that makes you feel chilly. However, with humidified levels raised to recommended levels you can dial your thermostat down to 68° and still feel comfortable.

Heated air dries out wood framing around doors and windows, too. Shrinkage of the wood occurs, leaving spaces that permit cold, outside air to infiltrate the home, lowering the inside temperature and requiring more heating. Proper humidity reduces annoying wintertime static electricity shocks.

The damaging effects of heated, parched air can cause separation of wood in floors, trim and furniture, excessive wear of fabrics and carpets, loss of piano tone quality, and cracks in walls or ceilings. It can also cause plants to dry out so they droop and turn brown.

Proper humidification provides the protection that is needed.

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