a humidistat including an air inlet defining a beginning of an airflow path through the humidistat , a humidity sensor for enabling measurement of the humidity of air flowing along the airflow path , a baffle , a heat source for heating air along a portion of the airflow path , the baffle and the heat source cooperating to define two zones in the humidistat , and an air outlet defining an end of the airflow path . during operation of the humidistat , the air temperature is higher in one zone than in the other zone , and the higher air temperature zone is downstream from the lower air temperature zone in the airflow path .