Efficiency

• Because variable-speed heaters respond to the ambient temperature in the home and are not on when they are not needed, they have a greater efficiency than other, simpler heating mechanisms. This means lower electricity bills.
  
  

Accuracy

• A variable-speed heating system means that the home is kept at optimum temperature. Responding to temperature gains or losses, the heater increases or scales back its function, meaning consistent heating.
  
  

Air Quality

• Variable-speed heaters can be operated at a very slow speed that does not use a lot of energy but continues to circulate air through the home, and allows the air filter in the heater to trap more airborne pollutants. This means that the air quality is better than with other types of heater.
  
  

Humidity

• Ideally, the humidity of a home should be between 30 and 60 percent -- depending on factors such as the outside climate. This helps to prevent the buildup of mold and mildew, which can attack fixtures, fittings and even the structure of the building. The consistent airflow offered by variable-speed heaters helps to keep humidity under control.
  
  

Zoning

• The variable speed of the heater allows greater flexibility in heating the home. It allows you to target areas that are typically cooler -- such as rooms with doors to the exterior -- with more heat than naturally cozier rooms.
  
  

Disadvantages

• The primary disadvantage of a variable-speed heater is that it tends to be more expensive at first than its single- or two-speed relations. The higher specifications required by its mechanical parts lead to a higher purchase price. However, once the initial investment is made, a variable-speed heater should recoup money over time in savings resulting from heating efficiency.