Dehumidistats are devices typically installed with air conditioning heating and coolingsystems in Florida homes where the home is unoccupied during the summer months. Humidistats are installed for economic reasons to reduce the run time of the air conditioning system and therefore lower utility cost. There is much confusion as to exactly what these devices do and on how to set them. Here, we will take the mystery out of the vacation dehumidistat and provide help in setting the control properly.

Most dehumidistats are wired in series with the power to the thermostat (although some older units are wired in parallel). The device is nothing more than a switch which closes the circuit to the thermostat when the humidity is above the setting on the dial. It is normal to see the display go blank on a digital thermostat when the humidity is below the dial setting. When wired in series, it takes both a humidity level in the home above the dial setting and the temperature in the home above the thermostat setting, before the system will run. The idea is that it can be 90 degrees in the home, but unless there is high humidity, the system does not need to run (and therefore saves electricity). When the home is occupied, the dial should be set to ON to prevent the dehumidistat from interrupting the air conditioning operation.

On units wired in parallel, the dehumidistat acts to override the thermostat. The system will run when the humidity is above the dial setting regardless of the temperature. This method is not as efficient and is no longer widely used.

When leaving for extended periods during the summer months, set your vacation dehumidistat and thermostat as follows:

DEHUMIDISTAT DIAL: 65% (Relative Humidity)



We have found these settings to be best to reduce the chance of mold/mildew growth and still provide adequate utility savings.

To Download A PDF of These Settings Click Here.

If you have any questions about vacation dehumidistats or need to have one installed, please give us a call (954) 772 – 0079.