Review on Aprilaire 4655 Manual Humidistat by Alexis Guiney

I once replaced a same model humidifier (the last one lasted less than 3 years) while the original Aprilaire humidifier (slightly different) lasted about 8 years. Three years of life is not acceptable. This is a very simple device - when the humidity level is below the set value, the circuit closes; When the humidity exceeds the set value, the circuit opens (which then turns off the humidifier fan). You can test the wiring and electrical connections by: 1) reducing the humidity setpoint to zero, and 2) bridging the two wire connections (it's good if the humidifier turns on when the oven fan is running and not turning on). work without jumpers). Remove the jumper and if the humidity level in the house is dry and the humidity level is set to maximum, the humidistat should work the same way (the stove fan should run again). If not, the touch part is defective.