APRILAIRE® AUTOMATIC HUMIDISTAT CONTROL HUMIDIFIER, 18 GALLONS PER DAY THIS HUMIDIFIER FEATURES TRULY AUTOMATIC HUMIDISTAT CONTROL SO THERE’S NEVER A NEED TO MANUALLY CONTROL THE HUMIDIFIER, UTILIZES AN OUTDOOR TEMPERATURE SENSOR FOR MONITORING EVEN THE SLIGHTES CHANGES IN OUTDOOR TEMPERATURE, DELIVERS UP TO 50% MORE MOISTURE IN COMPARISON TO COMPETITIVE UNITS, HAS AN EVAPORATION CAPACITY OF 0.75 GALLONS PER HOURAMONG THE HIGHEST CAPACITY HUMIDIFIERS SOLD, HUMIDIFIES TIGHTLY-CONSTRUCTED HOMES UP TO 4,200 SQUARE FEET IN SIZE. CUL LISTED IN US AND CANADA.